LADYBNZ

Greetings all,

My trunk release recently quit working with the key fob, drivers door switch, and emergency release in the trunk.

It does the classic "whirrr" sound but does not release the latch.

I know that I can use the manual key and turn counter clock wise and pull the handle to open the trunk and that works fine.

My research shows it has two micro switches in the handle latch assembly which I checked electrical connections and below that assembly I pulled the actual latch off and can see the little motor and gears spin when activated (the whirr noise) but it does not release the latch when pushed close with a screw driver. I lubricated this as suggested but it did not solve the problem.

Has anyone else repaired this on their own and found a solution with these symptoms?

Would replacing the micro switches in the upper latch handle assembly fix this or the fact that the motor and gears spin mean they are activating the release mechanism and something is broke down inside where the manual cable can be seen to release the latch?

Any help would be gratefully appreciated. Thank you...

pcy

I believe there is a plastic 'arm' that attaches the lock actuator to the release mechanism. Due to wear and age, that arm breaks. That may be the cause of your problem.

I have seen few threads on this topic on W163 forum. Please search on W163.

LADYBNZ

Thanks for the info. Would this plastic arm be located in the lower latch assembly with the motor and gears assembly?

I searched W163 forums and not any details as how to repair. Seems a lot of people have had this problem of hearing the motor run but not releasing the trunk latch but nobody says how they fixed it.

Anyone else with technical details or part numbers for repair? Thank you...

Glyn M Ruck

Vomit

Hey LadyBenz:

Did you ever find a solution for this problem? I have the same problem on my 2002 C32.

Thx

LADYBNZ

Hi, Thanks for asking but , NO... My trunk is still broken and a real pain not having it easily available. It does open with a key, but rain, snow and an arm load of packages makes it very inconvienent to use that way.

I believe the plastic arm is broken in the assembly, part #10 in the diagram Glyn Ruck posted, (Thanks!).

It has the little motor and gears that spin when activated, but the arm doesn't disengage the latch.

It appears to be a whole assembly and I would like to locate one to purchase and install my self. My dealer is a long ways away and wondering if it can be bought on line, or at a wreckiing yard?

Does anyone have a Part Number for the assembly #10 in the diagram or a source? Has anyone else had the same problem and did this fix it?

Thanks for any info, and a Happy New Year to you all!

ps... Got a new 3 bar black and chrome grill for Christmas! very nice!

LADYBNZ

A quick search on-line found the part I am looking for:

http://www.partswebsite.com/benzpart...60&catid=30200

Part number 16 on the diagram, "trunk latch", $77.60

Any experience with this vendor? Price looks ok to me... Thanks!

LADYBNZ

Yea! My research and patience paid off with the help of the forums I fixed the broken trunk latch on my C240 Benz.

Here is some additional information for those with the same problem as previously described above. The part I replaced was a latch assembly with a short cable and electrical connection but is called a "Lock" on the packing slip.

P/N 171-750-00-85 Lock, Sale price was $58.40

Also P/N 037-545-65-28 Plug, $2.72 is needed to complete the repair.

The part has been updated from a 3 pin electrical connector to a 4 pin connector and is why the new 4 pin connector is needed.

The small connector has tiny numbers on them 1-4 and need to be wired accordingly. On the new 4 pin connector #1 pin is not used.

The plastic connector has a lock that has to be lifted for easy removal of the wires. Once removed each wire has a lock that has to be pushed with a small screwdriver to unlock each wire. To avoid mistakes remove one wire at the time and connect it to the new connector.

1-not used
2-brown/yellow
3-brown
4-white

I tested the unit before installing trim pieces and all trunk release buttons worked great, door, smart key, and green trunk release buttons.

To attach the upper cable simply pry up the plastic covering over the lock cylinder assembly and pop out the ball and cable through the slot.

When reinstalling trunk liner be sure to press the large part of the plastic rivets all the way flush to seat them before pushing the center rivet into them.

I purchased my parts on line through:

Mercedes-Benz of Monterey, Stah Motor Company.

Ordered on a Sunday and received Tuesday. Fast service and a great price too. Same part was over $100.00 elsewhere and I was billed less than posted on thier website. I hope this helps some others, and thanks for all the help I received.

Glyn M Ruck

Pleased it's fixed!

pcy

Thanks for updating the post with part numbers and price of the parts.


