Have Trunk Soft Close / Trunk Assist problems. Here is how to fix DIY.
 

A common problem on many of our cars is the the trunk assist will randomly stop working one day, and you won't know why. You can unhook the convenience battery and reconnect, and the soft close function will begin to work again, but not for long. Eventually it will stop pulling the trunk closed again, and you will have to pull the fuse (or unhook the battery). This is only a temporary fix which could ultimately result in pump failure.

The problem with our cars is that the soft close latch is operated by air, and if there is a leak anywhere in the system, the pump times out, and the soft close function ceases to work until the system is reset.
So, on the latch mechanism, there are 4 air ports that mercedes plugged with small ball bearings. These bb plugs work fine when the latch mechanism is new, but as the plastic around them ages, it cracks where these ball bearings are. The cracks allow air to escape, and here is the problem.
The solution is to buy some $5.00 plastic epoxy, and glue the outside of the ports and the inside of the ports shut.
You will notice some orange silicone on the latch assembly. I initially tried to use silicone gasket maker to cover the ports, but quickly found out it was not strong enough :smash:, and the air pushed its way out. So make sure you use a strong plastic epoxy. Gorilla Glue makes a great gel (super glue) epoxy. I used it later...

In the next series of photos i will show you how to resolve the problem permanently.

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After you pull the latch mechanism out reset your convenience battery, push the latch clasp in 1 click, watch as the pump actuates and closes the clasp fully, and LISTEN FOR AIR ESCAPING.. When you find the air leak, begin applying the glue there, but also apply it to the other ports just in case. Be generous..

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You could take your car to the dealer and pay over $300+ to have a new latch installed, or you could fix it like i did in less than 30min and for less than $5.00

Wow...excellent write up. And the timing of this post couldn't be better as this is happening to me now. I did try disconnecting and reconnecting the battery and that worked...but only for a little while and I wasn't sure why it worked (I didn't know about the pump timing out).

Is there one pump that does all the pnuematics in the car? Is there anything else that I would see not working after this pump times out...or just the trunk assist?

I ask because eveything else in the car seems to work fine...though I confess that I don't know everyplace where this pnuematic system is used. And I'm concerned about this because I just did an audio upgrade and I had alot of things apart and perhaps I inadvertantly cut into an air line some place. I'm not thrilled with the idea of looking for that...so I'm hoping the fact that other things are working might tell me the problem is in the latch area this post describes and not someplace else.

Thanks for this thorough post!

There is only 1 pump that runs the pnuematics for the car. When the trunk mech has cracks and leaks air, the pump runs to long, the car senses a leak, and then trips an E-Fuse that wont allow solenoids on the trunk mech to open and close (recieving air). They instead remain closed which seals the pnuematic circuit, but won't allow it to reopen until it is reset (hince the trunk assist won't work until the system is reset, and then it will only work for a short time). Every other pnuematic function in the car will still work (seats, locks, etc.). The pump iteslf is not shut off, just the trunk mech.
I doubt you cut a line, because then the pump would continuously run and burn itself out in no time, and you wouldn't have the other pnuematic functions working.

This is why the trunk assist stops working. It is electronically separated from the pnuematic system in order to save the pump.

^Hope all this makes sense... Looks like you need to go buy some plastic epoxy and take about 30min-an hour out of your day to glue your trunk mechanism... Its an easy fix...

Nick

It does make sense...and it makes me feel better knowing that I probably didn't cut a line somewhere because everything else (seats, locks, storage latches, etc) still works fine.

But unfortunately, I don't think the epoxy fix will do it in my case. Didn't mention this is my first reply, but the other night...when I discovered this and I was 'experimenting' with how hard I had to slam the trunk to get it to fully close without the assist...I heard that dreaded, distinctive sound of something plastic breaking and moving about / falling through the interior cavity of the latch area. So yeah, I may be replacing that entire latch assembly after all. But thankfully I have your write up and pictures to get me to the point where I can pull the latch assembly and see how broken it really is. But I will have some Gorilla Glue on hand in case I get lucky!

Of course, on the other hand, my car is still under warranty. And even though something in there broke seemingly because *I* slammed the trunk, I wonder if the dealer will fix it for me? Or will he say its my fault for slamming it? Or will he see my audio upgrade and automatically tell me it must be my fault. Hmmm...I may still take a look at it before calling the dealer.

Thanks again!

A very prompt and world class response to my first post. Many thanks to Rick SL55 and NikleinR6. Can't wait to try this and report back!

And as a follow up to my last post, I brought the car to the dealer and they covered it under warranty.

Funny enough, my service advisor spent more time asking me about what components I used in my audio upgrade than he did about discussing what was going on with the trunk closing issue! :)

NikleinR6/Nick, I think you're one of my favorite posters/contributors. I am not having this issue, but appreciate your post and taking the time to write this up. Bravo!

I also absolutely love your SL.

Plus 1! What he said! This is a great tutorial and as a new member of this forum it tells me a lot about the quality of the forum and the wisdom and experience of it's members and their willingness to share. Thanks! :y

Dumb question...do all of our cars have soft close trunks? Mine doesn't seem to.

Thank you so much for the kind words....

-Nick

I am nearly positive all R230's have it, but i could be wrong.
Do this, try unhooking your rear trunk battery for about 20 seconds (remove the ground/NEG cable). Then reconnect the ground cable and softly close the trunk lid. If it pulls shut you know that
A. Your car has the soft close
and
B. You have a leak in your latch that has caused the pump to time-out in the past, and therefore trip the latch's E-fuse (which stops the latch mech. from enabling soft-close or close assist)..

Hope this helps..
Nick

If there is still warranty on the car would this be covered?

Mine was covered under the original factory warranty (on my 2007 SL550).

I did the 4 ports and it still didn't work but with looking more into it there were 6 ball bearings you kinda have to disassemble it a little bit to glue them correctly but all is good now with all 6 sealed up.
Justin

Also make sure you get a gel epoxy made just for plastic and something that is easy to work with some of the spots are tight and close to other fittings you can not get glue on.

I'm about to dig into my latch, but has anyone had any long term issues after repair? Just wondering why the bb's in the 1st place. Seems like they are designed to inhale and I'm curious if there were any side effects from sealing them.
Thanks Nik for the detailed write-up. I never would have attempted it on my own.

The bbs are there to seal the ports. When the latch is new they work quite well but as the latch housing plastic ages, the housing around the bbs cracks and leaks. The ports do not inhale. The pump will just pump air not suck it. When you glue the mechanism, you are essentially sealing cracks that have formed from use, age, and stress. Good luck with the fix. It's a piece of cake. It's been months and the mechanism still works perfectly, and I haven't reset the battery once.

Nick

Had to do this twice so far, lets see if it works this time. Located and covered the 4 holes that didnt work then with further inspection i found a total of 6 holes to glue, now its back together drying hope this works or it time for a new unit.
Justin

This should be stickied. It will help a lot of peole.

From Soft Close to Tele Aid
 

OK, finished repairing my soft close this morning - had to let the glue set overnight. Everything appears to be working as designed. THANKS NikleinR6 for your instructions! They were exact.
However when I started the car after completing the repair I got a tele aid malfunction - drive to workshop, and SOS in the left display. I don't subscribe and don't have a phone in my car. Anyone else have this issue or know how to erase the malfunction? I presume it's telling me I don't have tele aid, but I've never seen the malfunction before this. Everything else (Nav, GPS, CD) is working. Thanks.

Glad to see it worked out.

Sometimes when you remove and reconnect the rear battery the car will do funny things. One time I lost sound from the radio and it wouldn't recognize the cd changer.. all I did was remove the ground cable, wait a bit, and reconnect again. If this doesn't solve the issue let us know. There may be other steps you can take.

Mine after sealing all 6 holes is working perfect still. Thanks again for the diy!
Justin

Thanks NikleinR6 - I only removed the fuse to the pump, I didn't disconn the battery. I'll remove the ground - how long is a bit?

Also, I saw your post to repair the vario flaps, but I noticed that my "closed" sensor was a bit flat so I bent it out a little. I'm crossing my fingers, but it's tight. It used to fall every time the trunk lid was lowered and adjusting the screws was no help. Lowered the roof several times today - no issues.

Rob

Tele Aid Malfunction
 

Disconnecting the ground (1/2 hour) did not reset the tele aid malfunction. Any other suggestions?
From googling, seems like this is a very common problem with all mb models, but most either live with it or take it to the dealer. Just can't figure out if it's related to my soft close fix or a coincidence.
Thanks.

Other two ports
 

For those of you who are looking for the other two ports that need to be sealed. Here is a picture of them. They are very hard to get to but using a bent peice of wire to apply the glue it is possible.

Thanks for the tips, Nick. Looks like the latch is almost identical on a W215 CL.

Just a note for everyone else, if it trips the breaker when you close the trunk, the problem is one of those ball bearings or a leaking hose. If it trips the breaker when you open the trunk, it's the bladder/actuator (small hockey puck looking thing attached to the latch). This piece is inflated and then the bladder actuates the unlocking mechanism (this is the worst engineering imaginable).

You need to remove the puck (it is secured with two round prongs, which you push back through). Then take it apart to see how it works. You need to epoxy this back together around the "hemisphere." Use some JB Weld, caulk it up, put it back together, and then clamp it together until it dries. That should hold it.

A related item I found: If the latch works fine, but the red auto close button doesn't work (assuming you have this feature) and/or when you unlock the trunk it just sits there (instead of popping up), then your hydraulic pump is leaking.

The latch uses pneumatics (air from the PSE pump) to lock, unlock, and "soft close" (meaning to suck a door or trunk that is almost closed until it is fully closed).

However, there is a separate hydraulic (oil) pump used by the auto close feature, which engages when you press the red button in your trunk. The pump is located either under the battery (on a W215) or by the battery (in a W220 and I think also in the SL models), behind the passenger side trunk shielding. Remove the plastic shielding, locate pump, remove. The transparent plastic container is a reservoir, and it's probably empty. Remove and refill with oil (ATF or power steering should work). Now use the system and you'll find the leak. Either it's slow, meaning you just need to refill it, or it's gushing (probably from one of the fittings on the piston the hoses attach to. I used QuikSteel to "caulk" the fitting to stop the leak. Refill the reservoir again, and your auto-close should now be working.

Hey ,
 

this is a great post. I know it hasn't been touched in a while....but I overloaded my trunk this weekend, and pretty sure that I need to replace/reset the fuse for the soft close. I have the panel off and can see them all, but cannot identify which one--I know it's a 20 amp one, but which one? This isn't a car you just randomly want to replace fuses in! Thanks for your help.

Thanks Nick!! Great to see a DIY actually working. I followed all the steps and my trunk now has a fully functional soft close! World of difference and saves me a lot of frustration (previously the car would frequently tell me to close the trunk if I wanted to let the roof down).

Four things I learned in the process:

1) you really need to spend some time to find a good plastic epoxy glue in order for this to work. I misread the description and bought Gorilla Super Glue but that did not work. The Plastic Epoxy I bought next did the job.

2) In my case, it was sufficient to only apply the epoxy to the inside (to cover the leaking ball bearing). The outside was not cracked and could do without glue to keep it clean.

3) it is WAY easier to fill the ball bearing ports with glue if you detach the whole air compartment. Instead of using bent pieces of wire to reach the hard-to-reach ports, you can simply disconnecting the green, yellow and black air tubes and then press the two clip-hooks inwards to take out the whole compartment. It is small and gives you easy access to all properly glue all 6 ports.

4) when I re-installed everything I made an error and had the black air tube block the latch release. The effect was that the trunk would soft-close but immediately after open again. Pushing back the black air tube and strapping solved this.

My soft close just stopped working last week. working the open lever did open the trunk. Came across this thread. Reset the consumer battery and the soft close started to work again.

So I have my latch pulled out. I am listening for all I am worth, but I can't hear any air leaks. I hesitate to start gluing this dude up if I can't hear a leak. However, it does appear that there are cracks on the top of at least one port, and all of the ports are showing stress in the form of the plastic being lighter grey right around the bbs.

For those of you that have gone before me, a few questions.

How many uses of the soft close would you get before the e-fuse would trip? I have cycled it a dozen or so times in my hand listening for the air leaks and it is still working...

What brand of glue did ya use?

What is the trick to disconnect the air delivery hose?

And most importantly, how loud were the leaks? I am tempted to get my leak detector fluid or some windex but that is a messy process....

Thanks!

Slider

Well, I never heard an air leak. But I took it all the way out and glued it up anyways. I could see what appeared to be stress cracks and stretching so since it was in my hand....

Put it back together. Trunk seems to operate fine.

Fired up the car, and the ESP is not available. Also, when I climb in the car and shut the door, the window doesn't go back up an inch like normal.

Uh oh...

So now I have pulled the consumer battery off and will leave it off for a few and see what happens.

Anyone have any other thoughts, please post!

resetting the consumer battery didn't fix the door window issue...

There are a few things that need to be reset after disconnecting the battery. Windows, seats and something to do with turning the wheel from all the way right to left - might be esp. Check your owner's manual - it should detail it. I know for the windows you have to put them down, then up (all 4) and continue to hold the switch in the up position for 2 sec. MB calls it synchronizing. The seat as I recall is all the way up then all the way back.

I did what you did and for me it resulted in a TeleAid malfunction - and $100 labor at MB to reset. MB recommends NEVER disconnecting the consumer battery. To change it you need a charger attached. Fun cars but way overengineered.

Good luck!

Read your post and it got me thinking.

So I shut the trunk, which pulled itself shut nicely. Then I cycled the roof down and up. That fixed the windows.

Drove it about 500 feet, and the traction control re-activated.

Trip the MB only cost me 5 bucks for 2 clips!!!

I am still not totally convinced that my problem was a leak in this mechanism, but in 6 months, if it is still running, I guess we will know. There were cracks there, but nothing obvious, and even with careful listening, I couldn't hear any air leaking out. But, all things considered, fairly easy repair. Really not too hard to pull the component with the bbs in it all the way out, I would recommend doing that to folks reading this.

Great thread, it covers pretty much everything you need to know! There are two push-clips holding the carpet in place on the trunk lid that you will have to find and pop thru before you can get your hands up in there, and the trunk latch is a little ball and socket deal that pops apart with a twist at the top. (kinda like my shoulder...) I found twisting the socket that is on a threaded rod to be the easiest way to dislocate the connection. Then you can push the latch mechanism up thru the cutout in the lid and take it out.

When you start testing the unit make darn skippy sure you know where your fingers are before popping the trunk latch to the soft close position. Don't want to think about the damage you could do if the mechanism closed on your finger....

Other than that little bit of pay attention or it will hurt a lot, this was a really easy repair. I went slow and spent about an hour and a half. But I only lost 1 clip and finished with no extra parts.

Thanks for the great instructions!!!!

Slider

This was a GREAT DIY savings :rolf:

I replaced the latch, it was far gone and the plastic peice to hold the bar to open was cracked. Now when I close it the pump runs for about ten seconds. after 2 of 3 cycles it stops working. Any ideas?

I'm going to try the superglue fix in September, when I have a few days off from work to screw it up and try to fix it again. In the meantime your "disconnect the battery" trick worked in a time when I needed it most (9:00 pm with expected rain overnight and top stuck down!). If you ever come to Philadelphia I'd like to buy you a beer!

OK, finished on Thursday, let sit till Saturday all is well in MB world.

Trying for the life of me to figure out why after spending $125,000.00 that all they use is BS plastic. not ABS but Bull S--t plastic. LOL


for the allenjdmb Post. the fuse set for this feature is in the storage box behind the passenger seat, hard to see, but the bottom comes up with the two tabs on the floor of the box to the rear, pull it up and you will see fuses facing forward, the third from the left is the 20 amp #71 thats your puppy you are looking for.

thanks to all for the fix on this problem, I saved a small fortune and I did not call GEICO. LOL

Zookeeper

I reset the roof and everything else and now the soft close seems to work fine after a week.

Careful....
 

On my 65, the third fuse was blank....it was the fourth. Better make extra sure. Might be different in the ROW. The fuse fix worked for a while for me, but ultimately quit, had to do the reseal fix suggested here....

Trunk issue
 

Hi Nick,

Just got a 2003, S500. Wehn I press the soft close botton, it kind of comes down a bit Fast (have to move out of the way) initially and then slow . It sits on the base but does not shut tight. Is this the same issue as you had?? WOuld I be able to try this on my ride as well or would it have a different type of mechanism?? Please help.

