Locating Brake Switch Wire on 2015 Chevy Silverado 3500

Question:

I have a 2015 chevy Silverado 3500 HD w/integrated trailer brake sys I am having trouble w/loosing trailer connection. I want to bypass the system and install an after market controller tekonsha P3 I have it all installed from battery to a new trailer plug connector in the bed ran a new wire harness totally bypassing oem harness what I need to know is which wire is the brake wire I should tap into for the red wire of the P3 controller I work in a body shop for over 40 years so I have the ability to do this I just need a little help locating the correct wire so I dont create another problem I have not seen a brake switch like this b4 it is at the end of a shaft on left side of brake pedal w/multiple wires the shaft rotates within the switch if you could help with this I would be very greatfull I have done business with you b4 but have never had to ask for help hopefully you will have the answer I need thank you

asked by: John

Helpful Expert Reply:

If you are wanting to hardwire the Tekonsha P3 Trailer Brake Controller # 90195 (great choice!) to your 2015 Chevy Silverado 3500 that has the factory controller, you will just need to locate the cold side of the brake light switch. This is the wire on the harness you mentioned finding that will only receive power when the brake pedal is pressed, and none with any other function. I recommend using a circuit tester like # PTW2993 to verify the correct wire, which will indeed be connected to the red wire coming from the brake controller. I was unable to confirm what color wire this will be on your truck, but you can start by testing a light blue wire if one is present, as this is the color that was used on previous model year Silverados.

Instead of hardwiring the controller, you can also use the Plug-In Wiring Harness # 3016, which will plug right into the built-in port beneath the dash. This way you won't have to worry about finding the correct wires on the truck, as this will be a simple plug-and-play installation. Just note that the blue wire from the Plug-In Adapter will need to be run back to the 7-Way connector with a length of 10 gauge wire # 10-1-1, which is sold by the foot. You will remove the wire that is in the 7 o'clock position on the 7-Way and connect this new wire to it.

expert reply by: Chris R