If you had taken the car to MB dealer for fixing that lock, I bet you would've had to spend a small fortune. Persistence paid off. Excellent.

imthebigfish

All is well but I cant remove the plastic handle on the trunk, you unscrew it and it wont come out? seems you need to get something to push in on the inside to pull the handle off? anyone know how or what tool they used? Thanks, biggish. Oh and the part number on it is #24 I think if I can get that off with out braking it im sure i'll be able to do it my self. Just need to know what tool to use to release it from the trunk.

C230 Sport Coup

Ladybenz, I often order parts online, but typically the best prices are
from dealers on the east coast, or parts dot com.
Stahl is fairly close to me, how was their pricing?

c240latchkeykid

If you move the cover to the right, slightly and then gently use a flat head screw driver into the small (1/2 inch) opening and apply a very light push, while pulling the cover away, it should come right off. "Gentley" is the magic word here ... I wrestled with it for about 15 minutes trying to muscle my way around it and yank it out, and nothing ... so then I tried the light touch and it worked. Good luck :-)

c240latchkeykid

LadyBnz, how did you work the cable pin to catch on to the latch tongue and grove thing? I've replaced the lock but still can't get the latch tongue and grove to work properly ... I am also missing the 4-pin adapter. I got my latch from the local dealership but of course they didn't tell me anything about the 3 to 4-pin issue. Is that extra little adapter required? Could it be why the latch isn't working? When I use the manual key and turn in counter-clockwise, and hold it, the manual latch catches (or pulls) the cable and pops the latch.

Kenmahi

The posted procedures are great except for attaching the new unit release cable. 'Simply pry up the cover and remove the cable through the slot' failed for me. I could have broken the cable loose and then had a trunk closed forever. Anybody have more detail on this aspect of the trunk fix protocol? If removing the upper, lock cylinder unit is an option, how might I do that? Are the bolts behind the license plate light sockets?

The trunk works like an American car now, only opens with the key. I'd like that Euro convenience back. Thanks.

GINO-ESC

did you recently do any mods? when I added the rear trunk lip the hydralics were not strong enough to lift the lid with the extra weight. It will pop the lock open, but you have to lift it manually. It will stay up once you do that.

samaritrey

You can adjust the springs on the w203 to fix that issue.

WhiteMerc

Can anyone explain how they removed the upper cable/ball from the cylinder lock? I've been prying back at every angle on the plastic part and can't figure out how to get the cable out. HELP.

etty

Thank you for your post! It helped me to fix same problem with my Benz. All parts were $111 (including shipping), 30 minutes of my time and BAM! Magic... my trunk works perfectly.

Few problems I was facing:

1. Make sure you have DorX screwdriver with different sizes. Got one from HD for $9.99
2. To remove "release cable" of the cylinder lock, use flat scredriver to open the plastic box.

firstdown80

I had the same problem. Took it to a shop and they told me that both the latch & the lock (A1717500085) had to be changed. They gave me a quote for $350-380, parts & labor.

I don't think I needed to replace the latch, so I just bought the lock (A1717500085), and decided to fix this myself and bought my parts online.

Hope these pictures help. Note: After I reconnected all the wires, it still did not work. So, I guessed something had to be reset, started the car, turned it off, and tested the with the remote and the switch inside the car, both worked.

hanson7

THANK YOU VERY MUCH ALAN FOR SUCH A DETAILED INSTRUCTIONS.

Kenny live

hi, all very useful and precise info. Same part no,s in use in Ireland.. lock costs 65.66 + vat and plug costs 3.66 +vat

firstdown80

@ hanson7 & Kenny Live, thanks. I get parts from AutohausAZ for all my repairs. Next I've got to figure out the squeaks coming when i turn my steering. On to the next project.

C240DRVR

I experienced the same problem where the trunk release on my 2002 C240 Sedan recently quit working with the key fob, driver's door switch, and emergency release in the trunk.

It also made the classic "whirrr" sound (only intermittently, which I thought strange) but did not release the latch. I too was able to open the trunk with the manual key. After I opened the trunk with the key, I found a small white plastic part on the carpet (obviously broken off from something). The part is cylindrical, about ¼ of an inch tall, and about 3/16 of an inch in diameter, with a small hole through the entire cylinder, the diameter of which looks to be the size that would allow the wire portion of the mechanical unit release cable to slide through it.