Very cool post guys. I will be trying this one soon...Thanks

Hi guys I recently overloaded my trunk this weekend and the soft close suddenly stopped, can you guys tell me if this is a normal issue? and do i have to do the DIY steps to fix it or is there a way to reset it. thanks guys

Epoxy
 

Epoxy glue implies resin/hardener type glue?
I am not sure how you actually epoxy glue the ball bearings or the vacuum hoses.
Do you remove the hoses & fill them up with epoxy glue?

Absolutely DO NOT epoxy any hoses or connectors where hoses go. Please read the DIY again, or don't attempt this fix....

Where can I buy used control unit for SL500 03 model..
Part number: 032 545 04 32
The unit is found under the steering wheel

Great Fix, but I get "close trunk lid" dash message
 

Fix worked great, and now my 04 SL55 soft close works fine and trunk is closed tight. But before the fix, I could slam the lid hard and then lower the top. After the fix, I have the red light on at the remote trunk release switch and the "close trunk lid" message on the dash if I try to open the top. I can't get the computer to recognize that the trunk is closed tight. I've reset the codes by disconnecting batteries and jumping cables.

What sets off those warnings? If there is a sensor, where is it and how do you work around or replace it?

epoxy problem?
 

I am having the toughest luck fixing the stupid trunk.
i did all that you told me to do, except i used JB WELD.
Will this cause the following problem?

------ After covering all holes, I disconnected then reconnected the Aux Battery in the trunk next to the spare tire.

------ The soft close will work for 2 - 3 times, then stops working and i have to slap shut the trunk.

If using JB WELD vs. Gorilla glue is the problem, does anyone know how to remove JB WELD?? (lol)

Thank you!

Great write up! In the 9 years that I have owned my SL55, this is one of the few 'challenges' that I have had with the car.

I'm glad I decided to post a 600tt sale today. Otherwise I may not have seen this. Well done!

This is a terrific post. I followed it, using a top quality plastic epoxy. Unfortunately the fix last only a couple of weeks. Then I did it again, but the fix lasted only a few closes. So I had to break down and buy a replacement closer for $265 from Ft Lauderdale MB online. Before the final fix, the necessary slamming of the trunk lid on the occasions when the closer broke down caused my third brake light to break out of the deck lid. Fortunately, I had that great plastic expoxy, which easily repaired the broken light, and allowed me to reinstall it (hand tight only, or it'll break.) All is fine now.

Guys, thanks for this great Post. I have a 2005 SL600 w 20k miles.... Soft close stopped functioning. Drove 3 days in Dallas at over 105 degrees F and it was brutal as I could NOT put up the top due to this error... Read you postings and tried the fuse pull trick first. On my model the fuse cover exists INSIDE the passenger side rear storage box. It is a flush mounted 6x8 " panel and is a bear to remove with your finger nails! Two clips offer positive closure so you must bend them simultaneously towards the front of the car...and pull up. Not possible...almost lost a nail ...of course sweating all over the place in this heat! Will clean that up later. Anyways, I grabbed the pliers from the trunk tool kit and used them to pull the clips once bent. Bingo! Easy Breezy. I pulled the 3rd fuse (from passenger side perspective) which was the only 20amp one nearby...5 secs to allow discharge of any electronics internally and then simply plugged it back in.
The moment of truth...put away the pliers...closed the back tire cover...and closed the trunk lid...and Voila! The soft close snugged up the trunk. Hopped in and fired 'ER up and hit the close roof switch ...it was a thing of beauty !!! All cool inside in 10 minutes flat as well.
Thanks for the fabulous fix Tip...I will give it a week or so to see if the vacuum assembly is OK, if not then off to buy one online and swap it out.
PS. Has anyone found a way to add the trunk lid hydraulic lift/close system? MB dealer says it is like $20K in parts and they do NOT want to attempt it. I had it on my 2007 SL55 AMG and it spoils ya Man!

Cheers!

Also please recommend best sounding muffler replacement for the SL600 as well as any nose body carbon fiber options out there. Thanks.

Is this the part number? I tried to get it fixed under warranty and they didn't get it figure out. I was just going to have the part replaced instead of mess with it.

2004 SL 500 Trunk Lid not closing
 

I did take the closure off and glued all the ball bearings as recommended. The trunk closes every time until I open the convertable top and then the trunck lid will not close unless I disconnect the battery cable and reconnect. Does anyone have a solution.

Trunk problems !
How do I open the trunk with no battery power on consuming battery?How do I charge the battery without coming into the trunk?No engine runing at the moment,and no manual key(03 SL 55)

just wanted to say thanks to the OP for diong this write up! just aquired my 06 sl65 and my trunk started having issues, fixed it yesterday saved me hundreds! thanks!!

Cl 55 Trunk issue
 

Hi I have had endless problems with my trunk lid not soft closing, I have even replaced the trunk latch - but no luck. It works a couple of times and then stops. On the STAR it says timeout or time exceeded. Any ideas?

Did this today on my newly-acquired '03. Red "Close boot lid" indicator kept staying lit on instrument panel, not allowing top to open. As soon as the repaired latch re-installed, everything began to work properly. Just one question, only FMI: the bbs were there to "intermittently" plug the ports, but I'm thinking they were supposed to "float back in" to the ports at times to let air in, or release vacuum pressure. If that is a correct assumption, then the fix eliminates half of the function of the ports. Is there any downrange side effect of doing this? Or just Deutche uber-engineering? -- Also, thanks much, Nick, for this great info!

Here's my new wheels (Sun, 01/27/13, Collierville, TN):

I finally got around to doing this last night and saw that one of the plastic "pipes" was basically cracked in half for about a 1/4". I broke out the JB Weld and sealed that baby up and it works like a champ! Thanks for the info.

Great post, thanks!

I thought reading it would help with my issue, but no luck yet. I've had to install a new vacuum pump and after doing so the door locks and the soft trunk close won't work. I don't think there's a leak in the vacuum system. Is it possible that the system needs to be reset by the dealer?

(Incidentally the radio is also on the fritz and shuts off after 10-15 seconds)

Anyone in the UK / Europe done this that can recommend a brand of epoxy? Don't use Araldite, it just peels off the plastic.....

Excellent post. Many thanks to the original poster. I did this today.

Havn't had any response to my question, but reassembled the mechanism to get the car back on the road, and IT WORKS!!!! Maybe the Araldite is just adhereing to the ball bearings, but what the heck, the trunk/boot closer is back in business.

Many thanks to all involved in this.

EDIT: a few days later. Spoke too soon. Damn thing has packed up again. Left car parked with roof down, and roof wouldnt close cause it thought the trunk was open. Major rainstorm appraoching, so had to borrow a spanner to quickly disconnect the battery, reset the system, and get the roof up. Getting fed up with this now. Havn't had chance to open it all up to see if the Araldite has failed.

2003 SL500 trunk not opening
 

All,

my SL500 occasionally not closing the lid properly, which after following tips on this forum I found a leak on 1 of the ports on the latch mechanism and sealed it and the remaining ports (to be safe) and now it seems to close & lock properly. But it won't pop the trunk open anymore. I've also reset the service battery many times but no luck. Notice, I have to use the mechanical key to open the trunk. Any ideas of why the trunk won't pop open ? Please help.

Many thanks.
ld

NikleinR6
 

Man you really know how to make a post. With the pictures there is no question how to fix this. I wish there were pictures with all recommended repairs. I just purchased a 2004 SL500 and have a lot of the components not working since I replaced the rear battery.

Thanks again.

I have a 2004 SL600. The soft close feature stopped working. I removed the 20 amp fuse and placed it back in a few minutes later and it started to work properly again. I cycled opening and closing the trunk about a dozen times and then it stopped working again. Did the 20 amp fuse removal thing again and it stated to work again, and then after about a dozen open and close trials, it stopped. I removed the unit per some of the recommended threads about gluing the ports, and what I found was a unit that look practically new with no apparent cracks, etc. I did not apply any glue, put everything back together, removed the 20 amp once again and it worked for about another dozen cycles and then stopped.

Any ideas? Seems like the unit works, but for only a short time.

Was it running when you tried it 12 times?

Possible air leak.
 

My 2004 500 SL also has a similar problem with opening or closing the top with the key at the door. I pull the 40 amp fuse behind passenger seat and it works for a few times only to quit again. I am not sure if it is air powered like the trunk. Of course when the key is on in the ignition it works fine with the top switch.

maybe pull the fuse when it's running ., I took mine to the dealer ., they noticed my glue everywhere and said there was no leaks anywhere. It worked for about 2 months after the Dealer gave the system a clean bill of health before it quit. On the left side in the trunk there is the motor/pump that operates the trunk assist and its under another component looks like a black box., I removed the black box, well pulled it to the side it has wire harness attached and accessed what looked like a hyd motor and unplugged it and it lasted about 2 months .., If I just unplugged the fuse and reset it there it only last about 10-12 times as stated above.

Possible air leak.
 

I will remove the fuze when it is running. I still need to glue up any leaks yet. I will be putting it away for the winter in a month or so and might just make it a spring project. Thanks asfast.

I have spent the afternoon fixing my wife's $100,000 car. Be sure to note there are at least TWO different problems. The clip holders on the black diaphragm motor break AND the plastic splits where they push the ball bearings in after the molding process. You must fix both. The black motor needs to be pushed together and held and the splits in the plastic need to be sealed. Do only one and you still have the problem. I have a small pressure / vacuum pump and was able to locate the leaks that way with leak detection soap.

I spent a great deal of time in the automotive accessory manufacturing business and we owned a large plastics molding shop. It looks to me like the design is fine but execution was flawed. They couldn't have passed ISO-9000 design verification and validation with what is on my car. Someone must have changed to a cheaper plastic after the design was qualified. For that reason I strongly suspect that replacing a bad part with a new one would just be replacing a bad part with a bad part. Too bad German engineers never make mistakes. If they did, they could fix them and have a really great automobile.

I need help with my wife's 2006 S500, The trunk switch on the driver door and fob, and the exterior trunk hand switch just stopped opening the trunk and we now have to use the hard key,
the trunk stopped the soft close about 5 months ago and I read the DIY on sealing the latch part #2207500185 and now the soft close is working again but the driver door switch and fob and trunk hand switch still won't open the trunk.

My question is does the rod get pushed from the part #2207500185 with the latch or does it get pulled from the hand switch part #2207501293?
The key tumbler (is attached to #2207501293) for the hard key pulls up on the rod freeing the latch. The MBz service said it is the latch side part #2207500185

I'm sorry I don't know the correct names for these parts but I do know I need to replace at least one of these and want your help to choose the right part.

THANKS!
 

My 2008 SL600 is getting stressed out! I used your posts to replace the third brake light. Ordered and replaced hardware for roof flap hanging down in truck. Removed and epoxied soft close truck latch. I estimate you saved me over $2000! Thanks for a great source for the upkeep of my beloved Mercedes!!!

Charles

Awesome post, thanks for the insight and all your effort.

Great info from everyone, Want to pass along what i found for my situation.
Issue i had glued all bb looking ports, trunk would try to close and then pop up at the point when it would latch, This would happen about 6 times and then stay down, showed boot open, what a few minutes then push down on trunk then ok.
Next step taken was to glue the outside of hockey puck thing that showed cracks.
Now i would keep pop up all the time, after pulling out some selective gray hairs next step was the PSE pump.
Tested latch again and noticed that the unit that opens latch the "hockey puck" looking thing was not retracted back, removed hose from unit and pressure released, removed hose and tested manually latch would now latch every time.
The hockey puck thing would bind the locking function must be a valve not releasing pressure somewhere.
Simple fix i did was to drill a small hole in rubber tube that feeds the hockey puck to release the pressure.
Not the best fix but for now i get to keep some hair on my head before pulling it all out or spending more money to keep this Awesome car on the road.
Hope this helps someone else!!!!!!

First time I have tried to do this hope it works. I have an 07 SL550. My trunk closes fine but will not open properly. TO open it I have to pull it up very hard. Because it will not automatically open the top is also not working. Any thoughts

Excellent post. I am a bit worried about messing it up - is it really as easy as it looks?

Do you glue the ball bearings in place so they won't move?

What glue do you recommend for best results?

Finally, if I can't fix it, do you know what part I should buy to replace it (part number and description)?

I have a 2003 SL500 that has this problem and removing fuse 71 fixes it for about 2 days only, so am guessing it's the leak issue ...

Thanks again for the excellent post and look forward to hearing back on my questions?

Cheers!

I used a 2 part epoxy, worked well.
Ball bearings are wedged in and can't move.
Don't worry, you'll fix it!

Thank you! What brand of glue do you recommend? I have purchased Loctite Epoxy Instant Mix (for metal, wood, ceramic, stone, glass, tile and most plastics) - is this the right type of 2 part epoxy please?

Also - do I actually cover up the ball bearings with a blob of glue?

This will be my first fix job so if I can do it anyone can!! ...but want to be clear that I should cover up the bb's with glue as well as cover up any cracks etc.

I will post back on how easy I felt it was afterward, if someone can just confirm my questions above please....

Thanks again in advance...

Fantastic post guys... I am a total newbie and here is my experience...

- It was really easy to do:-)
- I took my time to make sure I didn't mess anything up and it took me 1.5 hours (you could probably do it in half this time)
- I took pleeson's advice and disconnected both the electrical wires and the yellow air tube so I could remove the unit completely and work on it away from the vehicle
- While I was working on the vehicle, I pulled the 20 amp fuse (71) out and pushed it back in before testing (didn't do any battery disconnects)
- I did not see any cracking or damage at all to my unit - it looked absolutely brand new (I have a 2003 SL500)
- I therefore sealed all 5 of the ball bearings up with Loctite Epoxy Instant Mix... still could hear air leaking...
- Finally figured out the air was leaking from somewhere that I couldn't physically see (but could hear), so just globbed up (technical term!) the area where I could hear the air escaping with a couple of grape sized blobs of glue and firkled (another technical term!) the glue about until it had completely covered up the area (it looked a bit messy, but I cleaned it up a bit as it was drying and in the end it didn't look too hideous)
- I let the epoxy dry for about 25 mins and tested again - the leaking air sound (when simulating closing the trunk) appeared to have disappeared :-)
- I simulated the trunk closing/opening by pushing the locking mechanism latch in and then opening immediately with the tailgate latch opener (repeatedly) rather than physically opening/closing the trunk as I still had the trunk carpet etc. removed and it was in the way
- I had no bits left over :-) and all I needed to complete the job (in addition to the glue) was 2 small plastic cable ties to replace the 2 that were removed

All in all - I would say this is a 10 out of 10 for instructions and a 3 out of 10 for difficulty... excellent! :-)

If you don't see a repost from me in the next month, you can safely assume this resolved my problem ...

Thanks again MBworld - fabulous community/collaboration here - love it :-)

Soft Trunk Malfunction
 

I'm brand new to the site, and relatively new to an R230 (2005 SL500), but I have this trunk soft close issue as described.

Will try this fix soon and advise. Thanks to all the folks that spend the time photographing, writing, and posting this fabulous information. What a country!

Trunk close
 

Hi to all
I had a similar problem on my S430 (2002) but my failure was different.
I removed the opening mechanism from the trunk lid and then noticed that
the "black puck", which is a air operated device, had separated into two parts right at the middle. The plastic catches had broken off allowing the separation, and thus the air to escape. I did not notice any air escaping from the so called a ball bearing vents.
I put the puck together again, and wrapped some bailing wire around it in 3 locations at 120 degrees, twisted the wires to create strong binding, and put everything back.
I has now worked for over 30 days, and it saved me over $800.

Leak on the bottom of the OIL filter housing.
 

Oil filter housing on 05 SL55 AMG is leaking on bottom. Can anyone send me any pictures or instructions on how to remove/replace the seal ring of the filter housing on a 05 SL55AMG?

I am having a problem from last few weeks my driver side door window won’t sit all the way up about 1" lower so when I start to drive the car it says door is open so I did the usual rest and all but it would fail randomly or one time when everything was fine running hour later the burglar alarm comes on obviously thinking the door is open
I changed the driver side door switch thinking it was the problem
Then I did a test by opening the trunk with remote and immediately the window went in correct position as soon as I pressed trunk shut the window went down...

