2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 459

Electric Brake Control Wiring Provisions These wiring provisions are included with the vehicle as part of the trailer wiring package. These provisions are for an electric brake controller. The instrument panel contains blunt cut wires behind the steering column for the trailer brake controller. The harness contains the following wires: ... Dark Blue: Brake Signal to Trailer Connector Red/Black: Battery Light Blue/White: Brake Switch White: Ground If the vehicle is equipped with the "Heavy-Duty Trailering" option, please refer to "Heavy-Duty Trailer Wiring Package" earlier in this section. When the camper-wiring harness is ordered without the heavy-duty trailering package, an eight-wire harness with a seven-pin connector is located at the rear of the vehicle and is tied to the vehicle's frame. It should be installed by your dealer or a qualified service center. If the vehicle is equipped with an ITBC, the blunt cuts exist, but are not connected further in the harness. If an aftermarket trailer brake controller is installed, the ITBC must be disconnected. Do not power both ITBC and aftermarket controllers to control the trailer brakes at the same time. 5-83