Location of a Dedicated Brake Light Wire for a Camper Shell on a 2009 GMC Sierra Duramax 3500
Question:
Want to wire in my canopy brake light, cant find a dedicated wire at back, where else would I look, any info would be most appreciated. Thank-you
asked by: Howard S
Expert Reply:
You can find a dedicated brake light wire under the dash, below the steering column to the left and above the brake pedal. This wire is normally used for a brake controller. There will actually be a bundle of wires held together with white tape. The tape should have the functions of the wires on it. The wire you need is most likely a light blue wire. Test it with a circuit tester, like #PTW2993, to be sure it is the correct wire. It should show ONLY show a signal when the brake pedal is pressed.
If that wire is in use by a brake controller, there is another location you can use. It is on the brake switch located above the brake pedal. There will be numerous wires going in and out of the switch, so you will need to test the wiring using a circuit to find the one that carries a signal only when the brake pedal is pressed. If it shows a signal with the lights on or turn signals engaged, it is not the correct wire.
Using either of these locations will require routing the wire out of the cab somehow. I recommend routing it through the fire wall through an existing grommet if available. If not, you will have to drill a hole. Be careful when drilling because there may be components on the other side of the fire wall and you would not want to drill into them.
