Help! Electrical stumper
 

OK...I have a problem that has my mechanic and me stumped. So here is hoping that maybe one of you can come up with an answer. Here are the facts...

The car: 1991 420SEL with 227k miles.

What was done: Mechanic changed the driver's door window regulator (regulator only, not the motor).

Symptoms: After the mechanic replaced the driver's door window regulator, the driver's door went "dead." This is what it doesn't do--->>> 1. When I open the driver's door, the interior lights do not go on. 2. When I open the driver's door, the controls for the driver's power seats do not work. 3. When I open the left door (with the headlights on) the lights-on warning buzzer does not go on. These symptoms are isolated to the driver's door only. For example, if i open the front right door, the interior lights go on AND the everything else works fine.

I took the car back to the mechanic. He checked all the fuses and they all work fine. He checked various relays and they all work fine. He checked the door jamb light button on the driver's door and it works fine. He took out the door panel and checked inside the door for loose wiring, pinched wires, etc., but everything is OK.

Prior to this incident EVERYTHING worked fine in my car. The only work done to the car in the recent past was today's replacement of the regulator. So I figure that working on the door had something to do (but what?) with my current problems.

My mechanic worked on the car for nearly two hours, trying to find and isolate the problem, but all to no avauil. After it got late today, he asked me to bring the car back on Monday.

Before I bring it back on Monday, I'd like to hear from any (all) of you regarding this very unsual problem.

Had the same symptoms
 

Had practically the same problem with the very same car check this out:

http://www.peachparts.com/shopforum/tech-help/11341-91-420sel-no-dome-light-when-opening-driver-door.html?highlight=dome+light

Hope it helps

Nolan

Many times when removing the DRIVERS door panel the wires for the entry lamp will touch each other & damage the printed circuit in the warning buzzer. Most of the time that board can be repaired. Good luck.

Thank you all....
 

...my tech re-checked the warning buzzer relay. It is located under/behind the dash. Once replaced, it all works fine. My tech's assistant replace the door panel, after my tech replaced the regulator. While replacing the panel, he shorted the door lights, that caused the problem.

Again, thanks for your help :D