Need some help with door locking problem. The driver side door will not lock or unlock with the key. All doors have to be locked manually but the key does lock and unlock the passanger side door ONLY. any help will be appreciated.
thanks
Tom

 

Do you have a PSE Pump for the central locking?

 

Yes the pump is located under the rear passanger seat. I took a vacum tester and check the lines, all held pressure except one that runs along the door jam toward the front. I pulled the jam up and trace the line down to the front passanger seat. any idea where it leads to before I take the next step?
Tom

 

If the line leads to the front seat and is gray it is for the orthopedic backrest, but it should go to the thumbwheel on the seat first. If it is clear it would go to a reservoir under dash and is the manifold vacuum assist (when the engine does not produce any)
The lock and unlock function:
The door locks have microswitches when turned to the unlock position it sends a signal to pump under the seat which produces pressure and is sent down the yellow line to doors , trunk and fuel door. When it hits the pressure point internally it shuts off, if it does not in 10 seconds it will also shut off. The reverse is on unlock, the pump also gets a command from the infra red remote module to lock or unlock. It will also run to replenish the orthopedic reseroir (pressure) and the HVAC (vacuum) there is a 60 second timeout on those functions. The drivers door diaphram has an electrical connection to the alarm module.
orange=back up rods
black=lid grip
yellow=locking

 

I turn the key in the passanger door and I got a light when it was turn to lock and when it was turn to open. I did the same with the trunk and got a light when open and to lock, some how the fuel flap locked and I had to go in the trunk and pull the emergency button. Now! when I manually put the door lock down and put the key in the driver door it will not turn to theright but will turn to the left also the light does not come on like it do on the other door. do I need to pull the door panel and look for a loose wire or short out?
Tom

 

The issue that is stated above happened to me, but it seems I have 2 issues. I believe my pump is out since the fuel door lock, central lock button and automatic door locks don't work. The issue described by the poster of the key not working the driver side door is another issue I just resolved on mu 1992 300SE. What had happened is that the door handle mechanism that has a long skinny key that turns the interernals of the door broke off. So by turning the key in the driver side door, nothing happened. I found the long skinny key like piece, adhered it back to the door handle, placed the door handle back in the door, and vola, the key to the driver side door works.

To check this, all you need to do is remove the door handle locking screw on the inside of the door jam and the door handle comes right out.

Hope this helps.