95 S420 central locking question
 

How do I access the central locking pump and how can I identify the line that goes to the driver's door?

Thanks,
Sixto
95 S420
91 300SE
87 300SDL
83 300SD

You will have to remve the left side trunk interior side and front panels. To make it easier first remove the plastic trim piece running from side to side at the trunk latch. The pump is in the front left corner covered in foam rubber. All of the signals from all of the doors and the corresponding vacuum lines all attach to the pump. It is not owner serviceable. There is a microprocesser inside that has to be replaced. The reason that the system can be temporarily fixed by removing and then reinserting fuse #9 in the trunk is that you are re booting the microprocessor. This is only a temporary fix. It may work for days then will eventually work for hours then only minutes. Several advertisers in "The Star" have an exchange service for this item. Call George Murphy or Beckmann Technologies for a troublefree rebuilt unit.

Double check which mechanism
 

I believe the information in this post is correct. But I think it is for the pump that powers the door and trunk assist closing mechanism, not the central locking system. I belieive that pump is under the rear seat. Might be worth double checking before removing a lot of stuff.

The previous posts can be misleading, there are two pumps on the car, the closing assist (draw-in) which is located on the top of the drivers side rear wheel and has red hoses coming from it. The lock/unlock is under the passenger side rear seat, the lock /unlock elements in the doors trunk and fuel door all share the same hose and are a yellowish hose coming from the pump. If only one lock does not operate it is typically a element associated to that door, if "all" dont work it is probably a bad pump. There is a tool called a MiteyVac that allows you to draw a vacuum on a hose and see if it holds via guage. If it does show a leak it is a function of tracing it to either a hose connection or element. There are "ts" and door jamb connections involved. It is pressure to unlock, vacuum to lock.