Troubleshooting Brake Controller Only Working at Max Setting

Published 09/22/2021

Question:

We have a fifth wheel travel trailer. We pull this trailer with a 2020 f-350 truck. The trailer brake controller in the truck has been set on 10 which is maximum braking. In our last trip the controller ped to no brakes when we were stopping. The controller being digital, we pushed the minus button until it showed zero, then we pushed plus until the number was 5 or above. The brakes will work again for a short time then quit. Is this problem the controller or a resistor? We have installed new brake magnets.

asked by: David B

Expert Reply:

The first thing I recommend doing is checking the trailer and the tow vehicle connection. Often times there can be issues with corrosion build up. It never hurts to check and clean the connection. I would also check all of your ground connections and make sure they are secure.

From there, I would check out the brake controller output. Using a circuit tester like the # PTW2993, you can test the brake output pin on your 7-way with the setting at 10. If you find there is no problem then you can rule out the brake controller because it is doing its job. If the power is low, then it may be the problem. Try checking the ground connection as well as the connection to your brake controller wires. If it uses the plug in style wiring harness, try unplugging it and plugging it back in to make sure it is well seated. If all of the connections are good it is time to check the wiring for a short.

If you don't have an issue with the brake controller, it is likely your brakes need to be adjusted. This is often the problem when the brake controller needs to be set to the max for the brakes to work. I have attached a helpful article on adjusting trailer brakes as well as troubleshooting brake controllers for your reference. If you are still unable to fix the problem feel free to reach out and I will help you troubleshoot further.

expert reply by: Robin H