1998 GMC suburban 4×4 brake fuse keeps blowing. I installed a new 7 prong trailer plug. I know everything is hooked up properly. Can't find any cracked wires. I unhooked everything in the new plug. Still pops fuse as soon as I hit the brake pedal. Could the brake switch be the problem?

 

could be a chaffed wire that goes from the brake switch to the tail light housing. that is if you havnt check them already, but you also might have a high mount stop light on the back of the cab

 

Somehow the ground wire on my wire harness to the taillight harness has become energized and pops the fuse when I hit the brakes. I finally disconnected the ground wire and all is good. One of these days I'm gonna run across the cause..........

The wire in question is grounded to the frame in the rear of the truck. It's the first wire out of the loom before the T-connector.