Headlight Up and Down

[z00618]

I am working on my daughter's 1994 Firebird, which already has the brass gear modifications to the headlight motors (what a great mod it is, too!). They have worked great for about a year, but the new problem is this: When turning the headlights off, the passenger side light lowers and then raises back up. The driver side works fine. There's no strange noises, just odd operation.

I have read about relays that control operation, but since the lights consistently do the same thing every time, it may not be relays. I suspect the headlight controller module (which I have located on the driver's side inner fender under the engine air intake nozzle). I don't want to buy another one ($$$) until I'm sure this is the problem. Any ideas??

[FormulaLT1]

test the voltage to the harness when its not fuctioning correctly. if the voltage is correct it may be some internal electrical problem with the motor itself. Good luck and keep us posted.
John

[z00618]

I sampled the voltage at each headlight motor and they were identical (though trying to see it with a digital meter is tough...analog would have been easier, I think). So, since the voltage to each motor was the same, I began to wonder how one motor would respond differently to the same voltage. Upon further examination, I found that the fiberglass panel beside the motor has a small extrusion (about 5/8" in diameter, approx 1" in length) that acts as a "stop" for the elevator linkage. On my problem light it had broken off and was lying in the bottom of the headlight enclosure. Fortunately, this stop is molded with a 1/4" hole through the center, so I ran a screw through it and fastened it back to the fiberglass panel it fell off of. Works great now.

Apparently, if the motor linkage doesn't hit this stop, the headlight control logic leaves the light to a "safe" position (up) when its turned off.

Your idea about comparing the motor voltages got me heading in the right direction. Thanks!

[FormulaLT1]

No problem, Glad you figured it out.
John