ChesapeakeLimo

I have a 2010 S-550. Some time ago this happened intermittently and now has become more prevalent...

I close the trunk lid using either the door switch or the red button in the trunk lid and the lid closes and I hear some kind of motorized noise for 3 cycles and then the lid pops up slightly and is unlatched. I used to be able to activate the exterior (above license plate) or interior emergency (inside trunk lid behind license plate) open button and it would cycle the latch mechanism 3 times and then it would close and latch/lock properly. This remedy seems to be less and less effective.

I am wondering if anyone else has experienced this phenomena and can offer a resolution?

Popo Here

I used to have a similar problem with my 2006 S500 which was a W220. Turned out to be a wire harness problem. Not sure if it would be the same with the W221 S550

ghetto_games

Going through this right now. Sometimes trunk will close and open right away, just like yours. I have to hold the manual trunk release open to get it to finally latch (sounds like I'm breaking something).

Sometimes everything works perfectly. Most times though, none of the buttons work, trunk release button in the door, auto close buttons in the trunk.

Sometimes the trunk release in the door or the manual trunk release on the trunk itself will result in opening the trunk, but not the assisted opening and closing.

Searching through other forums, some people have narrowed their issue down to a leak in the trunk latch - https://mbworld.org/forums/sl-class-...w-fix-diy.html

ChesapeakeLimo

That references a 220, which is a different setup from the 221.

I've acquired another electronic latch to install, along with a new set of hold down springs. Once I install them I'll update this thread to let you know the result.

DaveW68

Actually, the 220 and 221 have the same mechanism.

ChesapeakeLimo

Well, I did replace the electronic latching mechanism with a used unit, but I still have the same problem. What are the odds I got a used unit with same problem? Thinking it may be something else causing the issue...BUT WHAT?

marthyh

Have you checked the actual button on the right side of the middle,there it has an actual square with rounded edges button. I had the same issue with mine: then by applying this button,it sort of resetted the mechanism of the actuator; it made some mechanical noises,after this I was able to close as usual.Its not the handle that opens the trunk but right next to the reverse-cam.

ChesapeakeLimo

I'm confused as to which button you are referring to. Is your car a W221 (07-13 S-Class)?

If so, if you can snap a photo of the button you are referring to I can check to see if I have such a critter there.

ChesapeakeLimo

It's definitely not a leak or low fluid in the hydraulic closing mechanism. I am thinking I have a problem as the (red) trunk closing switch that may be shorting/open intermittently when the trunk is 1/2-almost closed. I've ordered a new switch and female leads and connector. Once I complete that repair I'll update this thread.

1bad540

my friend had this issue on his 07 and turned out it needed to be reset thru the computer. (at the dealer). sounds like a programming issue. stop changing parts!!!

ChesapeakeLimo

So, I did replace the electronic latch mechanism. And the trunk now closes on the first close without any intervention. However, now I have a new issue with the trunk:

The trunk will not auto open with either the latch release above the license plate, nor the trunk release on the driver's door, nor the remote key fob. I have to use the metal key to unlock/unlatch the trunk and then I can use any of the aforementioned components and the lid will rise automatically. The lid will also close and lock from any of the aforementioned triggers. I know there is two positions for the key and the key tumbler is NOT in the LOCKOUT position (it's parallel to the bumper position.) Everything else works just fine. So, I'm half way there?

I did some research and found that there are two modules that are integrated with the trunk; an opening module and closing module. There appears to be no way to diagnose if either is the culprit if any at all.

I am uncertain if there is a reset procedure that one might know of or any other diagnostic things I might try to resolve this problem without having to visit a dealership with a STAR diagnostic computer?

One reply mentioned about a square with rounded corners between the electronic latch release and the reverse camera, but I can assure you that the 2010 and later W221 do not have this 'switch' component. There is a blank there that looks like what was described, however, upon dismantling the trunk lid there is no electrical connector to it. Apparently, when MB re-engineered the trunk and lid, they did away with that component and created this 'dummy plug' to install so they didn't have to re-engineer other components?

All input is appreciated.

mnje350

So I tested the trunk close function from the fob and it does in fact close the trunk if you hold the button a few seconds. Mine is an early build 2015 model. Pretty cool although I don’t know when I will ever use this feature. It’s not really a problem to reach up and push the button to close the trunk.

KBH

Have no idea if this works with the new design... but...

Intermittent trunk operation (and eventual death). I had this issue (2007 E550). Thought it was a leak, maybe. Decided to do a reset and see if it worked. Took out the trunk panels, etc. The reset (unplug and replug) seemed to start it back up again, but it was shortlived. Then I moved around and touched a bundle of wires by the back left hinge and hear the motor 'come alive.' Turns out a wire was sheering/was cut under the (very tight factory) zip-tie. Repaired wire and trunk has been fine since (14 months after initial onset, but only about 9 months post-repair). There's a youtube video somewhere that shows the issue (which I found months later).

SpookyTheFirst

Edgar Perez

Hey guys...Check the connector on the right side of the trunk lid latch mechanism. If that connection gets loose or is pinched behind the trunk lid latch mechanism the car believes that the truck lid is not closed. I experienced the same thing on my 2005 SL500. When repairing the mechanism. Pushed in connector and ensured there was some play in the wire. Everything works great now. I also was not able to close my convertible top, :-)

Attached is pic with connector. On my 2005 SL500 I have a lever to open the trunk on the driver's side door. (Pic 1). A Red LED light will turn on @ the lever when the trunk is open or you pinch or disconnect the denoted wire on the trunk latch. (Pic 2). The way I tested this was to open the trunk lid, depress the actual latch with a screw driver until in goes to it's farthest point...to simulate that the "soft close" latch has completely closed the trunk. Check the connection of the wire...if it is fully connected the red led in your door should turn off....if it's loose or pinched behind the latch mechanism...the red LED will be on...and you will get the "Trunk Lid Not Closed" message on your dash. If that wire is connected properly...car will believe Trunk Lid is closed. After you get LED to turn off...make sure you depress the trunk lid handle to unlock the mechanism before you close the trunk. Let me know if it works for you! Thx! Edgar

Pic1 - Trunk Latch Wire
https://drive.google.com/file/d/1VSg...ew?usp=sharing

Pic2 - Door Lever & LED
https://drive.google.com/file/d/16P1...ew?usp=sharing[/QUOTE]
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IAATM

Thanks! Can you snap a photo of the connector in your car? Or maybe a wiring diagram? Just want to understand which connect, where it's located, and how to access it. Thanks again.

Demetrios Tom S

how much do they charge any clue ?

garage6054