Wiring a Brake Controller on 2008 GMC Sierra

Updated 09/01/2017 | Published 08/31/2017

Question:

I have a 2008 sierra and my factory brake controller wires are as follows: dark blue,red with black stripe, green with white strip, yellow and orange. I have watched videos that show: Dk blue,red/black,white, light blue and orange which is auxiliary and not used. They were all with taped ends bunch up in the location as shown in the videos. Help!

asked by: Robert

Expert Reply:

I believe I can help you out, but it may take a little bit of trial and error. With your 2008 Sierra we know that the dark blue wire will go to the blue wire of the brake controller and the red with black stripe will go the black wire.

That leaves us with only the green with white strip and yellow wires. What you'll want to do is use a circuit tester such as # PTW2993 and test both the green/white and yellow wires when you press the brake pedal. The one that gets power will connect to the red wire of the brake controller, which is the brake light signal wire, and the other wire will be your ground wire and connect to the white wire of your brake controller.

I've added a link to a couple help articles on wiring brake controllers which you also may find useful.

expert reply by: Kyle S