1996 Chevy Truck brakelights acting strange

GEORGIABOYZR2

MEMBER
1996 CHEVROLET TRUCK
V8
4WD
AUTOMATIC
140,000 MILES

Im having a crazy brakelight problem. With the truck not running, the brakelights/tailights/turns work fine. But, if I turn the ignition on or start the truck up the brakelights will immediately come on, then when you push the brakes they go off. This only happens with the ignition on or running. Thinking it was the circuit boards in the tailights, I replaced them and no change. So I unplugged the harness where the tail section ties into the body harness. I probed the yellow wire (brakelights/turns) with a test light and clipped it to a ground, and I am getting power. So I believe the problem is further up somewhere. Im decently mechanically inclined, but when it comes to the harder stuff, especially electrical, its a bit challenging. Im away from home and in college so any help is appreciated.

2 Replies

GEORGIABOYZR2

MEMBER
3 POSTS

Okay I just traced the wiring all the way up to where the wires go into the big main plug that goes into the firewall. Im still getting power on the yellow wire from the engine side of that plug with the ignition on when I shouldnt be getting any power untill the brakes are pressed, so this means the failure is in the cab somewhere. I know the multi-function switch, hazzard switch and headlight switch are all tied into this circuit. How would I be able to tell which one is cuasing my problem without having to buy all three switches for trail and error replacement?