CLK430 Cabriolet trunk will not lock
 

I've seen several other threads where the trunk gets locked and will not open. I have the opposite problem.

It was working fine until last weekend. I popped the trunk successfully to put a package back there and drove a short distance home. Opened it and got the package out - but when closing it doesn't lock. It will latch, but when you lift the trunk it just unlatches.

With the trunk open, I tested using a screwdriver to ensure the latch is closing. Then I apply just slight pressure (as if the trunk is closed an being lifted without being unlocked) and it just opens.

I've gone so far as to completely remove the latch and disconnect it from all connections...it does the same thing.

Did the latch just suddenly crap out for no reason? Adding this to the list of problems with this car...

37 views and no responses. That's a first ... lol!

I'm going to mess with it a little more, and if I can't get it working I guess I'll have to replace it.

Maybe it's not the actual latch on the trunk that has the issue, check the latch where it connects to the car. It may need to be adjusted.

In addition to previous suggestion, the trunk emergency release lever may be broken. Try this with the windows open and the car running: reach in and lock the doors. Now check to see (1) if the trunk can still be opened by just pulling up and (2) if the fuel filler door is unlocked. If the answers are ‘Yes’ and ‘Yes’, then it sounds like the release lever.

As far as I can tell, it's just a bar. When the latch engages it, the bar forces the latch mechanism to rotate into the closed position. If I simulate this using a thin screwdriver while the trunk is open, it will close but spring right back open with the slightest pressure.

It's similar to what the car door latches would do if the handle was stuck open.

Following this logic is what caused me to remove it entirely and test it.

This sounds like an easy test. I'll try it later this evening. However, I can tell you that I can lock the doors successfully with the remote, but the lights will not flash (and yes, the trunk can still be opened). I haven't checked the gas filler door in this situation.

Is the release lever you refer to easily accessible within the trunk? I have most of the interior of the trunk disassembled as I attempted to address my convertible top issues.

It's the circular green light on the inside of the trunk lid. If someone were locked in the trunk and they pressed that green illuminated button, the trunk would unlock and could be pushed open. The trunk will not unlock if the button is pressed while the car is in motion. That button also unlocks the fuel filler door.

Ah crap...that hasn't been installed in the car in months. As I mentioned, most of the trunk interior was removed during prior troubleshooting of the convertible top and I never got around to re-installing it.

So over the weekend I pulled out the entire keylock assembly and separated the lock cylinder from the latch.

Down inside the latch, I found this:

http://i619.photobucket.com/albums/t...ps05d3a98d.jpg

It looks like a rivet used inside the latch must have snapped off. :(

Problem solved:

So I wound up ordering a used replacement latch for a CLK430 from eBay. Once I got it, I realized that it was wrong - it did not have the electronic switch for popping the trunk. :(

Soooo... I completely disassembled my latch (even removing it from the plastic clamshell). I found the other part of the rivet in there, and try as I might I could not determine where it came from.

I completely cleaned the metal surfaces with brake cleaner and blasted it out with air. The little locking cam that retains the latch when closed had been gummed up. After cleaning, it worked MUCH better. It seems the lubricant used in the latch collected a lot of junk. I applied a light amount of lubricant just to keep it moving smoothly.

So it's working! I still have no clue where that rivet came from since there is nothing in the trunk lid that even looks similar. Crossing my fingers that it stays that way.