1992 240 4 door sedan

The right rear window won't roll up. The window switch on the rear door won't work and neither will the switch on the driver's door. All other windows are OK. It will roll down but it stays down. What could be wrong - motor or is there a brain control module somewhere? Could it something mechanical in the door?

Please advise. Thanks.

If you try the switch-swap and that doesn't work then one tool that I acquired that's proved invaluable and helps in this situation is to get a portable 12V power supply. Using alligator clip test leads, plug it directly into the window motor wiring harness after you unplug it from the switch. You can roll the window up and down this way and check the motor. I haven't found a bad motor yet but I used it once when my battery was dead and the window was left down to roll it up. Good Luck!

Great advice!

Thanks. I had that in mind - swapping switches first then opening up the door.

Try this as a test for faulty switches. Remove or loosen the driver's armrest enough to slide out the windows switches assembly. Swap a switch from a working window with the faulty switch. Operate both switches. If the problem shifts to the other window and the right rear works, then the issue is indeed a faulty switch and the motor is fine as is the window's mechanical mechanism behind the door panel.

The internals of a window switch can get gummed up over time. Careful disassembly followed by cleaning, even cleaning the electrical contacts should restore the switch function.

If the window switch function isn't restored with cleaning, I'd consider removing the right rear door panel followed with an inspection of mechanical moving parts and motor function.

Mike

I have had this problem off and on over the years. In most cases, it was the switch in the driver's door that was causing the problems. I was always able to fix it by "cycling" the switch back and forth until the window started working again. Sometimes it took a few dozen cycles to get it working again. This cleans the contacts in the switch restoring the connectivity. As suggested previously, before you tear into the affected door, try swapping the dirver's switche first with known good one. Pretty sure that when the driver's door switch gets balky, it also cuts the power to the individual door it serves.
Since the window travels in one direction, this pretty much rules out the motor as the problem.