I think I might have the problem as you described I appreciate your effort to explain that thoroughly .I will tomorrow check what you recommended... the beauty of new technologies...
One more note if I did not drove the car for few days and at first start it will have warning Consumer electronic of line (as the battery is not charged one in the trunk) and there is nothing wrong with the battery
2004 SL500

Boot/Trunk latch release permanently operating
 

Help! I have a latch related problem and wondered if anyone can advise me? I have had my consumer battery on trickle charge for the last week with the boot open and now the latch release on the boot is continuously operating so that as soon as I close it it reopens. Also the trunk release button on the drivers door is illuminated all the time. I had not realised that the red button in the rear is an auto close button but that does not operate either. I have had to disconnect the consumer battery as I was concerned the lock would get damaged by continuously switching. Any suggestions for where I should look first?
Thank you.

Nick

Disconnect the main battery; Negative cable first, then positive. Leave it for 10 mins, then re-connect in reverse order. You will have to reset elec windows / sunroof & esp. All should then be fine.

I suggest you reconnect the battery and see if the reset by disconnecting stopped the cycling.
You may try to push the green button on the inside of the trunk and determine if this stops the issue. I am not aware of any other resets.

As to the windows, you have to raise them via switch to the topmost position and then hold the switch for a few seconds. It is described in the Manual how to reset all widows, etc.

Note that you can open all the windows with the remote key, as well as close all the windows, but they have to be synched.

I tried reconnecting after 15m or so but the latch immediately continued operating again. The soft close is also disabled/not working I think.

Hello All, came across this thread couple days ago, and was wondering if anyone can give me some input on my issue..

My Trunk assist about a month ago was not working as described here, it would work when i disconnected rear battery and reconnected it.. then the trunk would soft assist again no problem.. over a month i had to do it about 3 times..

Now my issue appears to be that My door locks do not work either (which are all vacuum related).. brought it to my local MB dealer, they said it was a fuse that blew and it was all fixed, didnt charge me for time/fuse... but now its happening again today, door locks wont lock and trunk assist is like in the locked mode now...

I read through this post, but still a bit confused if this is the problem with an air leak, or if my central pump went bad somehow? Im going to replace the fuse again now once i find but, but any advice would be really helpful if anyone is knowledgable about this issue

thank you

Newbe @ this
 

:crazy: Here it goes! my auto trunk closer is not working at all. After looking @ discussions about this here some say you should hear the sound of air by the latch . I don't hear a thing there. now for the good news' there is good resistance when i use the hard key and pull the trunk open & close it. also after i open the trunk almost all the way if i hit the remote button the trunk goes up a bump hit it again and it bumps up again until its all the way up . Thinks in advance :naughty:

I followed the excellent write up and I have a few things to add.
I took the locking unit out by disconnecting the yellow pressure line. It just snaps out, I used a flat head screwdriver and carefully pry it out. It is meant to be unplugged.

Once I had the unit out, I could see a hairline crack at the end, next to the ball bearing, of the black cylinder that the yellow tube connects to. I also hooked up a MityVac to the opening and it would not hold pressure or vacuum. I epoxied the end of the black tube, and let it cure for about 12 hours.

This is how to test this locking mechanism:

The yellow tube pressurizes the push rod and pushes it out. As you are applying pressure the rod will slowly move out. The rod should stay out as long you have pressure applied. Once pressure is released the rod will move back.

I had a hairline crack at the end of the black cylinder. I epoxied it, using Harbor Freight two part epoxy glue and let it cure for 12 hours. I put everything back together, pulled the fuze out, 20 seconds later I put it back in, and the trunk lid closes smooth as butter.

No other ports were epoxied.
Attachment 376679

Attachment 376680

Attachment 376681

Also you may find that the white clips holding the trunk lining are broken... So I used these from NAPA. Perfect fit, all you have to do is snap the top off and use some sort of pliers to push into its holder:

Attachment 376678

Four days ago I had fuse #71 to blow and my trunk lock would not work and none of my door locks would work either. Pulled the trunk mechanism and epoxied the ball bearing sealed ports. On a 24 hour cure now and will post the results tomorrow. Mine is a 2003 SL500. Don't know why the door locks don't work if fuse 71 is the only one that blew. 9,26,38,41, and 57 are good. Will test the system tomorrow with a new fuse in position 71 and see what happens and post the result here.

Twenty fours later....put a new 20 amp fuse in position 71. Heard something like the air motor run, stop, immediately run again and blew the fuse again. Never have heard an air leak. Frustrated!!!

Trunk Latch Assembly Issue
 

Just the other day I had a similar issue as Nick's original problem, where the trunk of my Wife's 2007 SL550 suddenly stopped working. It wouldn't open in the unlock position with the handle or the remote. I had to use the key, turned completely to the left to open the trunk, and after a bit of inspecting I could hear air escaping at the latch mechanism. Here is what I found.
Following Nicks original post I removed the truck latch assembly. During the removal a few small pieces of black plastic (see below) fell out from the trunk carpet liner, which came from the small air actuated plunger. Apparently over time the plastic becomes brittle enough that the small clips that hold together the air actuated (key-less remote) plunger assembly together break, then separate enough to allow for an air leak, consequently (I believe) the pump will time out.

Attachment 286194
Attachment 286195
Attachment 286196

The bad news was I couldn't repair this with any epoxy or glue to satisfy my anal retentive ways, so I opted to buy a replacement unit from my local MB dealer ($317.00). The good news was following Nick's original post, the replacement literally took me 20 minutes.
Nick great post, hope this additional tidbit helps anyone else with a similar problem.

Hi All, I don't have any soft close function but everything else seems to work spot on. I was looking into this fuse 71 before I attempt to locate it but the fuse chart I have (downloaded online) references fuse 71 being used for multiple systems. Maybe I'm reading it wrong?

What about location, is it passenger side in the storage box?

Thanks all.

Soft Close
 

In my tool kit came a fuse chart, divided into 3 columns for the 3 fuse boxes. scan for fuse in different colums and you will know which fuse box and which fuse. If you don't have proper chart let me know and I will look at mine a give which box and location. Work today but will reply tomorrow if help needed.

Yes, in the bottom of the storage box.
It is fuse 71 (f71) 20amp, yellow.
See the attached photo.
This fuse is solely for the PSE (central locking pump)

Regards

My fuse setup on the 2003 S55 looks a bit different to that. Mine is the 20amp fuse located in the black box with no fuse the other side.

As one of the other guys said, I unplugged the fuse and put it back in and the soft close started to work again for a couple days. It's not working again now. I guess I'll have to try the epoxy fix next...

Soft Close
 

I didn't even know I had a soft close trunk until I read this sticky. I repaired mine just like the instructions and it works perfectly! Thanks for this excellent write-up !

Really usefull tips
 

Thanks for the info , really detailed ? not sure if my 2002/03 has the soft close but will check tonight when I get home :)

Niklein06,
Followed your directions to the tee. After I did everything, had to reset the trunk battery. And low and behold it worked! Now I just hope the gorilla glue sealed up all the air leaks and the battery reset is not just the temporary fix as I read earlier. Great info. One dealer quoted me 1400 to replace the pump or 500 for the latch, but they mostly said they I would have to bring it in first which obviously is not complimentary. Thanks again for the info!

Great post!! I recently had the dealer replace the trunk latch mechanism before I read the forum ($475). Then about three weeks later same issue, trunk would not fully lock. Back to the dealer. They said a new problem. Apparently, according to dealer the storage compartments behind the seat also have a locking system which locks the same as the trunk. They also said there are two thers as well, the center console and the glove box.

So $385 later dealer said they replaced the two storage compartments locks which operate off of the PSE (air pump). Now after a week same issue trunk will not lock, clearly the pump timed out. I performed the simple fuse reset per the post here and now it works. For how long, I don't know. However, the real question for me was this 4 additional air locks operating off the system for the glove box, console and two storage compartments. I have not read any comments at all about these.

Do they really exist?? I will try to check the electronic service manual I have on a computer to confirm but maybe a forum member would have the answer.

BTW, I made sure they returned to me the trunk latch when replaced but forgot to ask for the storage compartment latches. I will inspect my trunk latch for the typical cracking. The one I just replaced (trunk) Was also a replacement from prior owner only 2 years ago.

Awsome!!

I did this on my 2008 SL550 and it worked!!:bow::bow::bow:

Thanks for the detailed instructions!

2007 SL 550 - Trunk Release
 

Hello,
i have a similar problem that perhaps I may solicit some assistance. In my case we purchased the car used and so I am not aware that we have the trunk assit to close the trunk. Perhaps I have two issues, prior to reading this post which has some excellent work instructions by the way - very impressive. My issue is the release, recently it stopped working so in order to open the trunk we have to use the small key inside the key case to open the trunk.

I took the car to MB yesterday and they gave me an estimate of 787.00, 350.00 for the lock and the balance was labor.

If anyone has had a release or opening problem with their trunk and could offer some advise it would be greatly appreciated.

Regards,

Jeff

Trunk lid
 

Thank you for your step by step instructions with pictures on how to fix trunk lid issue.

Question about the fix
 

I was. Wondering after u did this fix by gluing all the ports did ur trunk still open the same meaning via the key and inside and the keyless way or did u have to start opening it with the metal key any info would really help me out

I did this fix and everything works exactly per the original design.

I just did the epoxy repair to my vacuum powered trunk latch on my 2004 SL55. Works great so far! Before I had to disconnect the convenience battery, reconnect and close the trunk to make my top work. Then I couldn't open the trunk or the whole process had to be repeated. This is a wonderful piece of info and saved me hundred$$ of dollars. I assume the OEM replacements will all go bad in the same way so a dealer repair would be a bad gamble. You Rock!

Thanks for the great DIY. I am new to the car and didnt even know I had a soft close. Everything seemed to work fine, no problems with the top or anything. So I pulled the fuse behind the passenger seat. forth one over on the 65. When I did the trunk I could hear lots of air then I knew.

I removed the latch assembly and saw a nice big crack. Glued up all five locations and now the soft close works perfectly.

The only thing I could add is that if you want to remove the entire carpet, open the top first. Then the wings are out of the way to remove.

cannot open my trunk with the blade key is there more than one battery disconnected but didn't reset pump

The blade key should be just mechanical and not rely on anything else. Does the blade key turn? If so, you need to turn it and then release the pull handle as well.

fuse was blown replaced the 20amp fuse was missing one plug on ports in the trunk lid applied silicon and inserted a screw waited overnight and soft top closed works however the trunk warning still is shown and the red light is still lit on the trunk release lever on the drivers side door remote works have disconnected each battery to reset but that does not work also cannot locate the fuse box that contains the rest of the fuses this is a left hand drive car
please advise 2007 550SL

Trunk not closing
 

How do you get the 5 small round push plugs out surrounding the trunk latch. I'm trying to fix the latch mechanism.

Remove push plugs
 

Use a flat bladed screwdriver or a dinner knife, and put it under the smaller
round plug and lift -- it will come up about 1/4 inch:). This will release the expansion and allow you to remove the entire plug.

2003 mercedes sl 55amg trunk latch
 

I've got the latch partially out bot there is a snap to pull out before the latch mechanism will come out so I can glue the air holes. How do you get the snap off?

fixing trunk latch in 2003 sl55amg
 

where is the convenience battery for the trunk locking mechanism?

It's the large battery under the trunk floor mat

Great Pic of your SL55
 

It makes my 2004 SL500 AMG wannabe look weak.:smash:

Ha ha, now another member experiencing my first no trunk close issue. I reset by undoing the negative battery cable and connecting again and that did work; however from what I see here, it seems I may need to get into the process mentioned above to do some epoxy work. But on that first descriptive photo above for those 5 small round plastic clips holding the big plastic piece on, how are those removed? I started to lightly pull on them with a screwdriver thinking maybe they just pop off, but stopped and figured I would ask first, as maybe they really screw in.

Carefully pry out the center smaller piece. I take them completely out. Then pry out the larger outer piece. The small center piece acts like a stem to expand retaining wings of the outer piece. Hope this helps...

Any issues with this Soft Close repair?
 

I've been wrestling with this for five years. It's an issue only at the start of the driving season and I assumed it was due to not having the trunk all the way closed all winter due to the trickle charger cord being there. I blow a fuse or two, cycle the roof and then it seems to be good until I hook the trickle charger back up and the Soft Close can't pull the trunk shut. But I'm game to give this repair a try; any problems now that it's been a few years since you did the repair? And does it make more sense to run the trickle charger on the front battery?

Mine seems to be ok now after reconnecting the battery. I had also noticed that my trunk lights were out, so maybe I just tripped a fuse or something. I suppose if it happens again, then I would be sure it is the trunk fix needing to be done as described here.

Rmk-raven, check my other posts if you just want to run your trickle through the bottom of your trunk. Easy to do. You can either keep the trickle in the trunk and run the cord out the bottom, or have the battery connect coward run through the floor and hook up the trickle on the outside. I have 2 SL did both differently as described.

air plugs
 

thank you for the great post,,
i want to give this a try,, but i wanted to first know how to remove the grey air tube plugs so i can have the whole mechanism free,,
sorry for the noob question,,

Hey, we are all noobs... just differing degrees. :) If you are referring to the gray connectors from the skinny air tubes to the black plastic latch component tubes, the gray connectors just unclip off and press back on. Just be sure to reattach the correct connector to the same black plastic tubes... it helps to take a photo for reference.

followed the procedure,, epoxied everything,, now trunk closes but trunk warning light is on,,
restarted the battery trunk light on and yellow warning light on in dash,,

please,, help,,

Try resetting by disconnecting negative battery terminal, or pulling/replacing yellow 20A fuse under passenger side rear storage bin.

trunk latch assembly
 

I've just replaces the trunk latch assembly in my 2003 SL55amg but still don't get the soft close. Is there a reset button or something that needs to be done before the soft close will operate again?

The easiest way is to disconnect the rear or trunk battery for a few seconds and reconnect it. The pump will then rest.

Trunk Soft Close Problem
 

I have a 2004 SL500 and the soft close trunk mechanism stopped working. I disengaged the battery then reconnected and it worked for a short time then stopped again. I also removed the lock assembly and glued all the ball bearing ports with no visible signs of assembly housing split, reinstalled and stills stops working after a short time.

I then bought a brand new assembly. It worked for about a week and now it has stopped working. Is there anything else that could be causing the problem.

Please help.

Maybe something keeps blowing a fuse or something electrical? I only mention it because when mine had closing issues that one time, I also noticed my trunk light was out too. But when I disconnected and reconnected the battery, all has been fine now for a few weeks with light working and trunk closing.

Jan T: Thanks for your help. I dont think that is the problem because I never had to replace fuses and my trunk light still works, its just that the soft close doesnt. Thanks again.

Garrym: check air tubes connections to latch inlets? There may be a seal(s) leaking. Any burrs on latch inlets? It seems to be a slow air leak causing PSE pump to time out. I had to reinstall my epoxy repaired latch after the first attempt, but all has been good since.

Cygee: Thanks for your suggestion. I will do as you said and will keep you posted.

1985 Mercedes Benz 500sl
 

I have a mercede benz 500sl and I cannot open the trunk. Do you have any suggestions?


Techeddan

My trunk would not open automatically but I managed to open it with the Key in the fob ? Since then its been ok . Sorry that's the best I can advise but there are a lot of answers on the R230 Forum

how did you manage to open the trunk with key?
 

how did you manage to open the trunk with key?

