Installing a Brake Controller on a 2008 GMC Yukon Denali XL AWD with Factory Tow Package

Expert Reply:

To install the Tekonsha P2, # 90885, in your 2008 GMC Denali, there are only a few simple steps to follow.

With a factory tow package, all you will need is the brake controller itself. The unit comes with blunt cut wires that will need to be installed to the factory tow package wiring harness on your vehicle. This harness is located under the dash, to the left of the brake pedal, and usually held together with white tape. Pull the harness down and you can begin to connect the brake controller wires.

The colors of the harness probably will not match the brake controller wire colors, so you will have to test them with a circuit tester like the Quickee # 3808. Turn the vehicle on (it does not have to be running, though it can be).

Using the circuit tester, on your vehicles wiring harness, find the wire that carries a signal all the time. This is the 12 volt lead. It connects to the black wire on the brake controller. Next, find the wire that carries a signal only when the brake pedal is pressed. This wire will connect to the red wire of the brake controller. The white wires on each will be the ground. Connect them together. That leaves one last connect; the blue wire on the brake controller will connect to the remaining wire on the brake controller. I have included a link to the instructions for the brake controller below.

If you do not have a factory tow package, you will still follow the steps above, but you will also need to install a Replacement Multi-Tow 7-Way and 4-Way Trailer Connector, # 30955. This will plug in under the vehicle, above or near the spare tire. This will give you both a 4-Way and 7-Way connection at the rear of the vehicle. I have included a picture that shows what the connection point looks like.

expert reply by: Michael H