Installing a Trailer Brake Controller on a 2007 Chevy Avalanche

Question:

Under dash wire bundle has four wires with label: AUX, Batt, CHMSL, and GND. I attached the loose Blk/Red wire under the hood to the battery giving power to the wire AUX and attached it to Blk on controller. Attached Wht GND wire to Wht on controller. Attached Blu AUX to Blu on controller. The only wire left is the CHMSL. It has a constant 12 volts. Can find no wire that responds to the brake pedal. Tried putting vehicle in gear in case PARK set 12 volts to CHMSL. No help. Am I missing the Brake Pedal wire? Should I have 5 wires in the factory wire bundle under the dash?

asked by: George M

Expert Reply:

There should actually be 5 wires. On your 2007 Chevy Avalanche the red/black wire goes to brake controller black for 12-volt power. White goes to white for ground. Dark blue on the truck goes to blue on the controller.

That leaves the brake controller red wire. There should be an orange wire that is the CHMSL circuit. Do not use that wire. You actually need a light blue/white wire to connect to the brake controller red wire. I have linked a video and a help article for you that should help.

If you cannot find the light blue/white wire then you would need to use a circuit tester, such as # PTW2993, to test the brake switch wires above the brake pedal. You need the one that only shows power when the brake pedal is pressed and not when the headlights or turn signals are on.

expert reply by: Michael H