On the main key fob there is a master key , just slide key out of fob and use it to open the trunk. The key goes into the slot next to the number plate lights , next to the pull handle that opens the trunk . Hope this helps :zoom:

Boot / Trunk latch problem or PSE
 

Hi All, I have been looking through this thread and undertaken the route of sealing the BB ports in the latch to no possitive effect. The trunk works for 3-4 soft closes before I have to reset fuse 71 then I get another 3-4 closes. I thought it must be the latch and my cure had failed so I purchased a new latch from MB. Fitted the new latch today and the latch worked perfectly for about an hour (25-30 open and closes) then stopped. Reset the fuse and all ok again for another hour or so?? Pulling my hair out now and $'s wasted if my latch is ok. Is this a PSE fault or another air leak in the system causing the PSE to time out. I do have STAR so can access the CPU if needed. Any help please, many thanks, Ian

It sure sounds like the pump is timing out. Your leak may be between the pump and the latch rather than in the latch itself. I would locate and replace the line from the pump to the latch itself.

fuse location
 

Can you please tell me where the fuse is and what #the fuse is for the pneumatic pump? thanks a lot


moretech

I believe it is in the trunk. It may be near the main pump of the left (drivers side) when you lift the tire cover you should find it.I am doing this by memory but I also think that fuze number 44 behind the passenger seat will also reset it. I think it is a 20 amp. I am still trying to get my lumbar and pulse control working. Also getiing my top to go up and down at the door. It will work once or twice and then stop. Good luck

I just did mine, all 6 ports but I notice when I pull my latch handle I still hear a short hiss. much better than before.
Did I miss something?, I haven't done a reset yet, had 2 bad ports for sure but did not see anything else. all six looked real solid when I put the unit back in the car. lt opens fine, still have my trim off but the rest is together. Not sure where this hiss is from lines red and yellow look brand new. I am not sure if there should ever be a little hiss or not when the mechanism engages when pulling the latch handle
Moretech

moretech... there is a definite sound when pulling the latch, can't really call it a hiss. Do the reset ( I pulled 20A fuse ) and test if the trunk soft closes. Repeat it multiple times, if it works, you should be good.:)

good news did reset and it works
 

:)


So glad to get my 2003 soft close working:) . So good a write up:)
Moretech

Ha ha, I thought I was exempt since my problem with the trunk close was so infrequent a few months ago. However, now experienced two instances over the last few days. But isn't it odd that right after resetting by disconnecting the negative battery that the trunk then closes fine without even starting the car?

tricky trunk
 

only a guess but it may be it has a very small leak that causes an intermittent problem. That is, you'll have to wait it out and see if over time it acts worse and then pull it out and check for cracks. I had to do a couple of resets since working on mine right after gluing but has been fine since. I have noticed it relock itself (engine off) if I DO NO OPEN it within a short period after pulling the INSIDE car release. MAYBE a safety factor?


Moretech

Yeah it has been more frequent recently, so I may be due to pull it and try the glue process. I just find it odd that when I reset it, I don't hear any pump noise or anything and it then closes fine. Maybe it filled with air from the pump before it tripped the fuse, so with reset it already has air in it to shut right away.

I took it out and glued the 6 ports, and for a rookie it took me a couple hours. Buggiest issue for me was getting that ball socket joint off and on. I really had to get my hands way up there and get some force on it. Now not sure if I used the right glue though. I remember the initial post about using Gorilla epoxy for plastic, but when I got to Lowes found only Gorilla 5 minute epoxy that indicated it was good on many things and said "most plastics". They had other epoxy that indicated for plastics, but it was 20 minute set time. I know some of this stuff drips, and I didn't want to be putting on epoxy and holding it vertical for 20 minutes for each port, so I got the Gorilla 5 minute epoxy. When I was done, it seemed like the glue was still kind of soft and kind of rolled off the plastic where I had spilled some. But it did also indicate 24 hour cure time, so I assembled everything back, and kept the battery disconnected to be sure it didn't operate while the epoxy cured. Just hope that was the right glue, we will see.

That's more or less what I did and it has been working great ever since.

Seems to have worked, but over time will tell. In testing it several times it hissed at me once, so not sure what that means. But the red trunk light on the door remains on, and also when arming the car the doors lock, but the lights don't flash. Like some have mentioned funny things happen when disconnecting the battery. Also, people should watch out in turning those alenwrench bolts, as it seems I stripped one.

trunk closer problem
 

I do not think it is closed all the way or trunk light would go out and you would have 3 flashes. It could be ball and socket clamp is not in right position on rod. I am not sure but it may control trunk light circuit based on how far it moves the rod when trunk closes. It was a real bugger for me, had to get extra help from my mechanic to get that darn clamp closed and as high up on the rod as I could get it. I've had no trouble with the lite circuit.


Moretech

You are right. After I assembled everything exactly the same as those initial bolt locations, I was surprised I had problems. First click close was fine but second click I heard it was not connecting fully. So I tried pressing down on the hood to help it. That didn't help so I figured to raise the connecting latch upward somewhat, and that seemed worse. So now I think the solution for me was really to lower that connecting latch instead of raising it. I figure this because if I close the hood one hatch and then slightly lift up, then it closes fine. Would be good to know the correct process to line things up correctly though for others. Maybe the process should be to loosen all bolts slightly and then close the hood, and maybe it would all adjust itself, and the you tighten everything after opening the hood? I would try lower that connecting latch, but that is one of the bolts that I stripped while tightening. So, be careful your wrench is all the way in and don't over tighten.

Word to the wise, or unwise (like me). Pay attention when reading this post, because in the initial post it indicates to unscrew the "hex bolts", which was the mistake I made using an allen wrench on a hex bolt. There is a difference between an allen bolt and a hex bolt, which is why mine stripped easily. Anyway, for a bit of positive, at least I stinkin learned something from the mistake.

2003 sl500 top would not go up, saying trunk open
 

I have a 03 SL500 and one day my roof wouldn't go up, it was saying trunk open, so I unhooked the convenience battery in the trunk for 3 mins and hooked it back on and the trunk open error went away, so I'm gonna wait it out and see what happens. Thank you MBWorld for all your help!! Just saved me some $$ that the stealership would have took.

Yeah, I was in the same boat. Tried to wait and see with mine too, but as time passed it did it more often and so I was kind of forced to try the fix. I even kept a little wrench in the trunk to do the battery since it started doing it about weekly, then I gave in. So time will tell if my fix was good. Probably no harm with you waiting, you will know if the time comes.

Thanks for the reply, yea that's funny I just put a wrench in my trunk too incase it starts raining and I'm far from my house lol. If it happens again I'm just gonna take the pump out and see where the leaks are and patch them up with epoxy glue. I generally try my hardest to not put my top up and down, these cars are fragile and break down sometimes and when they do it costs big bucks to fix, I keep it in my garage with the top down all the time and only drive when it's nice out, it doesn't even see rain, I baby it

Message "close boot lid"
 

I have a 2003 Mercedes 350 SL. Many times I receive the message "close boot lid" on my dashboard.

I check the boot lid which is locked. I open and close the lid a few times and many times the message disappear, other times it continues.

Pushing the button on the the boot lid operates the closing of the door latches.

If I touch the handle button all of the doors lock - hence the vacuum system is working.

It's just when I open and close the boot it regularly triggers that message when I get in the car and start the engine.

Any advice?

"Trunk open error message"
 

Yes I looked into this issue and found a solution, first try not to use your power top and open and close your trunk as much as you can as it's a older car$, the easiest fix it to lift your trunk mat up and on the right side there's a battery, unplug it for a min then put back and it should fix your problem right away. But like I said just try not to play with the top/trunk too much or you'll have to keep unplugging the battery. The problem is you have a slow leak in your trunk pump vac, if you want to fix it the right way you have 2 choices, buy from dealer for around $600+ or take it out but leave the wire plugged in and see where the leak is on the pump buy putting let's say soap on it then put some epoxy glue, let it dry and reinstall and you should be good to go my friend.
Adam Moe.

I read this great thread and took my car to local garage who advised me that the repair (epoxy) had already been done on my pump, so decided to bite the bullet and spent GBP 280 for a new pump. The garage fitted on Friday, but problem still exists. After reconnecting convenience battery, the garage tested and it worked a few times so they assumed fixed. By the time I got it home, had stopped working. Rest the convenience battery and worked a few times, now stopped again, so I assume it was not the pump, but there must be a leak somewhere else?? Any suggestions please guys??
Thanks
Dono

could be the latch epoxy repair is not good. That is, there is a new crack somewhere that is not epoxied. When I did mine the cracks were very fine and hard to see, I needed a magnifying glass to really get them all--there were plenty of them. it's a bit of a pain to pull it but I'd go that route IF ALL OTHER vacuum locks/unlocks in the system check out. if only the trunk lock fails I'll bet on a crack in the plastic housing somewhere. check to see if both vacuum lines are properly plugged into the mechanism! Good luck
moretech

Your symptoms still indicate a leak in the trunk latch pull down system. I would give it another go to make sure the first repair was done correctly.

You mentioned a new pump or a new latch assembly? If it was a new latch, I would recheck if the air tube lines are not split and fittings are fully seated. If it was a new pump, I would recheck the latch for additional cracks and re-epoxy.

Soft close
 

Thanks for all the suggestions. I used wrong terminology. The pump would appear to be ok as all other functions are good. Only issue was boot/trunk soft close, so I have replaced the boot/trunk latch assembly with brand new, so next check is air lines and fittings.
Thanks guys.
Dono

As best as I can find out --At the PUMP the one port marked "HECK" should be the trunk vacuum connection to the latch.


Moretech

HECK
 

Thanks very much!

need some help...!
 

I can get as far as the part where you remove the actual unit from the car itself. I can't find a way to remove the lock mechanism from the trunk lid to be able to work on it...
There does not seem to be a latch to remove it? The clearance to be able to push the mechanism back into the trunk lid does not seen enough.


Help


Joe

Did you go to the very first post on this (about 5 years ago). It shows exactly how to do it and the pictures are great. It really is a pretty easy job.

Joe,
I am thinking you need to release one of the metal arms from the latch assembly... take another look at the original photos, or take a new photo of where you are stuck. You have lots of helpers here.

Just did mine a bit back. you must click and release the ball and socket clamp attached to the rod (it's a bugger to undo) to pull the whole unit down. Then carefully release the 2 hoses. It is a bit hard to release the clamp without long (very) nosed pliers. The pliers can really help to reclamp the unit in place when finished


moretech

My mechanic tried to do the repair using this DIY post. Unfortunately, he tried the gluing part and couldn't make it work. Long story short, I have to buy the part. Didn't want to get it from the "Stealership" so I would like to ask you Pros - where I could get this trunk latch part #2307500185 for my 2007 SL55.

Thanks in advance.

Bari

Anyone? Where do you buy your parts from? Any trustworthy vendor out there?

I have used FCP euro, free shipping, tax, and mbwholesalepartsonline.com. You can goggle Mercedes parts for other sources.

I wonder why the attempted fix didn't work for you. Apparently it fixed mine, at least so far no issues anyway. Wrong glue? Didn't let it set? Didn't fully pile on the glue where all those small bearing parts are located? Maybe try glueing it yourself, or just have another go at it. If you are just fed up messing with it, that is understandable too. I have a low tolerance trying to fix stuff myself, but this process wasn't that bad overall.

Hello all: i used to have a 1997 500sl. Now looking for '07 SL550. I remember the '97 using "air" for locks, trunks, etc. It drove me nuts.

I see they still use "air" in the newer cars. Why do they do that? Electric is the only way to go.

using vacuum
 

It may be in part that the system is "whisper quiet", I don't know.

I call it pure German arrogance

Manual Closing of Trunk
 

So the pneumatic closure feature of the trunk has not been working 100% of the time. I attempted to utilize the manual closing procedures but now the trunk will not close.
Am I correct to assume that by engaging the manual feature I have disengaged any automatic closing of the trunk? i so how would I be able to begin using the automatic closing features again?
:eek:

:)
 

I was able to fix the lock and it works just as it has in the past, the pneumatic closing system still isn't the greatest, but seems to be a common problem for this class.
I had to purchse a new battery since my uncle left the lights on when I went out if town and the soft close started working again, we'll see for how long.

It's normal for the soft close to work again after a battery disconnect and re-connect. However, this is usually temporary since sooner or later the soft close will time out and shut off. This is almost always due to a leak in the latch mechanism or a hose.

I want to second the advice to *remove* the guts of the unit from its housing in order to better cover the ball-bearing ports with epoxy. There are two clips (indicated with blue arrows) that you can squeeze and then slide the unit out (and detach the hose that goes to the hockey puck diaphragm). There are SIX ball-bearing ports to glue (indicated with yellow arrows) on mine (from my 2005 S500 4MATIC). I see some people reporting that there are five ports, but mine has six, and it was hard to tell there were six without removing the unit from the housing.

Attachment 444098

Can a leak in trunk pneumatics affect ABC?
 

Hi Nick,

Firstly, thank you for the excellent tips! I drive a 2004 SL500 and while I have yet to try your fix, the soft close is just one of the problems I'm currently experiencing. Also, let me apologize now as I'm not too familiar with automobile mechanics.

Not sure if you would know but could a leak in the trunks pneumatic system cause a single wheel's ABC system (servos, level sensors) to malfunction? Could it possibly indicate if and where there may be a leak?

After being greeted with a front right lowrider and "ABC Visit workshop!" on a fairly regular basis, my temporary fix was to raise the car then lower it back down and it seemed to be fine. Until the next morning but sometimes longer. I then realized that it only happened when the "Close trunk lid!" warning appeared. (Note: My trunk does not fully close unless I slam it so.. there's that)

For the past two days, I've made sure the trunk was fully closed before parking it and I have yet to come out to a cripple.

Any thoughts?

Thanks in advance!
Chris

I had plenty of problems with my trunk lid closer until I used the above procedure to fix it. The car did not sag though at any time during the weeks it took me to find this forum and this great solution. And the closer is still working perfectly today ( last 5 months). I cannot be sure but now that I've had some time with my new car I do not think there is any connection to the ABC and the vacuum pump. I'm going to bet on a leaky pressure control valve but perhaps it will clear up on its own. You mention it is better now. You might try a fluid change as described in this forum. I have done this as a preventative measure as my fluid was discolored. I have not had any problems with sagging though before or after the fluid change. I hope it stays that way.


Moretech

Trunk assist problems
 

My main battery went dead and I had to use hard key to get into trunk to jump. Now I have a malfunction batteryou light onyears cluster and the trunk assist button stopped working. Do you think disconneciting the convenience battery and reconnecting would resolve my issue as well, Nick?

thanks $300 saved...
 

4 weeks ago took apart the trunk soft close and tried the posted repair.:smash: As a professional tech I wouldn't attempt such a shade tree repair for my customers do to the high probility of a come back. :nix:But for my own cars I'm always looking for an inexpensive solid solution to fixes.

I have got to say :y MB World for this quick fix....:bow:

Trunk assist button
 

When I got home, I disconnected the front battery, let it sit for a few minutes, and re connected. Everything reset and works perfectly again. Thanks for the info. Now I need to clear the malfunction light I'm my cluster. Looking for help on Google before I take it in to clear.

So, I just got a 2003 SL55 and I unplugged the 20amp yellow fuse, and voila the trunk auto closes. I was happy then on the 4th try to close, it stopped working and I can hear the air leaking.

Now, I'm thinking, ah sucks, I gotta fix this now and I'm looking at the pictures and stuff and looks like its doable but.....still unsure of my own handy skills.

The screws on mine in the 1st step looks a bit different. I'm not sure why. I wanna know if anyone has had a failed attempt???

another question is if you guys know if my year SL55 comes with soft close front doors as standard or not? Mine is currently not working at the moment, and I think it probably doesn't even have that function factory installed.

If you are talking about that very first photo, those are just plastic clips that pull out. If you are talking about that photo with the two Torx bolts referenced on the latch, mine were Torx bolts. So if yours are different maybe someone changed them out. But if you do have Torx bolts, make sure you use a an appropriate Torx bit. I mistakenly used an Allen wrench, and striped one of those bolts and then was hell getting it out.

By the way, my fix is still holding up well after all these months.

The battery in the trunk is the convience battery the one located in the engine compartment is the main battery for starting the car

https://mbworld.org/forums/sl-class-...w-fix-diy.html

This link is great showing how to repair

Thank you OP for a great writeup! I did this for my 06 SL55 yesterday. Glued up all the ports with gorilla glue epoxy and after 30 minutes of letting it set, I confirmed that there was no more air leak. I like the suggestion of turning on the pump briefly once before the glue sets in order to suck in some of the glue into the cracks. I disconnected the trunk battery to reset the pump and the trunk worked perfectly after that. However, the red light on my driver's door trunk button remained lit and I also had the associated 'trunk lid open' error in the dash. I tried pulling the fuse from behind the passenger seat, but this did not help. I opened and closed the trunk several times and this also did not help. I was running out of ideas and for some reason I thought I would try the a trunk key. I put the trunk key in and turned it (can't remember if i turned it halfway or all the way) and then the trunk light went off. However, the remote would not operate the trunk and the trunk release handle on the trunk lid would not work. The driver door trunk release would also not work. I rotated the key in the trunk lock a few more times and finally the trunk would work normally from the remote as well as the trunklid release and driver door release. The trunk open error also resolved along with the in-dash trunk open warning. Definitely try this if you are having the error message persist after the repair!!!!!

