Troubleshooting Trailer Brake Controller Wiring on a 2009 GMC Sierra 3500 with 6 Wires

Updated 10/25/2022 | Published 10/24/2022

Question:

I have a 2009 GMC 3500 pickup. It had a brake controller installed and I wanted to replace it with a new one due to an electric failure. The wires going to the installed controller are 2 yellow wires, one black wire, one blue wire, one brown wire, and one green wire. My new controller only has four wires: black battery, red brakes, white ground and blue brake output. Can you tell me how to connect the existing wires to my new brake controller?

asked by: Mark H

Expert Reply:

I do not understand why you have 6 wires going to your brake controller on your 2009 GMC Sierra 3500. The factory wiring located near the brake pedal will be red/black(battery power), white(ground), light blue/white(brake signal light), dark blue(output to trailer) and an orange(center mount stop lamp) that is not used. I would trace the wires that you have to these wires to verify what their proper function is. You can also use a Multimeter # PT89ZR to verify which wires have power and the ground wire. This will allow you to install the Tekonsha P3 Brake Controller # 90195 with its included harness.

expert reply by: Bud M