How to Bypass Factory Brake Controller of 2015 GMC Sierra 3500

Question:

Hello, I have and no trailer brake output from either of my 7 pin plugs. I have tested with a meter and a tester and I bought the actual 7 pin plug tester and it also shows no output. Truck has been at the dealer once and they changed the brake controller above my spare tire and I tested it with no power. Basically when I set my gain all the way up, and its factory. I have no change in voltage at either plug. Thoughts?

asked by: Joe M

Expert Reply:

If it's a factory brake controller only a GM dealer will be able really fix it since it's their controller. We could help you bypass it if you wanted to but only they will be able to get your factory controller to work right.

In order to bypass your factory installed controller and install an aftermarket brake controller like the Prodigy P3 Trailer Brake Controller, # 90195, with Plug-In Wiring Adapter, # 3016, you will have to make a couple of cuts and connections.

First you will cut the blue wire on the plug-in wiring adapter and connect it to enough 12-gauge blue wire to reach the rear of the truck. Now at the 7-way trailer connector at the back of the truck, you will cut it's blue wire approximately 4 to 6 inches from the connector and connect it to the blue wire that was run from the brake control wiring harness. I recommend using Deka Heat Shrink Butt Connectors, # DW05745-10, and electrical tape when making all electrical connections. Now you are ready to plug the wiring adapter into the brake control port up under the dash and into the back of your new controller.

expert reply by: Jameson C