Troubleshooting Low Power to Trailer Brakes form New Brake Controller on a 2007 GMC Sierra

Question:

I have a 2007 GMC Sierra and just installed a trailer brake controller, everything works fine except the trailer brakes. When I hook up a volt meter and check voltage when I apply the brakes I only get about 2.9 volts. When I use the manual lever on the controller I get max voltage of about 13.5 volts. What are some of the things that i should check on the truck as it appears to not be a controller problem.

asked by: David H

Expert Reply:

It sounds like you are using a proportional brake controller like the Prodigy P3 # 90195 on your 2007 GMC Sierra. If this is the case then there is an internal inertia sensor that helps to determine how much power to send back to the trailer brakes. Since your pickup is sitting still when you apply the brakes with your foot the brake controller and tell that the vehicle isn't moving so it only sends a little power. When you use the manual override it sends max power even though you aren't moving. The brake controller will send the correct amount of power once your towing setup is actually moving.

If you have a time-delayed brake controller then something internally is wrong with the controller and it needs to be replaced. The Prodigy P3 # 90195 I mentioned above is an excellent option that has received high praise from our customers as you can see on the product page.

expert reply by: Jon G