Wiring harness for brake controller on 2000 GMC Pickup

Expert Reply:

Is the harness you have aftermarket or the OEM? The aftermarket Wiring Adapters we carry, such as the part number 20263, have 4 leads which would wire up color for color with the wires coming off of the back of the wiring harness. If you have the OEM harness, it would have 5 leads, and would wire as follows: the red harness wire would connect to the black wire on the brake controller, the light blue harness wire connects to the red brake controller wire, the black harness wire connects to the white wire on the controller, and the dark blue harness wire connects to the blue wire on the controller. The brown wire on the harness is for an illumination circuit, and is not needed. That wire would be taped up out of the way. The aftermarket or OEM harness would simply plug into the junction box located on the firewall behind the emergency brake pedal. I'm not aware of a harness that would have 6 wires. My guess is that it is the wrong one for the vehicle.
For reference, I'll also give you a link to our Brake Controller Installation Guide for GM Trucks. The link can be found below.

expert reply by: Mike L