P3 Brake Controller Shows No Trailer Connected on a 2013 GMC Sierra

Question:

I have a 3500 GMC, U-Haul hooked up my p3 brake controller but when I hook to my trailer it say no trailer, do I need to run a wire from my controller to my plugs

asked by: Fred D

Expert Reply:

There are some connections that need to be made under the hood of GM trucks like your 2013 GMC Sierra to make everything fully functional. It does sound like the blue wire from the controller to the 7-Way is not ran all the way. We have a help article which I have linked that will also help.

If the brake output wire is not ran all the way back to the 7-Way then yes you would have to manually run a wire. I recommend using 10 gauge wire # 10-1-1 which is sold by the foot.

expert reply by: Michael H