Automatic Door Lock/Unlock 0n '92 300E
 

:mad: The door lock/unlock function from my driver's side door is not working to lock/unlock all the other locks on my 1992 300E. The passenger-side door and trunck lock do function properly to lock/unlock all the other locks, so the system that locks/unlocks doors universally is working. Just not when I turn the key on the driver's side door.

Is there an easy fix for this? I'm supposing it's got something to do with the driver's side door lock mechanism itself. Somehow, the signal from that lock isn't getting to the mechanism under the rear seat that controls the universal system.... electronic or mechanical issue?

Any help would be much appreciated. Thanks!!

Your car probably has a vacuum leak in the drivers
 

door, the passenger and trunk locks will work with the drivers door but also will lock and unlock independent of the central locking vacuum driven system. These systems are complicated, but I would get a vacuum pump, you can pick up a hand pump in any auto part store and get a dieagram of the vacuum system for the doors and start testing for leaks. The trunk lock won't lock or unlock with the drivers door, but indenpently with will work with the key, the pasenger door works with the central locking and independently. The sytem is designed this way. It is probably the vacuum actuator in the drivers door that is bad.

Cake fix!
 

There is a switch on the side of the lock cylinder that controls the pump. No leaks, forget that, the old 107/123 design was as Al mentioned above. Not the case for 124/201s. The vacuum actuator in the door is independent of the locking activation, other wise the trunk, other doors AND the fuel door lock wouldn't work either. Also, you wouldn't have activation from the right door and trunk.

The lock assembly comes out from the outside, a 5 mm allen wrench through the small opening in the edge of the door. The gray bezel comes with it, as does the door handle. There is a second rubber plug below the small hole for the electrical connection. Here's the rub, I THINK you have to get the whole lock and switch from the dealer, and yes the new cylinder keyed to your car comes with it. (It's a security issue with MB, they control all the locks and keys in Baltimore, and the only way you can get a replacement cylinder is keyed to your serial number/VIN.) You'll need the serial number as well. This switch controls the alarm and all window/roof closed feature as well. I may be really wrong about the switch not being available by itself. Check for a part number on the white plastic part of the switch.

So, plan 2.

The switch comes off the cylinder and is interchangeable with the right side. It snap fits to the side. If you can cooers the salvage yard to pull one from a damaged door, your in for 10 bucks, otherwise, i think they are about $135 new. If your dealership is flexible, they might let you scavenge one from an old, used or defective unit. this is a 20 minute job even if you make a mess. Your near by independent MB shop may have one in their 1000 year drawer.

plan 3,

Swap them round a bit with the right for the left, till least you can find a used switch.

Good Luck!
MG