How to Install a Brake Controller in a 2002 GMC Envoy

Question:

I have a connector already installed under he dash I got the vehicle this way. Please see the attached photo. I would like to install a Prodigy 3. Can you tell me what adapter I should use? Or is there another controller that would work better? Thanks!

asked by: Chris M

Expert Reply:

The plug in your picture is the OBD II port which is on every vehicle made for the US market since 1996 but you cannot plug a brake controller into it.

But you won't need to on your 2002 GMC Envoy because if it came with a factory installed 7-Way trailer connector then there are already tow package wires tucked up under the dash, to the left of the steering column, held together with a white tag like in the video I have linked showing a TrailBlazer (which was built on the same platform as the Envoy for that generation).

The white tag should provide the functions of the tow package wires but it should be dark blue for brake output which connects to the blue brake controller wire. Then there will be an orange wire which will connect to the controller's black wire for 12 volt power. The black wire on the vehicle will go to the controller white wire for ground. And the vehicle light blue wire will go to the controller red wire for input from the brake switch.

expert reply by: Michael H