Pilot Brake Controller Only Shows One Red Dot with Trailer Connected and No Numbers with Override  

Question:

Expert Reply:

If you are seeing just the dot with a trailer connected and it does not change when you use the manual override knob or the press the brake pedal that indicates a poor connection on the brake output wire.

This can be caused by a dirty or corroded trailer connector. Check the vehicle and trailer side trailer connectors and make sure they are clean and free of corrosion inside and out.

You can also test the brake controller. At the back of the truck, you can test the brake output pin for proper power using a circuit tester such as # PTW2993. Have someone sit in the truck and apply the manual override while you test with the circuit tester. If the proper power is getting back to the trailer connector, then the issue is on the trailer side. If not, then further testing of the brake controller is needed.

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 # 3808 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 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.

expert reply by: Michael H

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