Strange Electrical - 87 Ram 150

[simpelli]

Greetings,

I'm in the process of restoring an 87 Ram 150 LE short box. (First project like this) So far, mechanical and body work has gone well, but I ran into a strange problem with the brake lights.

They come on normally with the headlights off. When headlights are on, running lights appear as they should, but when I hit the brakes, the tail lights go out instead of getting brighter. I've probed the harness at the end of the run (just before the tail light wiring assembly) and it operates correctly with the tail light assembly unplugged. Also, if one or the other tail assembly is disconnected (left or right) the opposite one works correctly, but not when both are plugged in.

No broken wires on either assembly.

Any thoughts?

Thanks

[crazy cajun]

has to be grounding out somewere when brakes are applied

[simpelli]

Yeah, thought of that.

How would you trace that kind of thing? Start at the switch? What do I look for?

[crazy cajun]

i would start in the back at the lights look for a wire that has a cut or been smashed and is missing some of the coating its like finding a needle in a haystack.

[sleepygene62]

check the tailight assembly it self for ground, if you have the ground end of the test light on the taillight socket you should get ground, if not run a wire from the frame to the socket or track down the factory ground in the harness, a bad ground will do crazy things sometimes.