92 Lesabre strange problem fix FYI

[spinne1]

I just had a difficult weekend diagnosing a nasty electrical problem. I am posting in case anyone else ever has the same symptoms. If so, perhaps it will be the same problem.

My symptoms were:
1. When the car was running the interior dash lights were on without having the head or park lights on.
2. The car would want to completely quit when applying the brake pedal or either turn signal. (an electrical collapse--the car would stall because of it)
3. When the car was off completely and I hit the park or head light switch, the interior dash lights would all come on and the radio would power up including the automatic antenna and the speakers would let out a horrible pulsing.
4. When the radio was disconnected, the car behaved normal in that the interior lights would not come on and also the car would not stall or give trouble when using the brake or turn signals.

I found that the affected fuses were fuse 21 and fuse 24. This led me to investigate the Light Control Module. After extensive testing, it was found to be good. I then tested the interior light dimmer, which also tested good.

The problem turned out to be the Remote Dimmer Module. To test it I had to halfway dismantle my dash, including the large colored piece that forms the bottom half of the dash (I didn't remove it from the car but simply pulled it downward out of the way). The Remote Dimmer Module is attached to a metal u-shaped piece directly under the steering wheel on the right side and has gray, green, and black wires running to it. It is attached to the metal u-shaped piece with two 7mm bolts, which also have the star-shaped hole in them for using a star-type screwdriver. This device is supposed to send out reduced voltage when the sliding dash dimmer is moved down and vice versa, but it was sending out full voltage all the time.

EDIT: The Remote Dimmer Module did not fix the problem, though it did test bad. Also, the interior lights dimmer on the dash went bad during this process, requiring me to get one from a boneyard. I finally tracked down the real cause of the problem to the radio itself. It was passing voltage back down the wire to the Remote Dimmer Module whenever the car was in accessory or run causing the dash lights to come on. When I hooked up another radio I bought at the boneyard, the problem went away and all is back to normal.