My Trailer Brakes Are Working With One Of My Trucks, But Not The Other, How Do I Resolve This Issue

Question:

On my 2021 GMC sierra 3500 HD, I have a 2019 Kaufman trailer. Service trailer brake system message pops up and on the trailer brake controller there is no gain coming out. I also have a 2021 GMC Sierra 1500 so when I put the connection into that truck the brake controller shows output in the trailer gain while connected to my 1500 and not the 3500. What would be the best way to resolve this issue on my 3500 HD to regain electricity to the brakes on my trailer.

asked by: Jonny

Expert Reply:

Since your brake controller is working for one truck and not the other, the issue is with the truck's connections, not your brake controller. Your 7-way connector is not providing power at the rear of your 2021 GMC Sierra 3500, for your brake controller. I would take a circuit tester, something like the Hook Probe Circuit Tester, part # PTW2993, and check to see if there is any power coming from the corresponding connector. It will be the lower right if you are looking at the 7-way at the rear of your truck. Once this is verified, you can check the connection of your brake controller wire. It is the blue wire on your 7-way connector.

I have included a product description link and a video review link below.

expert reply by: Mark Smith