No Power to Brake Controller After Installation on 2008 GMC Sierra

Question:

I followed your install and it was great, But I do not have power to the brake controller, the power to the 7 plug is there but I do not know which fues is for the brake controller and it is not on the box info please help 2008 GMC Sierra 1500

asked by: Jon Z

Expert Reply:

On your 2008 GMC Sierra, you will want to check the power distribution box located under the hood of your vehicle, on the drivers side. If you remove the cover of the box there will be two power posts located at the front of the box. The left power post should have a red wire attached to it. The red wire is the power wire for the brake controller. You will also want to check the 30 amp fuse adjacent to the power post to make sure it is installed and working. This fuse is what activates the power post for the brake controller.

The power post to the right will be for the power to the 7-Way trailer connector. Since you have power to your 7-Way, the wire will already be connected and should have a 40-amp fuse installed next to it.

If the fuse locations are not listed on the top or underside of the power distribution box cover, I would recommend to also check your owners manual for the locations of your fuses.

I am including a link to a FAQ page on a brake controller installation for a 2008 GMC Sierra. This page will show you a step-by-step installation for the brake controller with pictures. It will show you the wire connections and the fuse locations.

If the wires are installed and the fuses are there and working properly I would recommend to check your brake controller wiring. The 2008 GMC Sierra comes with a bundle of wires underneath the dash, instead of a brake controller plug-in adapter. These wires are connected to the wires on the brake controller. You will want to check to make sure the wires are all connected properly.

expert reply by: Jeff D