Brake Controller Loses Power when Trailer is Connected to 2010 Chevy Silverado

Question:

hi, I connected my brake controller according to instructions here and it appeared to work, the red light came on with the brakes and manually. The next day I connected to a trailer and tested and now the red light no longer comes on manually or with the brake pedal. I checked all the connections and the fuses. What is the problem?

asked by: Ryan T

Expert Reply:

Just to make sure the brake controller was wired to the correct tow package wires on your 2010 Chevy Silverado I will go over the functions.

On the truck the red wire connects to brake controller black. Dark blue on the truck goes to brake controller blue. White goes to white. There will either be a light blue or orange wire left if not both. One of them will connect to the brake controller red wire. Both likely have the brake input signal. If one is not working with the trailer connected, then try the other one.

If you still have problems disconnect the trailer and see if the problem goes away. If it does, then the issue is on the trailer or one of the connectors. Make sure the truck and trailer side connectors are clean and free of corrosion inside where the wires attach as well as on the pins.

Also make sure you have made the under-hood connections outlined in the help article I have linked.

You can do some further testing. In the truck cab you will need to sever the blue wire several inches from the back of the controller. Then use a circuit tester such as # PTW2993 to test the end of the blue wire coming out of the controller. It should only have power when you apply the manual override. If it shows power at idle, then there is something wrong with the controller and it will need to be replaced.

If it tests fine, then reconnect the blue wire. Then move on to the truck side trailer connector. Many times, dirt or corrosion can cause a short in a trailer connector. Make sure the truck and the trailer side connectors are clean and free of corrosion inside and out.

You can test the brake output pin and it should only show power with the manual override. If it shows power any other time, then there is a short somewhere between the connector and the brake controller you will need to track down.

If the truck side checks out fine, then it could be the wiring to the brake magnets or the magnets themselves. Inspect the power wires to the magnets and look for pinched, frayed, or damaged wires and fix as needed. Make sure the ground wires are attached to clean and corrosion free bare metal surfaces.

You can visually inspect the magnets and if you can see the copper windings coming through the magnets will need to be replaced. To further test the magnets, you can follow the help article I have linked. I have also included some help articles on testing and troubleshooting brake controllers for you.