Ok all I swear my burban has a gremlin........my brake lights will work sometimes and then other times wont. Now that being said I have replaced the brake light switch and the circut boards, the only lights that DONT work are the main brake lights.....the 3rd brake light has always worked even if the others dont. So as a temp fix I ran a wire from the 3rd brake light switch to the other lights but I really need to figure out whats going on. ANY IDEAS??????

 

Could your trailer harness be periodically grounding out? I have seen some real butcher jobs on trailer harness installs. Just a thought.

 

Its possible i guess but I installed the 2 harnesses ( flat 4 and round 6) so I know the job was done right. The way it seems is that once the truck warms up they tend to work. Its very strange. And climbing under the burban today isnt going to happen, we got 12" of snow last night. So I have them working for the moment just no turn signals cause of the constant power when on the brake.......maybe a bad multi function switch???? Im not sure if the 3rd brake light runs through the switch or if it is a direct connection from the brake light switch.....any other ideas?

 

bump.....any more Ideas???????