THis is actually for my 92 740, but as it's apparently the same as my 93 940 and the 91 940 I'm using as a test bed I'll post it here.
The central locking does not work. No other door locks worked with the driver's door when that key was turned. I then replaced the servo in the tailgate and that did work. Then it failed. I replaced it again and it worked fine. Then it failed again. Both times it failed, the key did not work in the tailgate itself either. It was as though the servo was frozen, and the key could not be turned. Opening the hatch from the inside and detaching the rod did allow the key in the hatch to work.
I replaced the relay twice with known good relays, no change.
So I want to swap the master switch in the driver's door. I have Haynes, Chiltons, the FAQ, etc etc. Nothing is the same on the cars I have/am working with as in the books. I have removed every screw in the door except the two latch Torx screws on the end, only because I didn't have that bit with me, but nothing releases the master switch. Has anyone actually removed this switch?