Hi Folks,
Thought I'd report a success story as it may help anyone with similar symptoms. I have a Citroen XM 2.1 TD, that had door locks that would bounce back to unlock, whether operated from the plip, the key, or sitting inside the car. Sometimes the car would lock, but would unlock while I was walking away from it.
I wanted to find the central locking controller: and from previous posts thought this seemed likely to be in the passenger door, so took this apart. However, I can report the central locking controller for my 93 Xm is probably in the Drivers door, but I still don't know for sure. I just know it isn't in my passenger door.
Anyway, the problem seemed to be that a door switch was sticking in one position. I can tell you there is poor access to the switches and connections even with the doors apart. However, the two blue wires coming from the lock control the direction of solonoid operation, and are switched to ground when they operate.
I stuck a pin through the insulation into one of the blue wires to get contact, and measured with a meter resistance to ground. One of them was shorted to ground the whole time, the other went to ground when the locks were pushed down, but went open circuit a moment later as the grounded signal switched the controller to open again.
So I cut the wire that was permanently grounded. This means the central locking works again from the plip and the drivers door. Lock still works on the passenger door, but unlock on the passenger door now has no effect on the central locking of the others.
Hope this helps someone. [:)][:)]
cheers
Russell