Constant Power on Blue and Red Trailer Brake Controller Wires on 2007 Cadillac Escalade

Question:

Hi 2007 Escalade w/ elec brake controller. Checking wires at controller and found that the light blue harness wire from the brake switch reads 10v with the brakes off, then higher if you step on brakes. Should this have power with brakes off, and key on? I was also getting a 5.67v reading with brakes off and controller off, at the terminal for the electric brake in the 7 prong connector outlet in the rear of the car. Same reading from the blue wire at the controller end.

asked by: Al S

Expert Reply:

There should not be power all the time on the red wire or on the blue wire on a brake controller. You should not have to connect the red brake controller wire to the brake switch. You should be connected to the tow package wiring under the dash, to the left of the emergency brake pedal.

There is a bundle of wires held together with a white tag. There should be a light blue wire here that you would use but not at the brake switch. It is also possible that if you are connected to the tow package wire bundle under the dash that you are connected to the illumination circuit and not the stop light wire. You would need to use a circuit tester to test the wires to determine the functions to be sure.

If you were to disconnect the brake controller red wire and the voltage goes away on the blue wire then the issue is that input connection. But if the voltage remains on the blue wire that can indicate a short circuit. Make sure the vehicle and trailer side connectors are clean and free of corrosion inside and out.

I have included a link to an FAQ article showing the typical under-dash connections for you. I have also included a link to our FAQ article on troubleshooting brake controllers because it could be an issue inside the brake controller as well.

expert reply by: Michael H