Brakelights

[AdamB]

I have a 1994 GMC Sierra and last night I got pulled over cuz my breaklights werent working so when I got home I checked all the wiring to the break lights and found a wire broke, so i reconnected it and they work fine when my headlights are off, the thing is when I turn my headlights on they dont work at all, I checked all the wires back there and couldnt find anything else broken or loose. Got any ideas on what could be wrong?

[GM-Tech]

Sounds like it might be a ground problem or some sort of feedback from the headlight circuit through the brake light circuit.

 

We have had tons of problems with those plates that hold the bulbs. If you have a test light, go back to the connector, take it off and with the headlights on and someone stepping on the brake pedal, see where you have power at the connector. Should be power at the brown, yellow or green wires (depending on which side) if I recall correctly.

 

If you have an added on trailer harness, those are often a big problem too.