I have gone through the archives and found a lot of info on this subject, and I have put much of it to use already. Here is where I'm at:

The trunk close assist is not functioning. All other vacuum related convenience accessories are working fine (door close assist, reverse rods, retracting trunk handle). When I close the trunk softly nothing engages- I need to be somewhat forceful for it to latch. When the latch does catch, the trunk lid sucks down about 1/4", then after about 2 seconds there is a slight hiss and the lid goes back up 1/4".

So far I have troubleshooted the following:

The bottom latch was loose as many others on this board have discussed (in fact, one of the bolts had completely come off). I tightened it and there is no longer as much of a gap between the body of the car and trunk lid when shut. As far as the close assist, I have pulled the #9 fuse and no change. Pg 118 of the owner's manual explains manual closing of trunk lid- "push sliding switch to left, press eye of latch in, push sliding switch to right, close trunk lid." Moving the manual sliding switch to either position doesn't change anything. And I can't seem to be able to push the eye of the latch in. There is a little play in the latch and when I trigger the bottom latch to simulate the trunk closing, the handle retracts, the eye of the upper latch moves up about 1/4", and then after the hiss moves back down.

What should I look for next? Is the latch itself perhaps bad? I am relatively new to this board but I have already found a lot of helpful information - thanks!

Hi There is a TBS for the closing assist on your trunk,most were done at the dealer in the 90S.The # is group 72 TB 72/8 and should come as a kit from the dealer it includes a extended striker ect alot of little parts and time if you send me your fax # I will be glad to send you a copy.joeym

I've had a similar problem on my w140. I discovered the lower latch was recessed to low for the catch to successfully engage. And after slamming the trunk lid to help the latch meet the stiker it would eventually slip agian. After moving the latch up a few centimeters, things were back to normal again.

I've attached the MB procedure for adjusting the latch.

The last photo Trunk3.gif #7 was the fix for me.

Attached Thumbnails

     

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Russell McMahon
Tulsa, OK
2001 CLK 320
1992 400se
1993 400e
2000 320ML

Thanks for the tips! joeym, I sent you a private message with my fax number. rsmcmahon, I assumed that moving the latch down would help minimize the gap between the trunk lid and the body of the car, but perhaps you're correct and it's too far down and needs to come up a little so the power assist can engage. Of course now I'm out of town for a few days so it will have to wait until I return to try it.

One more question- the lever I mentioned in my original post for manual closing of the trunk lid ("push sliding switch to left, press eye of latch in, push sliding switch to right, close trunk lid") - what should that do? Mine doesn't seem to do anything when moving the lever to back and forth...and when you press the eye latch in, what should happen? Again, mine just slides a little, but based on the owner's manual description, it sounds like it should lock in or 'click' or something. Thanks!

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1994 S500 coupe
2005 ML500
2007 E350
(en route) 2005 CL500