Hi everyone,

I have a 1991 Firebird that I'm working on and one of the issues it came with was the headlights not raising up. They turn on just fine, but do not flip up. The previous owner worked on the issue for a while and replaced the headlight motors and the headlight switch, but no improvement. I do a decent bit of 12v work so I figured it couldn't be too hard to fix, but that's what I always think.

I have confirmed that both motors raise the lights just fine if you just put 12v to the motor directly. I first read about the headlight module issues, so I took it off and soldered the large pins on each side to make sure they weren't having an issue, no change. Today I went under the dash and checked the headlight motor fuses that are on the separate block with the horn relay and buzzer. Both were intact and they tested well for continuity across both pins. My door open buzzer is shot so I removed it in case that's relevant. I confirmed that when the headlights are turned on, both fuse sockets get + 12v signal, Followed around to the engine bay and took off the 4 pin and 5 pin connectors on the headlight relay module.

First I tested continuity on all of the wires that run from the headlight module to the motors, all tested okay. Then tested thr 5 pin connector coming from the car into the module, I have +12v on the yellow wire and both orange wires going to that connector. The brown wire and black wire both tested as grounds and had continuity when tested against a piece of the unibody.

The 4 pin output connector that goes to the motors has a grey wire and a green wire for each side of the engine bay. If I test a gray and a green wire for 12v, I get nothing.on them. But if I ground the multimeter on the unibody and test any of the pins, all 4 of them are producing +12v signal, so both the gray and the green wires are putting out +12v.

At that point my knowledge tapped out, I'm not sure if that's by design or an indication of my issue. I took the module apart again and didn't see any obvious failure points. I tested the gray/green wires for continuity and they're not connected so it doesn't seem to be a short in the headlight module. If anyone has any ideas on what I might check next, any help is most appreciated.

Thank you!

-Tony

 

There are a few pages in the service manual that cover troubleshooting the pop-up headlights. If you had started with those charts and guides you would likely have already found the cause of your problem. I'd recommend you beg, borrow, or steal a copy of the GM service manual, and follow it's instructions.

Beyond that, if it's not the pellets in the motors, it's usually a bad control module. The module is not supposed to be serviceable. Back in the day, GM just wanted you to spend $140 on a new one. They can be opened, and some people have rebuilt them, but really it's just easier to start collecting them from the junkyard. Fieros, Corvettes, Sunbirds, think there's a Buick or two... There are two versions of the module, they supposedly don't interchange, but then I've also heard they do.

In a moment of true desperation, you could turn to the Googler to determine which modules should be the same. You might even find the pages scanned from the service manual.

FWIW.

 

If you have +12V power on the yellow and brown wires with the headlight switch turned on , and also +12V at all times on the orange wires from the two 15A circuit breakers (and of course a good ground on the black) , and you say you've made sure both headlight motors are good , the logical endgame is that your headlight module is bad ....