z0lt3c

Hi Guys- I picked up a 2009 CLK350 project today at auction. It has 80K miles and the AMG, Sport and Premium-1 packages. Hoping this forum can help me progress on getting it back into tip top shape.

My first issue is that my trunk won't open when using the driver door button, key fob or trunk handle. After alot of trial and error, I eventually figured out that if I first manually unlock the trunk latch using the key, I can then press the door button or key fob and the trunk latch will release opening the trunk (but not the trunk handle). Can anybody point me in the right direction based on experience? I am suspecting an issue with the trunk latch mechanism but I am somewhat perplexed why the key and trunk handle don't work. Is the trunk handle soft-touch or is it supposed to mechanically move like a door handle when operated?

I will post some pictures as soon as I'm done stripping all the aftermarket cosmetic parts the previous owner bolted on.

Thanks,
Z

Rudeney

The trunk handle is both an electrical switch and a mechanical lever. Normally, the mechanical linkage between the handle and latch is disconnected. Inserting the blade key and turning it clockwise connects the manual linkage and then when you pull the handle, the trunk opens. Otherwise, pulling the handle just trips a switch that signals the rear SAM to release the latch. If the car is unlocked, it should open.

z0lt3c

I spent some time diagnosing the trunk issue further. I got a replacement trunk lever assembly from ebay to test with.

The issue remains that when you use the key fob, driver door or trunk lever, the trunk does not open. When you insert the key and turn it, all three methods work. In addition, the trunk lever does not return to the normal position by itself, it needs to be pushed back to be used again.

I moved both electrical connections from the old lever assembly to the new one and it had the same problem. Makes me think it's not the assembly. I am suspecting the problem maybe with the actuator as it looks like it's a mechanical cable connection to the lever which is supposed to return the lever to the start position and is not. Further, after playing around with it for a while, eventually it got to a point where it would no longer latch... I am guessing when you hit the door button or key fob it's an electronic release directly to the actuator and the lever mechanical mechanism is not involved at all.

Rudeney

Note that if you turn the mechanical key fully clockwise and then remove it, it locks the trunk so that it can only be opened with the mechanical key. This is the valet lockout feature. You must remove the key when the clot is longitudinal to the car (i.e. pointing forward/backward, to side-to-side) to NOT engage the valet lock.

SD Spazz

Hi,
I am having a similar issue before I start pulling fuses, I wanted to see if i am doing the right thing. I have 2003 C320. I lost the key and had a new one made by a mobile locksmith. He did not rekey the trunk. Manual key does not work, period. No the key fob and the door button do not work. No way in. I do some reading and there are to fuses that work the operate the trunk. One is in the driver's side fuse box.#40, it says "via the trunk lid/FFS(RBA) separation point lid emergency release switch and the rear SAM control unit with fuse and relay module" What does that mean? The second fuse is actually located in the trunk.
Any suggestions?

z0lt3c

Well jeez, seems like I rebuilt the trunk mechanisms for no good reason! Thank you Rudeney for point out the "valet lock" mode. This was my problem all along, when I picked it up from auction it was in valet mode and I just assumed this was the only mode. Following your advise, I left the key in a longitudinal position, closed and trunk and sure enough all the buttons and levers work now.

My advise is to check if the trunk is in valet mode! In this mode, none of the normal releases will work. When I was trying to "break into" my trunk, the best approach I found was to remove one of the rear deck speakers from inside the vehicle, and then using a rod (or very long arms) engage the emergency trunk release, which is a big red button on the inside of the trunk lid. Once you get the trunk open you can remove the trunk lock and either rekey it or replace it with another part that has the proper key. I happen to have a used trunk lock and key available if interested.