Since the symptoms were identical, I thought replacing the Lock and the Plug as posted by LADYBNZ would resolve the problem, so I initially called my local Mercedes dealer and was quoted a price of $149.65 for the Lock plus $300 to install it. After hearing those prices, I didn't bother to get a price for the plug. I decided to look into ordering the parts online and installing them myself. I shopped around a bit, and also ended up ordering from Stahl Motor Company in Monterey, CA. I ordered from their web site, www.benzpartswholesale.com after first speaking with them via phone (Phone 1-888-904-5366). They were very helpful. Although the prices have gone up since the post by LADYBNZ, I did manage to save 20% by ordering from their web site. Here is what I paid:

P/N 171-750-00-85 Lock, Online price was $97.60

P/N 037-545-65-28 Plug, Online price was $ 4.00

FedEx shipping charge was $10.16, for a total of $111.76.

I live in Arizona. I ordered the parts in the early afternoon on a Tuesday and they were delivered by about 11:00 A.M Thursday. Less than two days -- pretty good.

I tried installing it myself, and while the detailed instructions posted by firstdown80 were extremely helpful, I just couldn't get the cover off the old part in order to gain access to the mechanical unit release cable. So rather than breaking or messing something up beyond repair, I took it into a shop in Scottsdale. They installed the new part in about a half hour, and only charged me a little over $30 for the installation. Unfortunately, it didn't resolve the problem. I was still only able to open the trunk with the manual key, but it no longer made the classic "whirrr" sound (in retrospect, that should have been a huge red flag for me).

Since the other end of the mechanical unit release cable connected to another electro-mechanical part (the "Handle"), I figured that part must be the problem, so I also ordered that part from Stahl Motor Company (Part #203-750-08-93, cost $72.00 plus $9.30 Fedex shipping cost). Again, the part was received in two days. It looked as if it was going to be considerably more difficult to install than the lock, so I just brought it to the same shop for installation. I was right – the part performed the same function, but it mounted differently than the original part (they had to drill a couple of holes behind the license plate to mount it). Total charge for installing the handle was a little over $105. Again, unfortunately, it still didn't resolve the problem. I was still only able to open the trunk with the manual key, and it still no longer made the classic "whirrr" sound.

The Manager at the shop thought it might be a problem with some electronic computerized component, but couldn't be sure. He thought I might want to go to a Mercedes dealer and pay them to diagnose it for me. I considered that, but after already having spent more than $330 to replace two parts, at least one of which may or may not have needed to be replaced, I also considered just living with opening the trunk manually.

The next day I thought about it more, and decided that the loss of the classic "whirrr" sound may have been an indication of a simple electrical problem, such as a blown fuse. I checked the fuses associated with that circuit, and none of them were blown. Then it dawned on me that, given that the fuses were O.K., and assuming the newly installed parts were O.K., the next most logical simple electrical problem that could have resulted in the loss of the classic" whirrr" sound was the lack of power being applied to the lock. What could have caused that? THE PLUG!!!! I checked the wiring of the plug, and sure enough, the new plug had been wired incorrectly. I rewired it according to the instructions provided by LADYBNZ (thank you so much, LADYBNZ!), and everything worked perfectly.

In fairness to the shop in Scottsdale, the numbers (1 thru 4) on the plug were so small, they could barely be seen, but the plug was definitely wired incorrectly. I suppose I could have given them LADYBNZ's instructions on how to wire the plug, but I know shops such as that subscribe to a service that gives them access to detailed instructions, so I didn't bother. It may not have mattered, but then again, it may have saved me the nearly $200 I spent on the Handle and its installation.

I called the shop Manager and told him what I found and how I fixed it for their future reference, so maybe some other M-B owner would be spared the additional cost and the aggravation which I experienced. They apologized and said they would let the mechanic know. Since I ended up with two new parts (the Lock and the Handle) and still saved about $130 - $140 vs. buying just the Lock and having it installed at the M-B dealer, I didn't push the shop for any direct compensation/credit for their error at this time. I did, however, indicate that I may be bringing the car back to them for some work on the cooling system, and implied that they could cut me some slack on the cost at that time.

ez53436

Hi all, i know i'm reviving an old thread here but I have this same problem on my C32 and there seem to two options on all the parts websites for the trunk latch/lock.

One version is "w/ keyless" and the other is not. One looks like it has a shorter cable too. Anyone know what exactly that means?

Also, I se that you guys had to wire the new plugs in a specific way, does that mean you soldered them?

Thanks in advance!