I also did the trunk strut replacement which took all of 5 minutes and the trunk no longer hits me in the head! $24/each from amazon.

As always, great info on this forum!!!

Okay, so today, I did a consumer battery replacement and the trunk worked for like 2 minutes.

However, I noticed two things. 1) When I drive I always hear a hissing sound of some air leaking form the back of the chair. 2) for the first time, I heard the hissing sound standing outside of the car right behind the trunk and hear the hissing sound even after the trunk is soft closed for seconds after.

Do you think there might be more than 1 leak going on? or am I hearing the hissing of just that one spot where this DIY guide is doing?

Can you hear leaking sounds if the DIY location of the leaks are leaking while driving?

J

I never did hear any hissing before I fixed my latch. I suppose there are all levels of leakage. Mine would work 4 or 5 times after a reset. Now a year later the fix has held up perfectly.

I followed NiKleinr6's excellent instructions and I would like to contribute the following advice. The most difficult part is to disconnect the rod with the cup and ball. You need to reach in and feel for about 3/16" rod. Once you find the rod follow it to the plastic cap. Then use a long screw driver to pop the plastic cup.

Reconnecting the rod is not any easier and you may want to reach in with a drift punch to push the cup on.

My soft close works fine. When I push my close button however, I hear the motor run, but does not move the trunk. Will this fix my auto close?

Thanks for the awesome info, my trunk (boot lid here in Australia) wouldn't lock down....but after disconnecting and re connecting the battery it started to work again. Thanks for the tip and ill be off to get some epoxy asap.
Cheers Jim

I used this process 8 months back and it solved my problem


Moretech

THANKS to the OP for his how to fix it post..

pulled the ground cable from the "consumer", waited a minute, reconnected it and all is now well for as long as it works..

going to look into the trunk lid on my now retired and parting out '01 S600 to see if the trunk soft close part is the same..
and at least have a spare if the one on the SL55 goes bad..

For those of you who choose the fixing/patching route, you can go 1 step further (see pictures):

https://cimg7.ibsrv.net/gimg/www.mbw...79b9d67a4e.png
I remove this part from the assembly (it seems to only have 5 ports with the metal balls) - my car is an 03-SL55, original part I believe.


https://cimg3.ibsrv.net/gimg/www.mbw...15cf51d7d4.png
I went out to my local hardware store (Home Depot) and bought some fuses, and pipe cap!


https://cimg3.ibsrv.net/gimg/www.mbw...5c63d3c60e.png
I broke the fuse glass, ground its end to size. I also clamped the hexagon nut cap, and drilled it to size...


https://cimg4.ibsrv.net/gimg/www.mbw...3f3bced6dc.png
Each time, after I epoxied one end, I cappet it with the right cap, then epoxied over it one more time... Voila!

https://cimg7.ibsrv.net/gimg/www.mbw...343100f9aa.png

https://cimg0.ibsrv.net/gimg/www.mbw...e8327074bb.png

So... I installed the whole thing back in the car (I had not put everything back yet), and it worked great...

However, a couple days afterwards, I noticed some black plastic flakes in the trunk, so I removed the latch assembly to investigate, and found out the so-called black puck was loosing material. I tried to seal it with the same epoxy, and it did not stick. I went out and bought 3-4 different types of sealer, glue and epoxy and it still did not stick (I could seal it then tie it with a hose clamp or cable tie).

All these patches will work, but could potentially break down 6 months or a year down the road, and since the part is original and old, I do not want to take this chance and went out to the internet to buy a whole new assembly. Here is some info about the parts:

My car: 03 SL55 AMG

- Whole Trunk Lid Actuator Switch: A 230 750 00 85 (01 85 for the latest)
www.oemercedesbenzparts.com ($265 as of April 2016)

- Remote Control Vacuum Module: A 230 800 01 78 (Woco 01 2945-013013) (this is the main culprit with 5 ball bearing ends, I cannot find anyone on the market selling it - Only this one need to be changed)

- Air Servo: A 220 800 02 75 (KW16/03 - D108B) – Woco 400292 A/B
(many of you call it the "black puck" - could be bought separately)

- White container: A 220-800-05-75-M22 – Woco 400395
(serving as an air accumulator - could be bought separately)

Enjoy and good luck with all your DIY...!

hlmpk

Is it normal for the " White Container / Air Accumulator tank" to have air coming out around where the 2 pieces of the tank snap together ? Just curious. When I cycle the trunk closer I hear air from that part of the tank. :nix:

If you hear (or feel) a hissing noise somewhere, then there is a leak.
If your whole assembly is old, then change the whole thing - so you don't have to deal with it down the road when something else fails.
If you car is new (5-7 years old) or you think the latch is new, then just fix or change the part that fails. In your case, you can just buy and swap the while container (see part number on my post above).

Just want to remind folks who have a convertible that a working latch is very imperative! When you have your top down, and if it starts raining, and your latch doesn't function (for ex. your car detects a "trunk not closed"), you CANNOT raise and close your top!

hlmpk

For all those asking about having to unlock with the manual blade key-------

My turn in the barrel with my '07 R230: trunk release on driver's door and trunk release button on key will not unlock the trunk. I can use the blade key contained in the battery-powered key fob to open the trunk manually ... insert the key in the trunk lock gizmo, give it a quarter turn, then manually depress the trunk-open gripper and the trunk lock releases and I can lift the trunk lid.

When I open the trunk, stand near it, and depress the trunk-open button on the key fob, I hear whooshing inside the lock mechanism. So ... I guess I have the failure others have cured with applications of Gorrilla Glue or other adhesives.

My car is a full 10-years old ... I'd rather replace the old lock/unlock gizmo than try gluing it.

My question:

What is the part number for the lock/unlock gizmo?

Startech: Many thanks for your prompt reply and the link. I greatly appreciate it.

2006 SL600 not doing the soft close. When you close the trunk it clicks once but doesn't pull the trunk shut all the way unless you slam it. Resetting the PSE will make it work for about 30 seconds. I sealed all the little BB's with epoxy and no difference. I bought a new trunk latch from MB and same thing. What else can it be?

Audiopros1:

I wish I could help you. I ordered a replacement latch mechanism last week when my auto-latch mechanism quit auto-latching and quit releasing using the key fob button or the button on the driver's door ... figgered it was toast. Yesterday I stepped out to begin replacing the latch mechanism and ... Shazam! ... the sum***** was working again. And it was working as of just a few minutes ago ... both opens and closes like it's supposed to. So what caused the hiatus? I have no clue. I'll put the new latch mechanism on the shelf for future use. In the meantime ... if you figger out your problem, please post the solution here. Best of luck, Mate.

Vacuum leak at the pump or the line from the pump to the latch mechanism. Autozone will loan or sell you a cheap hand-held vacuum pump to test.

About the trunk soft-latch: now it's an intermittent problem on my R230.

My car doesn't have the auto-raise/auto-lower trunk lid feature ... just the remote release (switch on door and on key fob) and soft-latch mechanism. I posted earlier that the soft-latch unit had gone t/u and that I ordered a replacement rather than attempt the Gorilla Glue remedy. I have the new unit but haven't installed it because the OEM unit went back to working again ... except when it doesn't.

I hadn't opened or closed the trunk in two or three days. Last time I opened the trunk, I thumbed the button on the driver's door and ... surprise! ... the trunk latch released. I opened the trunk all the way, placed a few items inside, lowered the trunk to the initial latch point, then let the auto-latch mechanism complete the latching. Surprise again. Everything was working properly. I haven't operated the trunk release since then.

I drove to the gym this morning, grunted and sweated for a coupla hours, got in my car, drove home, parked in the garage, sat in the car while the garage door closed, then killed the engine. I neither opened nor closed the trunk. In that period of silence after the garage door closed and I killed the engine, I heard a faint mechanical clicking coming from the trunk ... like something was trying to do something, over and over. I thumbed the trunk release button on the door and the trunk mechanism cycled and released the trunk lid. I opened the trunk, then closed it to the soft-latch point and let the soft-latch unit do its thing. Silence after that.

After that long narrative, I ask this question: what's going on with my trunk release mechanism? There's no apparent air pump or air hose problem: the door latches and seat controls work without exception. The trunk latch either releases via the door switch or the key fob button ... or it doesn't, in which case I unlock it with the key that's part of the fob ... but it always performs the soft-latch process. Always.

Is this a problem SDS can detect and report? I'm a neophyte with SDS. Any suggestion(s) you may offer will be greatly appreciated.

I have read all the posts, as I am having the same issues with the closing assist with my 08 550SL. I did not think it had a soft latch system. I am going to start with disconnecting the battery 1st and go from there.

Emcinnis: I don't know anything about your car's history, but it's not uncommon for people to slam the trunk lid shut, rather than lowering it until the latch connects and then tightens the trunk lid securely. Your car's prior owner mighta been too rough with the trunk lid. If yours has been slammed too much, the soft-latch may be T/U ... I guess a new closing mechanism may be necessary. When you lower the trunk lid and let it make the initial coupling with the latch, does the lid just sit there? Can you hear sounds coming from the closing mechanism in the trunk lid ... like something is trying to work but can't complete its cycle?

I have the auto-raise/auto-lower trunk lid feature. Up until a month ago the lid would click a final time after it was closed. Now it closes shut but does not do the final click and the light on the instrument panel shows that trunk is open. Nothing happens if I push down on the lid as it is closing.

Well I just tried pushing hard on the trunk lid just as it completed the power assist cycle and it is now closed. I tried it again without pushing down on the lid and it again does not close completely. Looks like it is closed, but if I pull up on the lid you can feel a slight give. At least I can close the lid now by pushing hard right at the end of the power assist. Seems like maybe there is an adjustment that can be made, not sure.

It sounds like the latch may be mis adjusted and the pump can't pull it down far enough to fully latch.

The ball and socket clamp must be attached to the control rod as high up on the rod as you can get it after installation. I got a feeling your your a shade off.

I need the advice of Veterans of Trunk Latch Problems.

I put the top down this morning on my '07 SL550. Everything seemed to be in good order. Then I drove across town and purchased some pastries and attempted to put them in the trunk, but neither the trunk release button on my key fob nor the release button on the driver's door would open the trunk. So I pulled the little key out of the key fob and used it to unlock and open the trunk. Then I closed the trunk lid to the first click, expecting the soft-close mechanism to take over from there. But ... no joy. The soft-close did nothing.

So I drove home with the trunk latched only on the first click ... the trunk-open symbol appeared on the dash ... then I opened the trunk with the key fob key and removed our pastries. Tonight I checked the fuse blocks under the hood; no fuses were blown.

So ... where do I go from here? I have a new latch mechanism I've been putting off installing, but I'm not sure my problem is with the latch. Or is it? I do not hear the air pump that powers the latch operating ... so, do I have a pump problem?

What are the steps for troubleshooting this? I appreciate your attention and responses.

Did you check the fuse under the storage shelf compartment behind the passenger seat? It is for the PSE pump, and may have blown when putting the top down.

I would disconnect the trunk battery and reconnect. If the trunk pull down works once or twice, your pump is OK but timing out due to a leak. If nothing happens, then the problem is somewhere else. Do your power door locks work--if so, your pump is OK and you have a latch problem.

Cyglee and Next2pool:

Using a flashlight last night, I checked the fuses behind the passenger seat ... none appeared blown. I'll check again today in sunlight. Thanks for that suggestion.

I disconnected the negative post of the trunk battery, waited 30 seconds (or so), then reconnected: no change in anything.

Power locks do not work.

Thank you for your assistance.

Cancel this post.

Heatwave-Pulling fuse 71 (3rd 20 amp fuse) in the compartment behind your passenger seat for 30 seconds will reset the trunk close assist portion of your PSE pump. The fuse will not be blown, but you have to wait 30 seconds for the circuit to reset. This circuit is designed to save your pump when it runs to long due to a possible leak. I bet that is what your code is about.

Startech: I checked the fuses behind the driver's seat ... I do not see fuses behind the passenger's seat. I like your theory and will give it a try if I can find Fuse 71. It looks like there's a pretty substantial black frame gizmo beneath the storage panel on the passenger's side ... I can't see behind it or in the space to determine whether there are more fuses there. I hope not, but I'll check it more closely. This I know: I can't see anything in that space and I sure can't get my hand in there. Thank you for your advice ... I will pursue it.

Also ... I have a new trunk latching replacement device. I'm going to install it today. I'm thinking the latching mechanism might be t/u and isn't signaling the soft-close gizmo that the trunk lid has been lowered to its first latch position and is awaiting being pulled tight.

I'll post the results of my efforts. Again ... many thanks to all for the advice and suggestions. This is a great forum. But I wish it would quit "losing" my password.

The bottom of the compartment behind the passenger seat is actually a lid to the fuse panel. There are two releases towards the rear that you pull forward and pull up on the lid. It's tough and tight, dont give up.

Heatwave, "I checked the fuses behind the driver's seat ... I do not see fuses behind the passenger's seat." Is your car right side drive? The right side rear storage compartment underneath is where the fuses are hiding. The front panel (held by 2 spring clips) will pop off too, for more access/visibility.

Startech, Cyglee: Many thanks for your offers of assistance. I'm still stumped. Lemme recap this:

Yesterday I opened the top and it stowed in the trunk like it's supposed to.

Later in the day I tried opening the trunk with the key fob remote push button ... trunk wouldn't open. So I opened the trunk with the tiny key stowed in the remote. Trunk assist light was illuminated Red and would not lift the stowed roof.

Today I replaced the latch mechanism with a new unit I recently ordered. I closed the trunk lid hoping the soft-close latch would snug the trunk down like it's supposed to. No joy. Just like before.

I tried removing the stowage box unit atop the cubby hole behind the passenger's seat. That thing is held in with four Torx 30 screws. I got the screws out, but the molding that curves around the rear stowage area had the box stuck in place. I tried peeking into the fuse box behind the passenger's seat (my car is left hand drive ... standard USA).

Using a flashlight, I examined each fuse as best I could ... none appeared blown, but a closer inspection might disprove me.

Startech: you identified the fuse I should check as Fuse 71, the third 20-amp fuse. Is this third from the outboard side of the fuse box or third from the centerline side of the box? Color? I gotta go online and find a fuse diagram.

BTW ... door lock/unlock switches on dashboard don't work. While driving, the instrument panels are red and show the trunk open.

Maddening.

I really appreciate y'alls' good advice and assistance. If you have any more suggestions, please pass them on. Thanks, Mates.

It sounds like to me, you are trying to remove the inner cover from the lid of the storage area. Here is a picture of mine that might help.
https://cimg2.ibsrv.net/gimg/www.mbw...c5c4860149.jpg

Thanks Cyglee, I found 1 of the 2 fuses I dropped! LOL

Startech: It sounds like to me, you are trying to remove the inner cover from the lid of the storage area. Here is a picture of mine that might help.

Thanks for all that, Startech. I'll revisit mine tomorrow. Your picture is most helpful, and I really appreciate it.

Startech: I got to the rear fuse blocks by popping out the stowage box bottoms as you instructed. Many thanks for that ... I wouldn't have discovered it had you not told me.

So I pulled Fuse 71 (it was good, by the way), waited for about 5 minutes, reinserted Fuse 71, fired the car up and tried to raise the top. No joy.

Local MB guru told me to bring it in next Tuesday. This is how $100,000 cars become trinkets in a few years time.

Heat: Are you still getting a trunk open dash message, preventing the roof to operate? Can you slam the trunk closed, and then operate the roof? I might replace that yellow fuse with a new one anyway. If all no go, I'm guessing a PSE pump problem. Keep us posted. Good luck.

Thanks, Cyglee. I disconnected the ground wire from the service battery early this morning. I'm going to give everything the rest of the day to "go stupid," as it were. I'll hook it back up later this afternoon and see if there's any change. And I'll replace that yellow fuse with a new one, as you suggested. Can't hurt.

But still ... on cars this nice and this sophisticated and this high-tech ... simple little things like a convertible roof that won't operate are abominations.

OK: hooked the battery up. No change. Rats.

