How to Determine Functions of Brake Controller Harness on a 2008 Hummer H3

Updated 05/31/2019 | Published 05/30/2019

Question:

I am attempting to wire my electric brake controller. My 2008 H3 Hummer has a green , orange, brown and black wire with a white stripe. Cant find a proper wiring diagram to hook it up.

asked by: Terry

Expert Reply:

The best way to determine what functions each of those wires on your 2008 Hummer H3 carries is to use a circuit tester like part # PTW2992 and check to see what each wire does. I tried looking up what functions they might carry but the only thing that seemed to be consistent is that the orange wire has constant 12V power to it. You can verify this by connecting the circuit tester to that wire and seeing if it has constant power or not.

The typical brake controller wiring pigtail has white, blue, black, and red wires. You will need to connect them to the following functions that you find:

Blue - 7-Way Output to Trailer
Black - 12V Power
White - Ground
Red - COLD Side of Stop Light Switch (only gets hot when brake pedal is pressed)

expert reply by: Jon G