Lighting Issue

blue72super

Registered User
This one has got me. This started about two weeks ago.
When I pull the headlight switch out to the park position, I get no lights. When I pull it all the way out to the headlight position, I get all the lights. If I turn on the high beams, all the parking lights and the dash lights go out. I have tried a new headlight switch, the dimmer relay under the dash above the gas pedal, and a turn signal/dimmer/wiper switch. None of which corrected the problem. The driving lights work with the headlights on and go out with the high beams, which is how they are suppose to.
Is there something else in the system that I am overlooking? Does anyone have a copy of a wiring diagram fro a 1990 they could email me?
Does anyone have any other suggestions to check?
Thanks,
Clark
 
I had the same exact problem with my 92 and it was the head light switch? I would double check and make sure didn't get a bad switch.
 
Alright, I tried another new headlight switch. I now have the new headlight, relay, and multifunction switch installed and I still have the same problem.
No lights in park position, all lights in on position, and I loose dash and running lights with high beams on.
Clark
 
Did you use the correct multifunction switch which depends on whether your car has the auto-headlights dimmer option?
 
Yes, I used the one with the auto-dimmers.
Is there another relay in the system that could be causing this?
Where can I get a good wiring diagram for a 1990 SC?
Clark
 
The dual coil relay is needed/used only when the autolamp control thumbwheel is turned on. All the lights should work when turned on manually even if the dual coil relay is unplugged.
Have you verified that the outer headlights come on when you turn on the low beams? The inner headlights are the high beams.
There is no other relay in a stock unmodified lighting system.
 
No aftermarket alarm. Low beams do come on, but they and the parking lights go out when I go to high beam.
In the absence of a wiring diagram I disected the old headlight switch to determine what terminals were for what. I am getting voltage at the main headlight (yellow) terminal, but am not getting anything at the parking lights (yellow/black) terminal. The parking light fuse is good.
Does anyone have a clue where the wire goes in between the fuse and the headlight switch?
Clark
 
This might be a long shot, but I had a problem with my headlights, and tracking it down was just luck. At the front of the car slightly off center on the passenger side was a little multiple connector for grounding more than one ground on the car. It is about 1-1/2" x 1-1/2" x 1/4" black square thing bolted to the car with a plug for about 6 connectors on the bottom of it. The connector that plugs in at the bottom had worked its way loose over the years. I took the connector off, cleaned it up, snapped it back in place and the problem with my headlights went away. Something to check.:)
 
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