I don't know how the great minds at MB work ... I was a lowly PE major. But you'd think some bright MB engineer would have looked at the convertible top as it was being designed and engineered and said to the design team:

"Look, sooner or later the mechanism that operates the top is going to fail. Design it so that it will fail in the up-and-latched position. The car has air conditioning ... the driver can operate his car with the top stuck in the up-and-latched position. But just in case the system fails in the trunk-stow position, let's add a simple jack-it-up method for raising the folded-up roof from the trunk and moving it to the up-and-latched position ... something like the process American pickup trucks have lowering and raising the spare tire. Widen the gas cap door on the car's hip ... add a point for inserting a simple tool (stored in the trunk) that, when turned, jacks the roof up and out and allows it to be latched shut."

A car this expensive and so well designed, engineered, and manufactured shouldn't be so vulnerable to a failure that could be catastrophic in a simple little rainstorm.

Another piece of the puzzle: the tow alarm button on the console is inoperative. ABC off/on and ABC up/down works perfectly well. Door lock buttons atop dash do not work. Can't find a defective fuse. Something else I noticed: I disconnected the negative cable to the service battery and left it unhooked for about 8 hours, thinking perhaps that might allow the trunklid soft-close to reset itself and start working again. It didn't. But disconnecting the battery did not cause the audio presets or the seat adjustment presets to lose their memory settings. These are puzzling cars.

Here's the verdict: SAM Passenger Side. P/N 230-900-16-00

All done. Replaced the PSE pump. Makes all the difference in the world. At last ... everything about the Vario Roof and door locking system is in good working order. What's next?

Heat: So it was both a passenger SAM, and a PSE pump? Thanks for posting the followup, so we can all learn.

I don't know why the SAM was faulty. But Xentry kept reporting it as bad, so I replaced it. That made Xentry happy.

Xentry also told me that the PSE was dead. I replaced the PSE pump ... everything works perfectly, including the door locks. The Vario Roof moves more quickly and the trunk release/slow-latch system works perfectly ... all is well. Knock on wood.

Replacement of the PSE pump wasn't too bad. Hardest part was getting the hydraulic pump out of the way ... suspended it with bungee cords. A coupla blocks of air lines lead into and out of the PSE pump. Each block comes out of the old pump fairly readily readily ... plastic clip on the pump holds the blocks in place ... push the clip tab securing each block and it releases its respective block. Remove the PSE pump ... attach the hose blocks to the new unit and install it. Place the hydraulic pump atop the PSE pump. Done.

I plan on dissecting the old PSE pump just to see what it looks like inside. If there's anything worthy of note, I'll try to post pix here.

I'm leaving Thursday for a 2000+ mile trip to Trinity Site, in New Mexico, then to Carlsbad Caverns, back up into Texas to see Palo Duro Canyon, then back home to north Mississippi. All systems in my car are "Go." It better not let me down.

I bought a used trunk soft close assembly on ebay almost 3 years ago, and it finally started to leak and fail. Removed the unit and still had trouble finding where the air was leaking from, even after several sealing attempts with epoxy.

Brain storm: This is a sealed unit, so I hooked it up to an oxygen concentrator I had to provide a constant pressure AND PUT THE UNIT UNDER WATER IN A SMALL BOWL. No trouble spotting the leak location. Resealed with more epoxy and tested underwater again. Sealed now (no bubbles) and put the unit under a garage fan to make sure the epoxy was set AND the mechanism was dry. Reinstalled in car and works great. Just an idea to move things along.

New Problem
 

I've done all the reading, but haven't found this solution yet. I want to know if it can be done.

I have the red warning "Close boot lid." But even closed it still gives the warning, and a regular clicking from the rear tells me that I have the dreaded soft close air leak.

The indie tells me today, after physically getting inside the trunk and listening for air noises, what I already knew from this thread - that the actuator will need replacing.

After we discussed some options, I had a thought that we could seal off the soft close mechanism and have it operate as an ordinary boot. Indie thought this was quite possible and a cheap fix by just sealing up the various hoses.

But will doing this affect any other part of the car?

I don't want to go ahead only to find it stops the roof operation or something like that.

Thoughts please.

There are micro switches inside the trunk latch, that monitor the state if the latch. Probably gone bad, or out of alignment. You would have to take off the latch and take a look.

My indie says there is a hiss which means a leak. But the question I guess is whether sealing the hoses up will cause the microswitches to malfunction?

Great idea.
 

Necessity is the mother of invention and this proves how an easy solution can be found for a complex problem. Great Idea and I will try it today. Thank you.

webuycarnotes: I was a PE major, so I gotta ask ... what is an oxygen concentrator? I don't think I have one of those lying around the house.

Good solution. Glad it worked for you.

Heatwave: I think I may have the same issue as you had. While my trunk lid will operate it does not latch completely causing the trunk indicator on dash to show open and of course will not let the roof to operate. I have been able to close the lid if I slam down just at the end of the power assist. That allows the roof to work, until next time I open the trunk.

What was the part number for the PSE pump? I am not sure if I have a PSE pump, closing sounds more electronic than air. I have a 2008 SL550. Do you know if they changed the closing mech?

emcinnis: The p/n for the PSE pump is:

A 230 800 06 48 ... Vacuum Supply Pump

I do not know whether your 2008 model uses a pump different from the pump in my 2007.

I hope this info helps you. Please let us know how you get this resolved.

Replaced PSE pump
 

Bought my 2004 SL500 about 18 months ago. Love the car, it's a lot of fun and I've learned a lot from everyone here as I've gradually had the gremlins sorted.

The car had the typical trunk not latching problem. Removing the fuse reset the pump and then it would latch, but only for a while. Same with the contour seats. They would give up, seemingly at random.

I assumed it was the soft close and bought a new one. Indie fitted it, but told me it hadn't solved the problem and he was seeing codes related to the seats, but nothing specific enough for him to pinpoint the problem, so he was reluctant to start hunting, not knowing how long it might take and how much it might cost.

The car went back in for a service and some minor work recently. I gave him everything I had learned here about PSE pump related problems and suggested he use a MityVac to chase the problem back and forward from the seats etc. He didn't sound too keen and called me the following day to say everything was done except this problem and he was still getting a generic seat code. I told him to go ahead and pull the seats and start tracking down the problem. I explained that slamming the trunk led to broken 3rd brake light, which resulted in leaks which... you know the story.

Knowing that I was serious and this was more than a minor inconvenience, he put a good tech on it and they quickly - before they took the seats out - found the problem. The leak was at the PSE pump itself and they could hear it. They pulled the pump but couldnt find a way to 'bodge' it, so they replaced it. it was an easy fix, if hard on the bank account.

Having lived with it a couple of weeks I'm sure it was worth every penny to get it fixed and have the soft close working reliably!

If anyone else has problems with this system and assumed it was the soft close, jumped in, replaced it and is still having problem, the advice you can garner from this thread is priceless. Get the codes, put your Sherlock hat on and start listening for the leak from the PSE pump and from the ailing component.

Thanks to everyone here for all the insights and shared experience.

Gary

Has anyone in us done a automatic trunk closer install to solve this problem?

Has anyone in us done a automatic trunk closer install to solve this problem?

Guilty guilty guilty. But it didn't solve the problem for me. I had to replace the PSE pump to get my roof and trunk operations squared away. Your results may vary. Good luck, Mate.

I had a different problem with mine today. The trunk would not open. I'd pull the handle, but I'd hear hissing and the latch would not open. I removed the latch and found the problem. There is a diaphragm that controls the opening of the latch and the plastic where its housing snaps together was broken:

http://benzbits.com/R230/TrunkLatchDiaphragmBroken.jpg

I took it apart to see how it works and discovered it was just those broken plastic tabs that held it together:

http://benzbits.com/R230/TrunkLatchDiaphragm.jpg

Seeing that, I just decided to put it all back together and secure it with zip ties:

http://benzbits.com/R230/TrunkLatchDiaphragmFixed.jpg

All is well now!

Oh, and as an added bonus, with the trunk lid trim disassembled, I took the opportunity to begin the install of my backup camera. Hopefully I'll finish that tomorrow.

Just to add an idea to any others that struggle with this. I had mine repaired twice using this method and although it did work, eventually it failed yet again. As it is a known problem that will happen again and again even on a new part it seems i decided a different approach. There is a permanent way to fool this and have it all work regardless of a leak provided it is small cracking as is usual. I have connected a reset relay in line with the fuse that trips when it over runs. What happens is when the boot motor fires the control power wire to the motor activates a timer relay which goes open circuit after around 5 seconds and closes again. The relay basically makes teh fuse open and closed, same as rest it by pulling th epower. Bought the relay on ebay for 5.00. Never had an issue with it in 2 years now and my boot latch is well fubar. Maybe of help someone on here. The relay is connected in the fuse box area behind the drivers seat where the fuse is that eventually trips.

PS: Dont mess with the electrics if you are not competent and understand currents etc...

Thank you so much! Was told I over packed the trunk which caused the error and soft close to stop working! I reset by removing the negative cable and all is working. I will take in for message check and if I have a leak this post will enable me to make the fix! Thank you!!!! I have no auto
mechanic experience but everyone here makes anything possible! Just completed the vario roof flap fix yesterday!!

2007 sl550
 

Still covered? I have a 2007.

2007 SL 550
 

I am so tired of these dam luxury cars. My second SL and both abc pumps went out and now issues with the convertible top. It's stuck in half open position. Somebody has to have the solution because Mercedes Benz's techs do not. Also, any help on manually lowering or opening the roof. Mines is stuck

If you press the load assist button and the roof down not drop back into the trunk, then it could be a bad switch on the partition cover.

it seems mercedes is not the only car maker who delivers an overly complex car..
try your owners manual for emergency top issues..
SEARCH this forum for answers..
do a google search for "R231 top stuck issues".. which i did and there are many similar complaints..

top hydraulics in wash state has been my go to source for the leaky cylinders on my R129 and will be when the cylinders on my R230 start leaking..

good luck finding that one thing that has stopped your top from continuing its trip to where you want it..

owners of modern cars had better be more self sufficient than my first car, a 1949 chevy de luxe sedan.. :)

Thanks to this forum. Picked up my SL55 last week and, as I already expected, it had the dreaded trunk hiss.

Took everything apart today, and $5 later, good as new!
As the instructions indicated I was liberal with the epoxy. Including the tabs that hold the diaphragm in place (1 was cracked, the others showed early signs of a crack beginning to form). So hopefully this'll last me a decent time. :)

Hmmmm....
 

I'm a little confused as to why the R230 trunk latch is designed the way it is. It seems the ball bearings must be acting as some sort a check valve. Otherwise, why didnt MB design just cap off the ports to begin with. I understand the cracks that occur lead to vacuum leaks which affect trunk/roof operation but i'm not clear that epoxing the "check valves" to prevent leaks isn't creating another potential problem. What did MB intend with these ball bearings? is there an issue that could be created by blocking them off?

j.Chip

My guess is that these ports as used for access to install internal parts during manufacturing. It's easier/cheaper to pop a ball bearing in there than to use an adhesive to glue on a cap.

Rodney any help you can provide. Looking for a manual way to lower my sl550 2007 top. It's stuck half open

Super explanation for easy close trunk!
 

Your article Really hit the spot. I am having that exact problem and will follow your pics and instructions. If I may suggest... you might consider using a yellow text on your great photos since the red text is hard to read. Not complaining mind you. Just a thought. Thanks again.

Fuse to reset trunk soft close - SEE ATTACHMENT for fuse location
 

Here is the correct fuse to reset the soft trunk close on a 2009 SL550. See attachment

Soft close mechanism air leaks
 

Sorry to continue to hash such an old thread. My '04 SL55 has the same problem and I've followed Neil's excellent epoxy fix but I appear to still have a leak within the mechanism that houses the two electromagnets that control airflow to the two actuators. Specifically, internally it's the down-tube within the first electromagnet closest to the pins for the electrical connection. The bottom of the housing has an outlet and air is escaping there while under pressure. I've checked the O-ring seals and they all look good and there are no cracks or anything that I can see. I've sealed all the "ball-bearing" ports and one hairline crack with epoxy. The behavior is that once hooked back up, the pump will perform soft-close on the trunk, the pump shuts off after a few seconds, then about 10 seconds later the latch pops back open (the actuator in the white housing retracts), and the latch is released. During pressurization I can hear the soft hiss of air escaping.

So... my question is: (before I spring for a complete new unit on Amazon for $285), is this 100% a fault in the latching assembly or could it possibly be the pump in some way? I haven't checked pressure between the pump and the assembly (yellow tube), and the pump seems to operate fine in every other way although my seats functions don't work and I suspect broken pressure tubes there.

Thanks for all the excellent help and advice on these fixes. Love the car - had it about 5 months - but dealership prices make my hair stand on end.

Don in Charlottesville

Update: It's been 2 years since I did the epoxy repair to my trunk latch and it is still going fine, so the method can work well and keep working.

moretech

Perfect results
 

great post, worked but only if trunk is open for short duration
 

Guys, great post, easy repair. I followed the instructions and the latch unit did not look cracked and I did not hear any leaking, but I sealed up the bearing areas with plastic epoxy anyway. I tested it, and still did not hear any leaks. Now it works but only if the trunk is open for less than 30 seconds or so. If it is open longer it does not pull shut that last little bit. Any ideas?

I did not take off the reservoir and seal it, the whole unit look like it was in pretty good shape.

Thanks for the input.

I've already had to make one repair on my trunk latch. The housing for the diaphragm that is used for the open circuit cracked, so I fixed it by clamping it back together with zip ties. When I did that job, I discovered that the plastic arm where the mechanical linkage from the handle attaches was broken. Luckily, I was able to open the trunk lid manually one time! After that, there would have been no way to open the trunk! I drilled two small holes in what was left of the plastic arm and used some bailing wire (twisted and locked in with solder) to reattach the linkage. I really intended to but a new latch ($250) but just never did.

Now, I was experiencing the "usual" leak from the closing mechanism by the ball bearings. The pump keeps running and eventually it shuts off that circuit. So, I decided to take it out and fix it. When I did that, I remembered my bailing wire fix and got a bit nervous about what might happen if the pneumatic open circuit failed again, and my bailing wire fix failed. So, I decided to make myself a little insurance policy. I drilled a hole through the trunk lid so I can access the manual release "just in case". Yeah, I know, I should just spend the $250 and buy a new latch, but what fun is that?

One thing i discovered in making this access port is that the manual release lever on the latch cannot be actuated unless the key is inserted and rotated in the mechanical lock. Basically, the linkage at the handle is "locked" and won't move without the key turned to unlock it. So, if you were to somehow lock your keys in the trunk and need to access it by drilling such a hole int he trunk lid, you would also need to disconnect the metal rod from the plastic lever or else the lever cannot be moved.

I had to drill two holes: one in the metal lid, and another in the plastic trim panel. Found a rubber plug for a 1.25" hole in my spare parts bin (a genuine MBZ part to boot!) so that's the size I drilled in the metal lid. I then drilled a 1.5" hole in the plastic trim panel to access the plug. Here are the pics showing the job. Oh, and after I took the pics, I decided to use some touch-up paint on the white edges of the hole I drilled in the trim panel. It's covered by the license plate, but I wanted it to look decent for the next guy that owns the car.

http://benzbits.com/r230/latch/LatchRepair.jpg

http://benzbits.com/r230/latch/TripLatch.jpg

http://benzbits.com/r230/latch/HolePlugged.jpg

I removed the partiion switch and here is what I saw...
 

Hi,
I have an 06 sl500 and recently fixed the soft close by gluing the ports. Then, after fixing that I get a message to close the trunk and my top won't go down. I then checked to see if the partition was in place it was securely in place. Then I unscrewed the torx screw and investigated the right seat of the partition and




this is what I sawhttps://cimg0.ibsrv.net/gimg/www.mbw...2bf53d3dcb.jpg
https://cimg1.ibsrv.net/gimg/www.mbw...d3840de92e.jpg

THANK YOU 🙏🏽 FOR POSTING THIS
 

You will hear an air "hiss" when opening and closing, but it should last for just a second. If you hear air hissing after the latch actuatres, then there's a leak

This is the best advise EVER!!

Thanks! Followed these instructions, and Voila soft close trunk is back operational, closing on its own. I used a gorilla glue with a Small nail brush to glue the ports. I let sit over night, and then installed. worked as stated, u hear a Hissing sound for a Second then it goes away and trunk is tight. I did have to adjust my trunk Latch a couple times, and I marked it prior to removing. Thanks for the Post

Now Here's a Funny Thing...
 

