central locks - lotsa fun...
I have spent several hours recently trying to isolate an annoying problem with my wife's 1992 735i central locking system. The Bentley manual provides a unique chapter just for this system, so what does that tell you ?
The site below is a terrific resource to understand the system and learn about the most probable failure modes. While it is devoted to the E32 7 series, virtually all of the information pertains to the E34 as well.
After throwing a few parts at the E32 without success, I was forced to break out wiring diagrams and a volt/ohm meter. Finally found my problem to be a broken wire (somewhere inside the door) to the driver's door micro-switch.
have fun !
let us know what you learn,