Recently my door lock on the drivers side of my C240 has been going crazy.
If I try and lock the car with the key switch it will go up and down uncontrollablly. This problem just started not to long ago and I thought I would go away or fix itself, but now its just driving me crazy!!!

Any suggestions on how to fix this...or has anyone had a similar problem? Any HELP would be apprieciated....Thanks!!!

 

I had the same thing with the door lock (02 C240) happen to me a few months back. Hit the remote to lock or unlock the doors, and the door lock would bounce up and down 3 or 4 times. Sometimes it wouldn't lock automatically, would have to use the manual key sometimes.
I ended up purchasing a new auto lock assembly (made by Hella) from the dealer and installed it myself. I asked one of the mechanics how long it would take and how difficult to change. You need to have some mechanical knowledge and it will take somewhere between 2-3 hours (took me a little longer). You also need to drill out some pop rivets to make the job a bit easier. The mechanism is fairly tight to remove and re-install. The pop rivets will have to be replaced when the door latch mechanism is in place. MB will also sell you the pop rivets. I'll have to admit, it was a bit fustrating at times to shoe horn that thing in and line it up. It's done and it works great!
Someone mentioned to pull up the rubber boot that slides over the door pull rod and to put some lube on the rod. You may want to try this out first. Just remove the door panel and you will see the rubber boot. Nothing to lose by trying this first.

 

I had the same thing happen in my C230K. Turned out in my case that the lock assembly had broken. I got it fixed at the dealer, but since it was under warranty it was free.... So I don't know how much it would cost for a C240 out of warranty. (Unless you have a longer warranty than mine - which is a 3 year bla bla bla)

 

Thanks all for the replies...I will try your suggestions and see what works...If not, off to the dealer to get raped with there charges, since the car is not under warranty...but its driving me crazy, so it needs to get fixed. [:@]

 

Why must u go to a dealer if i had that problem i would take it to an Upolstry (sp? i cant spell lol) shop at least the one were i live does power windows and power locks and always an excellent job. They fixed the sunroof on my 560 for only 150 bux labor plus the parts that i suplied. and they also fixed my power window when it went out well the bushing broke but u get the point.

 

another possible reason --

the Cseries is so tightly sealed that sometimes the last door closed with the windows up doesnt close all the way. We have to really close the last door (no matter which one it is) forcefully.

If the door is slightly open,the door locks will intermittentlylock and unlock, driving you crazy.