Good day, everybody. I've recently done the 'seal all the holes in the trunk lock' fix, and it's much better, but it does eventually time out the pump. I can hear the hockey puck leaking air, so I'm going to replace that.

However...

If I lock the car from inside using the dashboard switch, it locks very quickly. If I open the trunk using the switch in the car, it opens very quickly.

If I do it using the key fob buttons, it takes much longer - about twice as long for the doors, and at least three times as long for the trunk lid.:nix:

The only thing I can think of, is that the switch locking doesn't lock/unlock everything, only the doors, but I've no idea why the trunk lid should be different, unless with that, too, the key fob unlocks something else as well. I can't think what, though.

Does anybody have any idea why this happens?

Opening the trunk from the key fob does require the button to be held for two seconds. I think it's a convenience feature so you don;t accidentally open the trunk when grabbing the key.

Thank you to all the members who posted. These instructions are fantastic. I started and finished the fix today and everything went fine. Not hard but a little clumsy nkwith all the fasteners, electrical and vacuum connections. You guys rock!!

Thanks a million. Now I don't have to get out of my car to close the trunk before I put the top down. Woo Hoo!!!

Wooow amazing post thanks
 

This is really one of the most common issues of the SL class
just now I understand why every time I remove the fuse and reinstall it back the trunk soft close works again for some time.
Thanks for this detailed and informative post.
really helpful.
do you have any picture of the gorilla glue we should use to fix it ?? If you have please share it with us.
and I have 2 more questions related to trunk issues if anyone can please help.
1st : my car trunk was standing by itself once I open it now it falls down so I have to keep my hand lifting it.
2nd : how to check and refill the hydraulic oil for the hardtop Convertible roof ( I don't even know where this oil reservoir location ).
* my car is 2006 SL 500 R230 japan imported . Left side steering wheel.
thank you again and hope you all the best

To fix the leaks int he trunk latch, use a good two-part epoxy. JB Weld and such will work just fine.

For checking the hydraulic fluid in the vario roof system, see this thread:

https://mbworld.org/forums/sl-class-...-pse-pump.html (Post #10 I linked the WIS docs for refilling both versions of the pump)

https://cimg9.ibsrv.net/gimg/www.mbw...969ec3e2a.jpeg
Active air ports

Mr. Frederick
 

Thank you so much for the information.
really appreciated.

Thanks for the reply
 

appreciating you're kind reply
thank you

OK. I have epoxied all 6 ports. Sucking or blowing on the vacuum line next to it I can hear air moving in this port area (circled). Is this normal or do I still have work to do? Forgive me for borrowing the pic

https://cimg0.ibsrv.net/gimg/www.mbw...3597e98872.jpg

Hi all,

I'm looking to buy a SL350 2004. The top doesn't come up, it signals "Close Boot Lid". Soft close is not working. All door locks, windows et.c. are working properly and the boot lock can be manoeuvered from the key.
Before I pull everything apart, is this fix likely the solution to the problem?

Thanks!

Yes, that is a symptom of the pneumatic function of the latch failing. One thing you can try is to pull fuse 71 on the rear panel for a few minutes to reset the PSE pump. When the pump recognizes a leak, it shuts off that valve. Resetting the pump will make the pump operate that valve again, at lease for a few cycles until it detects a leak. If that temporarily fixes the trunk latch so it fully pulls down the lid, then you definitely need to look into fixing its leaks.

Thanks a lot!
Seller confirmed today, soft close is working after he pulled the fuse. Will pop over to his garage (friends) and try to fix it. Then I'll buy the car.

Another successful $10 repair that saved us $400 in spare parts only. And I have about $9,99 worth of epoxy left for other stuff that needs glueing.. :)
Thanks a lot!

This is a very useful post for repairing a cracked soft close trunk latch. However, I have chosen to replace mine. It seems straightforward but I have questions on disconnecting the pneumatic connecter without damaging it. Does this require a special tool? Is there a trick to it?
https://cimg1.ibsrv.net/gimg/www.mbw...b55fc5c70.jpeg

Thanks!

Guys, I need some help.

This little two pin connector housing broke in half and the wires came loose. The one to the left in the attached photo.
I've got a new connector housing and pins from Mercedes but I don't know in which one of the holes the cables should be inserted. One of the cables is brown, the other one is brown/blue. Don't want to short circuit anything.

Grateful for any help, thank you

https://cimg8.ibsrv.net/gimg/www.mbw...e4876dde8a.jpg

Here's a shot of the connecter on my car with the factory wiring. Does this help?


https://cimg7.ibsrv.net/gimg/www.mbw...124544694.jpeg

Yes, perfect.
Thank you very much, you made my day! :)

Testing the soft close actuator
 

I followed all the instructions about how to repair air leaks in the soft close actuator. Great detailed information. I then decided to test the actuator before installing back on to the trunk lid. I had a standard garden weed killer spray pump (that you fill with water and weed killer). Emptied the contents and removed the spray lance leaving only the hose which I connected to the soft close actuator. Pushed the latch until the first click then pumped the spray pump until the soft close latch moved into the closed position. It held the pressure and was able to determine that all the leaks had been fixed and leave it for a couple of minutes and test again. Tried this six times and worked every time. Refitted the actuator to the trunk and so far, so good, a week later no problems.
Hope this will be of help, saves purchasing pressure or vacuum test pump.

premature closure SL550 trunk
 

Sometimes when the trunk completes its open cycle, it starts closing on its own. Hits me on the head if I am getting something out of the trunk. Ideas?

Welcome to the forum! Please take a moment to visit the User Control Panel and update your profile to include your car model year, and your location (at least country). This information will then appear below your name and avatar on the left side panel next to each post you make. This will greatly help others to give you better information. If you are using the mobile version of the site, you will need to switch to the "full" version to get to the User Control Panel.

So I assume you have the automatic trunk opener where the hydraulics fully raise it? I think there are still some Lift-O-Mat struts use to hold it up and they may have gone bad.

trunk
 

Good thought, although, the problem is intermittent. Also, the closure seems to be an active hydraulic action. Would that fit with bad struts?

Could be temperature related if it's the Lift-O-Mat struts. If it's hydraulic...do you hear the pump running, like it's actuating the cylinders to close? If so, then something electrical must be tripping the close function. BTW, you might want to start a new regular thread of this since it's not an issue with the latch.

wow! I am so glad I found this thread! Hoping for success in my fix!

Successful repair with an unexplained twist
 

Great repair procedure. The oxygen concentrator was a good idea--didn't have one so I used an aquarium air pump. Fixing the unit wasn't the issue--testing it was. Followed the suggestion to test it before total reassembly, I installed it and moved the latch to the first position. The 'open' actuator immediately activated, returning the latch to the open position. The lock actuator would attempt to operate but seemed to bind. I did learn that with the two electrical connectors disconnected the lock actuator would operate if I operated the 'lock' lever on the deck lid. This gave me some confidence that the leak repair was successful.

I finally decided to test it fully assembled. To my amazement, it worked perfectly. There must be a position sensor that keeps the latch from engaging with the deck lid up. Does anyone know if that's correct?

Happened to my 2008 SL550
 

I had been noting this thread on the forum for a long time. It was one of those issues that I expected I would have someday.
When I saw my "Trunk Lid Open" message a few weeks ago, I knew where to look for advice, and it was right on the money!:)

Some particulars in my case:
1) I pulled fuse #71 to reset the message. The problem recurred daily. I reset it daily.
2) When I finally dug into the latch repair, this thread was a lifesaver.
3) I used "Double Bubble Blue Individually Packaged, 2-Hour" epoxy to seal the leaky bits. (Amazon. Expensive epoxy, but fool-proof.)
4) I also managed to break the tiny two-wire connector. Fixed it with the same epoxy.
5) The ball-and-socket connection to the exterior latch was very hard to separate and then even harder to rejoin. I was afraid of breaking the $%&# plastic socket by pushing too hard. Finally, I used a long-handled nut setter to push the socket up onto the ball. I pushed so hard that when it finally popped on, I thought that I had broken it, but it was actually OK.

So far, with several days' use, all seems to be fixed!:)

Are they related?
 

Since I glued the trunk latch, the button on the doors are working, they never worked before?

R230 Trunk Soft Close Problem
 

Hello,

I have a 2009 SL-63 AMG with a trunk soft close problem. The trunk opens and closes with key and interior door panel button, but will NOT close al the way to lock. The red light on the interior door stays lit. I cannot open the convertible top because the trunk is not close completely.

I have read the instructions on how to repair/remove the trunk lock actuator, but I cannot remove the trunk panel because the red lock/unlock lights on the panel won't release. I don't want to break anything, so I reassembled the five plastic snap back in. I'm very frustrated because I cannot even start the repairs on the actuator because of this stupid panel. I can't find any photos or videos that someone has removed the trunk panel with the two red lights on the right sides.

Please help me. I hate to go to the dealership and have this replace when I can repair the trunk actuator myself from your instructions.
Thank you ALL.
Juan

You do not need to remove the close/lock buttons - they can stay on the panel. Once you have removed the five plastic push pins, lift the panel slightly on the right side, then slide it to the right. THere is a single "hook" holding it to the trunk lid just to the left of the buttons.

One more pick of pieces slid apart to seal and replace puck
 

https://cimg9.ibsrv.net/gimg/www.mbw...b88ab0e32.jpeg
Parts pulled out from main assembly
https://cimg3.ibsrv.net/gimg/www.mbw...5c6ad2ba4.jpeg
Part w ball bearings

Has there been any problems with white tank. Should that be sealed?

Mine looked like yours... all tabs were in tact. I did not need to seal that part. But I did test it before putting the interior back in to be sure.

Is there a secret to getting the trunk release rod back into place? I can’t get that ball to snap back in...I even u locked the trunk with a key to be able to adjust the ball up and down...

never mind had to just keep applying pressure at different angles. Finally worked with a flathead. I never disconnected the battery or pulled a fuse and it worked for the ten times I tested it. We will see if it holds up. Thank you for the DIY

Glad it finally worked for you. Next time a little silicone spray lube right help.

trunk closer
 

Glad you got it to work. When I did mine 3 years back or so I had to go see my mechanic friend who lent me a very long nosed pliers set he had and that did the job fine.

moretech

Funny. I don't recall any difficulty putting things back in, after I did mine. The thing just snapped into place. Nah, some things are just inexplicable.:crazy:

Tank plunger not moving
 

---- See next post

Tank plunger not moving
 

After months of continual fuse pull to get the trunk to close properly, I finally took the "plunge" and attempted the fix. When I pulled the latch mechanism out, and tested it visually, I could hear air come from one of the ports and found a crack in another. During the test cycle, the plunger in the tank cycled out and in the tank. After completing the fix, confirming no air leaks from the ports, put it back together and tested again with actually closing the lid. , I could hear air flow, but the second latch cycle didn't occur and the lid did not get pulled closed though I did hear the last typical closure sound from the pump; it just didn't pull down. I removed the latch again, and tested visually. I could again hear the air flow with no outbound air leak. It lasted about 10 seconds. I noted the plunger did not move in the tank during the entire cycle.. All seems to be connected correctly. In checking the plunger, I noticed it is very difficult to pull out as the vacuum in the tank is holding it in.

Any thoughts?

Just a thought, maybe the trunk latch needs adjusted. Could be too tight or loose to finally catch.........sliding it up a few millimetres my help to loosen and sliding it down to centre it. The plastic guides either side of the trunk lid may also throw the trunk lid out slightly which may cause the latch not to centre on the catch, trial and error is the only way to solve this, making sure you mark the guides before you start adjusting.
good luck,
David Hamilton

The latch is catching the initial closure cycle and begins the air flow cycle. It's just not going through the second part of the cycle pulling it closed. I'm using the latch to open it, so it's definitely catching the initial lock position. Isn't the tank plunger also supposed to cycle too? it's no longer moving out...

I think David has a point. It’s unmercedeslike simple to adjust the latch. Just flip out the tiny plastic cover (if it’s still there) to reveal two bolts holding it and try adjusting the latch. And make sure the plunger you’re talking about is not a membrane, before harassing it...

This is a little confusing... perhaps I'm more dense than usual due to caffeine deficiency. The trunk lid is catching the latch (the first stage of closing), then it starts the air flow for over 10 seconds, it's just not pulling down once it clicks on to the latch like it did before the fix after pulling the fuse. After the 10 seconds or more of air flow, you hear the usual reset of the pump (that sits in the lower left of the trunk. The "plunger" is a black rod in the white tank that would go in and out during the cycle before gluing the six ports that have bearings.

You still have a leak. Make sure you securely and properly reconnected all the hoses. Also, pull the fuse to reset the PSE.

I rechecked all of the ports, looking for bubbles... zip, nada... disassemble it entirely and blew through air into the intake tube... and it sounds like the leak is inside the unit,... no air coming from the ports... is that possible? attached is the sound (not sure if that will help)....

That does sound like a straightforward leak! Is the black puck airtight?

The puck is air tight... but here's the thing.... I tested without it connected to the hose to the puck... no air coming out of the tube that connects to the hose and the puck.... when blowing air through the port opposite of the puck tube, it sounds as if the air is escaping from somewhere inside the box ... does that make sense?

I put mine in a bucket of water and found leaks

in blowing air through the intake port, no air is exiting the port to the puck. There is no air escaping from any of the six ports... it appears the leak is inside the box... not exiting through any of the glued ports or the tube that feeds to the puck........

Maybe it's time for a new latch. I think there is actually an aftermarket company that sells just the plastic pneumatic part of the latch for around $50 on eBay.

Looking for experienced help with my trunk issue !

I've removed the pneumatic actuator more times than I can remember to glue up the ball bearings, cracks etc each time it will last a few weeks then I find another crack to glue.

So I bought a used one from a breakers and fitted this, it too cracked and leaked which I sealed up once more. After I reset the fuse, i get about 6 successful soft closes, but then it goes again. I checked for leaks, no leaks this time, reset the fuse and still get about 6 goes.

I've just bought another actuator and fully tested it with leak spray, I do not see any leaks. I fitted it and have the same issue with only getting about 6 goes before needed to pull the fuse. Therefore this is suggesting the PSE pump now? Could it be the impeller needing replacing as I read that they crack
https://cimg0.ibsrv.net/gimg/www.mbw...cd7743f293.jpg
?

Any help would be appreciated.

The good news is that the R231 (2013-) now uses an electric motor for the trunk lock.

The bad news is that it will also malfunction. Mine acts up in cold weather.

nice thread

Hi folks.

I've been trying to work through a problem with my wife's R230 SL500.

After a few months of not being driven, the central locking and all usual vacuum peripherals stopped working, so I stripped the PSE pump and sure enough the impeller blades had shattered.

So no problem, I saw the motor had burnt out so I got a replacement motor and impeller and was glad to fix the PSE issues and the seats, central locking and boot soft close started working again.

However, even though the boot now shuts no problem it can only be opened by the manual key and not the remote key or the release button on the drivers side door - it's as if the vacuum to shut the boot "is" working (as i can hear it) but the release is not - i tested this by taking out the mechanical locking mechanism, and when i push the teeth they shut but I can't get them to re open unless i use force.

Any suggestions where to look? i have glued the ball bearing ports on the mechanical lock, that doesn't seem to have made any difference (thought it might be a vacuum leak.)

Does a particular part of the lock control the release?

Hello all, I have a 2009 SL550 sport with auto shot for the trunk, last few days I have to assist the trunk to shot while it is automatically closing or warning light will tell me that it is open.
is my problem the same or mine is hydrolics?
thank you
ben

https://cimg4.ibsrv.net/gimg/www.mbw...946f4572f.jpeg

2009 SL 550

A few things adding up....before I start the troubleshooting....first thing I noticed was the center console would not open, then noticed the top would not go down (partition warning), then noticed the trunk would not open and locks do not work. But ultimately I had to open the trunk with the valet key and now it will not "self close" suck down tight. Same on opening, it will hum but will not unlatch and open.

Is this more than likely the PUMP it self vs. the trunk latch, since all all the components seem to be effected? Or, can a leak ANYWHERE cause problems with the entire system?

I've had zero problems the last 2 plus years since I've owned the car, 31k miles currently. I have run the battery down now and again when I forget to plug in the trickle charger. So I've had those gremlins, usually cured by a long drive or just using the charger over night.

