I have a 1994 Chevy Silverado Ext. Cab and my brake lights wont work if my head lights are on but if my headlights are ofd theywork fine any suggestions?
Grounding trouble can cause all kinds of problems, so that would be the first things to check back at the tail light/brake light wiring, then the lamp sockets, make sure the ground lug wiring is good and not burnt, then the IC board in the taillight housings, you will have to test for power and grounds on each contact strip to bulb connection.
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