1986 300E Door Locks
 

Anyone have any idea why when I lock my car, only the driver's door locks and none of the others. Is there something I can do to fix this problem. Same thing for unlock, it only unlocks the drivers door. The alarm doesn't work either is that due to the same problem?
Thanks for any help!

Check fuse C for starters.
Also... do passenger door and or trunk key lock/unlock the whole system?
And.. pushing down locks manualy inside car is the same?

Door Locks
 

Neither the passenger nor the trunk will lock the doors either.
Thanks for your tip though. I will start by checking the fuses.

Pull up the rear seat and listen near the right side for the vacuum pump to be operational AND creating a vacuum. It is enclosed in foam rubber.

If it is working AND it is creating a vacuum, then you've got a vacuum leak some where else.

Often, if you can get your car to a very quiet place and try operating the locks etc., you can sometimes hear the leak, such as the trunk area.

Tip, try looking first at the vacuum actuator for the gas filler cover lock. These, for some reason, get disconnected or even more commonly, the rubber bellows simply fail over time.

Haasman

I had a similar problemw ith my passenger door, the pump was working, but the passenger door was not triggering the pump when using the key. it would lock when locking fromt he trunk and drivers door.

I pulled the seat, pulled out the pump and traced the wiring and found a break int he wire and repaired it. I also extended the plug wires and made sure they were seated properly in the socket on the pump.

There should be a harness with a white plug with a single white wire coming into it as well this is all part of the system.

You may need to pull the door lock out of the door, there is a wire that is attached to it that is clipped on tot he door lockw ith a plastic clip. that clip can break and cause it to not make contact, which could be related to the problem.

It could just be that your pump is bad, but I would start with checking the wiring, then if that is ok and the pump is getting power, start checking for a vacuum leak. my fuel door lock was leaking, so I simply plugged the vacuum outlet for it at the pump until I can remove that fuel door lock and try to find out what is wrong with it.

Alon