So I have NO blown fuse.

Battery IS fresh.

Central locking not working at all, nothing.

Can the PSE just quit without blowing a fuse?

Great Write up and Pictures..... Thanks Brother
 

https://cimg2.ibsrv.net/gimg/www.mbw...ba6fef4aa7.jpg
Trunk with liner and actuator removed
https://cimg3.ibsrv.net/gimg/www.mbw...04c7e77a61.jpg
Close up of were actuator mounts
https://cimg2.ibsrv.net/gimg/www.mbw...810d3fa16b.jpg
Actuator assembly out of the car
https://cimg6.ibsrv.net/gimg/www.mbw...4f8c79e1ad.jpg
Close up of actuator assembly
https://cimg7.ibsrv.net/gimg/www.mbw...c9a05e7e54.jpg
Where I epoxied
https://cimg8.ibsrv.net/gimg/www.mbw...12166a9251.jpg
Where I epoxied
https://cimg0.ibsrv.net/gimg/www.mbw...938cfe0b1b.jpg
Where I epoxied
https://cimg3.ibsrv.net/gimg/www.mbw...c82a5c0e4b.jpg
Where I epoxied

even though i have read every forum post i could find...i am stumped with my pse and soft close. did not know i had a trunk closer, and just slammed it. everything continued to work. jut finished a strutmaster conversion...nightmare...and found the fob , locks etc. no longer worked. fuse 71 was blown...new fuse...everything worked again until a soft close. fuse blown again.....no reset...just blown. accessed the pse and tested each line. the only one that a hand pump would draw any vacuum was the gas flap, but it quickly went to zero. i have a small medical aspirator pump, and was able to pull 20 inches vacuum on each line, but all slowly went to zero. when i pulled the central locking line it had positive pressure. i find it hard to believe every line leaks. the car has only 21k and looks almost showroom.
if i just manually shut the trunk it appears that everything else keeps working. i have not yet opened the pse because the line tests brought me to complete confusion.....a short trip.
i believe all lines are supposed to hold vacuum. i have not gone after the closer mechanism yet because it seems nobody else has had the same symptoms. don't want to fix it if it ain't broke.

Are you sure your PSE pump is OK? If it was faulty it can cause the fuse to blow

pse apart looked pristine. read somewhere on these forums that a guy in the uk bench tested several pse motors with no load. many of them drew near 20 amps. so, they use a 25 amp fuse. i tried it and fixed the fuse blow problem. however, the soft close only worked for a bit after each fuse pull reset. pulled the latch mechanism, and sure enough i could see a couple of hairline cracks. also the hockey puck showed one cracked closure bit. i'm off to get some quick set epoxy. i already have jb plastic weld, but it is a 15 minute set....getting the 5 minute gorilla epoxy. so, between the fuse and the epoxy all should be good.

after taking a good look, this should only be done on the bench, and the unit quickly removes from the whole assembly....exposing all 6 of the ports. i intend to cover the whole tubes...and the equator of the hockey puck. also, i intend to degrease all surfaces with carb cleaner or something to insure stick.

safety trunk feature
 

Hello guys, searched in the forums but couldn't find similar issue. My GLC 2020 have the auto / assist trunk close (the one with gesture for the foot and also the red buttons on the trunk). My question is that i know the trunk have a safety feature whereas it will stop if there is any obstacle during the closing process in order not to cause injury or trunk malfunctioning. however, in all my previous cars, even low cost one! the trunk used to re-open by itself when this happen to allow the user to remove any obstacle. but in the GLC it just stops and you need open yourself. If you press the close button again, it will try to close and the same issue reoccur.

i have a scheduled maintenance in 2 Sept. for many issues in the car and this one is on the list. just wanted to see if it is common or even an issue to start with!

thanks.

Don’t know if this helps any UK members but I’m struggling with fixing the boot soft close at the moment. I tried the epoxy fix without any success. I then started thinking about trying a second hand replacement mechanism but quickly gave up on that as the prices are very high. Probably SL “tax” lol.

During research, I discovered that the W220 S Class also has a soft close mechanism. It’s not the same as the R230 as a whole, but............... the solenoid mechanism inside the S Class mechanism is identical, so it can be removed and installed into the R230 mechanism. Why is this useful? Well on UK eBay the S Class mechanism is available second hand for approx £35 from Eastern European breakers as opposed to the circa £200 that breakers are asking for the SL mechanism. So buy a complete S Class mechanism to get a relatively cheap solenoid piece to play around with.

:zoom:

A very huge Thank You -- for this post --
 

So I never much respond to these posting but in this case it most needed -- I spend numerous hours trying to figure out the problem with my SL600 soft close trunk action. it would close but not latch totally shut. I replaced the switch as per the WIS manual but it still would not work. I would have never guessed to reset the convenience battery to get the new switch to work --- and had I seen this posting sooner I would have saved the money for a new switch and repaired the old one -- a life saver and I much appreciate your posting -- Thank you again for this it was extremely valuable -- not money wise but also knowledge wise ---just perfect
gsones

A very huge Thank You -- for this post --
 

So I never much respond to these posting but in this case it most needed -- I spend numerous hours trying to figure out the problem with my SL600 soft close trunk action. it would close but not latch totally shut. I replaced the switch as per the WIS manual but it still would not work. I would have never guessed to reset the convenience battery to get the new switch to work --- and had I seen this posting sooner I would have saved the money for a new switch and repaired the old one -- a life saver and I much appreciate your posting -- Thank you again for this it was extremely valuable -- not money wise but also knowledge wise ---just perfect
gsones

2003 R230 - Trunk Latch Handle Does Not Open Trunk
 

I recently replaced one of my Vario Roof actuators - so had the vario pump pulled to the side to access the hydraulic lines associated with the actuator. Prior to this repair my trunk latch handle and soft close feature both worked flawlessly. After the repair, the trunk handle will not open the trunk - there is absolutely no resistance when you press the handle. I can however open the trunk using the hard key. Here are some facts I hope help narrow it down:
1) Trunk will open using hard key - when closing the soft close does not work.
2) The Vario Roof actuator I replaced was the one directly behind the PSE pump - fluid was leaking profusely near and around the PSE pump.
3) I failed to disconnect the consumer battery before replacing the actuator - had a couple of electrical lines that I believe tie to the internal safety button for opening the trunk spark a bit - I have not checked any fuses.
4) The Key Fob will unlock the doors but will not open the trunk
5) The drivers door trunk button will not open the trunk

As I said - absolutely no resistance when pressing on the trunk handle - looking for some thinks to check hopefully in a logical order that reduces the tear apart as much as possible.


Looking for possible causes for the trunk handle to suddenly stop working - here are a few known issues I encountered during the Vario Roof Actuator Replacement:

On a car with so many computers it's never good to have wires unexpectedly spark. I would check fuses before anything else. There's a good chance you blew a fuse with that spark. I don't have the R230 fuse charts handy but I can dig them up if you need them.

Just to confirm: does the roof now open and close properly?

The grip on the trunklid is an electric switch, so without the metal key turning the lock cilinder you won’t feel resistance there. There should be a click, though.
Relevant fuses you’ll find behind the right hand seat under the bottom of the box.

Have you tried slightly adjusting the latch via the two screws?

This video shows the operation of the latch click and how to do it with example of where a leak is found.

I know it has been said a new PSE needs to be programed to the car with Star. Do you also need to program a new soft close trunk lock (#230-750-01-85) to the car?

Maybe it's time for a new latch. I think there is actually an aftermarket company that sells just the plastic pneumatic part of the latch for around $50 on eBay.

A link to share for this product ? Thanks

The equivalent S Class has a slightly different lock, but if you examine it the actuator part is the same, and can be separated and put into an SL mechanism. The price of second hand S Class locks is a lot cheaper than SL ones.

So, thanks for this good idea.

Is it possible to close manually the trunk and to open the roof automatically before to repare the mecanism ?

Offer on ebay new part :
https://www.ebay.com/itm/Trunk-Latch...e3b81ece30d9c3

I have a 2003 CL600 with a automatic trunk latch that stopped working. Is this part a fix for my problem?

I will answer my own question: No it does not need to be programed.

Any suggestions where this pump is on an R230?

Thank you for excellent post! I scuffed-up the plastic areas & sealed with Crazy Glue & Baking Soda. Hard as a rock & ready for testing in seconds..

It's in the trunk on the lower left side...
See other posts here..

I just did mine again.

The best advice I would give anyone repairing their boot lock is don't use epoxy. It gives the appearance of grabbing tightly on to the plastic but doesn't really bond; you can pick it off the plastic where it sort of peels away in a lump.

One of the pieces I had glued a year or three ago had come loose off its end and caused a leak.

I used Loctite Prism 480 cyanoacrylate and fast spray activator this time on all six tube ends (there are six - don't miss one) and now it seems to be perfectly airtight.

I just looked up the baking soda and super glue technique which should yield similar results.

Yes! The super/crazy glue w/ baking soda technique is awesome & worked for me too!

Am I crazy for just replacing the leaky part..?
 

Hello everyone. Summers here and time to drop the top. My soft close function works only sporadically, like many of ours….ugh
ive read all of the solutions and attempted solutions here and have concluded it’s best just to replace the leaking part. Does that make sense….just not technically inclined nor open to continual frustrations!

You thoughts please?

Well, we're all different, and if you don't have those sorts of skills then you're locked in to either getting an MB dealer to replace the lock, getting an independent to replace it, or getting someone to remove and repair it, with the third option being the most logical. It's a pretty easy job, but read my comments about not using epoxy on the leak points.

Option one or two are going to be expensive. Option three you can do for the cost of the cyano.

This is a great thread but I have a question for those who have done this. I have the latch assembly out and am testing for leaks. The only air i feel or hear is coming from near the side of the latch itself not anywhere near the ports with the ball bearings or the "puck". Is that normal or should any air leak be attacked and plugged?

Apply Crazy Glue then sprinkle with Baking Soda. Hard as a rock & ready to go in minutes...

Air should not leak from anywhere....

If you can connect a low pressure air source such as a bicycle pump to the air inlet which shouldn't be too difficult then you can put a few psi of pressure into the lock.

Mix up some dishwashing liquid in water in a spray bottle, spray it around the lock and watch for the bubbles. You'll find them pretty fast. However all six ports where the ball bearings are pressed in should be glued up with cyano as a matter of course - don't bother reinstalling the lock unless they're all glued up.

Good morning. It’s a bit surprising to see how many of us are afflicted with this issue, but heartening to also see how many of us are willing to tackle problem personally. I know the limitations of my technical skills and decided to have my independent Mercedes specialist just replace the unit, $500 total. Best $500 I’ve spent recently, gives me peace of mind on the road that if confronted by rainstorm I can raise the top reliably.

This is a great thread! I removed and fixed my latch mechanism. Mine was leaking not from the ball bearings my leak came from the side of the latch itself. I sealed that AND the ball bearings with JB Weld epoxy. Works great. This is rteally a very simple project. Thanks to all who hav eposted to this thread over the years!

I've been trying to fix the soft close on my boot latch for months. I've tried two different types of glue. Leak tested twice with foamed washing up liquid. Every time I put it back it works for anything between five minutes and several weeks. I was certain I had fixed it after the last time three weeks ago and it still worked yesterday evening. This morning it's stopped again. I think i need to give up.

I’m sympathetic. Sorry
I recently had my independent Mercedes’ shop replace the thing, $500 parts and labor. Very happy I did. Everything works flawlessly now

Thanks to all who contributed to this thread. I epoxied my ball bearings and also the hockey puck needed epoxy repair as well. Now the soft close is working on my 2004 sl600. Wish it had power trunk open and close but that seems to be cost prohibitive or not really possible.

funny thing with the fuse is the order on my fuse block did not match others who posted. I looked at the amperage and eventually figured out which one to pull based on that and the pump reset no problem. So for those who could not get the pump to reset by pulling the fuse, check to see if your fuses are in the same order or not. The fuse blocks are color coded and seem to be able to be moved.

does anyone know the part number of the latch? I'd like to buy one and install myself as I'm having the same issue.

What a great thread. Thanks to all.

Since I had this problem too, I did the project, but mine was a little different. It was obvious the lock assembly had been replaced (tye-wraps were gone, new looking, no cracks), but I sealed the bearing holes anyway for the future. I also thought a little epoxy on the surface near the end would slow the escape of plasticizers and maybe extend the life of the part.

In the past, the electronic fuse tripped the fuse 71 circuit, seemingly when I left the lid slightly open for a while, and the red light on the drivers door came on, like everyone else. Pulling the fuse for a short while always reset the electronic fuse, like everyone else. But here is where the gremlin snuck in after the "repair". Although the soft close worked as it should, the red light came on anyway and refused to be affected by fuse 71. But, the soft close still worked. Then a little later, the red light went out. This seems to be an intermittent problem, maybe a sensor right on the edge. I am assuming if the light is on, the top will not function, so it is imperative to find the gremlin. Any ideas?

I am wondering if I accidentally moved whatever it is that signals the lid is closed. What and where is the switch/sensor that tells the computer that the lid is closed? Anyone know?

Also in this process, I failed to figure out what the long contoured rod that connects to an arm with a snap ball does for the system. It is possible that is the source as I had difficulty with it? Anyone know?

Sure hope someone has the answer as I now have zero confidence in the reliability of being able to move the top.

Have Trunk Soft Close / Trunk Assist problems. Here is how to fix DIY
 

Hello again. I'm waiting for my PSE replacement impeller. Meanwhile, I put the repaired air controller assembly back in the trunk thinking I was done with it. Now for some reason my remote won't unlock the trunk lock- something that had never happened before. I tried to manually open the trunk using the key and that wouldn't work either. I have the trunk in the service position because I need to replace the right load assist cylinder. I decided to remove the inside trunk cover so I could see the relationship between the air controller and the key lock mechanism. Here is where the linkage comes into play. When reinstalling the air controller assembly I had just put the linkage in any way it would go - not a good idea. At this point I would say I don't think I could be assured of putting that linkage back in the car correctly if I didn't do it from the rear. I had to adjust it from the beginning to get the key and trunk handle to open the trunk like it is supposed to. Now if I could just figure out why my remote won't unlock the lock from the soft close position as it had been doing. The PSE pump works so I'm thinking the wire connectors on the air controller are not working properly because I am getting no air to the air controller when I push the unlock button.

I think you mean the part that enables you to open the trunk, using the key (turn the key, hold it there and pull the grip).

I know your post is old but I just found identical pieces of plastic fall out when I removed the latch mechanism. Where did they come from - I can’t tell and seems the only option is a total new complete mechanism? Thanks

The trunk locks without the soft close and the top will operate fine. You just need to close it with more force. Both hands on the left and right side and slam down. It will lock. I’ve been doing this method for years now.

My mantra: slamming the trunk lid may eventually crack or dislodge the 3rd stop light. Water may seep into the trunk lock, affecting the electric parts in there.

The plastic pieces on the photo's have broken away from the puck. That may cause the puck to leak air. Strap the puck tightly with tie wraps. I did ead that worked for Rudeney,

Took a working SL 550 (2007) trunk and decided to epoxy the ball bearings.

Everything works that I can tell. Including the 2nd latch. It opens fine and closes fine. My door locks are quicker.
I disconnected the trunk battery for a few minutes and pulled the 54 fuse (20amp). I pulled and reinstalled the latch mechanism and all seems right.

But the car is convinced my trunk is open (it is not). I can't raise the top and I get a red light when moving more then a few miles per hour.
Any other ideas to try?

>>> quick update and hope this helps someone. I don't remember doing this but i had the trunk set to valet (manual key). Somehow in the process of me trying to figure out how it all works probably.

And you can't raise the top in valet mode. Anyhow I fiddled with the manual key and latch and something got jiggered back to where it was supposed to be and voila. It seems to work. Hoping not going to be an intermittent issue but seems good so far.

I'm dong this repair now. Found a leak in exactly the same place as everyone else. But when I tried to disconnect the yellow pipe connector, the barb broke off inside the hose. Does anyone have the part number of those grey pipe connectors? They are a real fiddle to undo without breaking.

https://nemigaparts.com/cat_spares/e...fg/230467/65p/

Try section 80 and then section 45, item 70. You'll need to make sure, though

Better still, get WIS on your computer.

Fantastic. Thank you. I have bookmarked that site. Very useful.