Troubleshooting Brake Controller Installation on 2002 GMC Sierra Truck

Question:

blue wire to trailer brake not get any power ,I have found the wire next to the fuse box under hood. blue wire .power up blue wire to rear plug it lights up . no power coming from inside of cab

asked by: Bob

Expert Reply:

A circuit tester like # PTW2993 on the 5 o'clock pin should only light up when you use the manual override function on a brake controller. This is what the blue wire from a brake controller connects to and it is the output wire. You need to have the black power wire running to the brake controller to provide the 12V power needed for that output to be effective.

If you have the factory 7-way the harness will be there under your dash. If you do not, then the connection under the dash is still there, but there will either be a bundle of wires or the factory round connection just above the spare tire that will need to be connected to ensure the wires allow the proper functions. I've attached a help article on connections on your year/make/model to assist. There is a blue and red wire near the fuse box that do need connected. The article helps with the locations and has photos to assist.

expert reply by: Jason S