Troubleshooting Trailer Brakes In Over Load

Question:

I had to change my trailer axles a year ago, the brakes worked good until i changed the axles. the problem i am having is when i put the brakes on my trailer brakes go into over load, and one brake locks up and has ruined a tire, this happens intermittengly, some times the brakes work properly then the next time the brakes will not work and go into overload. i changed the controler and bought a prodegy and i am still having the same problem. Thank you

asked by: Darryl

Expert Reply:

Since you recently replaced the brake controller you will want to do a quick check there. They have to be mounted in the direction of travel, cannot be tilted or turned side to side, and usually have to stay within a certain range pointed nose up or down. If that is off, it can cause the brake controller to perform erratically.

Next I would try some testing. Disconnect the trailer from the vehicle, then use a circuit tester like # PTW2979 if needed to test the connector on the vehicle. Have someone sit in the truck and run through the various functions to make sure everything is working. If any of them are showing a constant 12 volts, and the matching pin on the trailer side goes to the brakes, that would be why the brakes lock up. Also check for any corrosion on the vehicle and trailer connector sides that could affect performance.

The trailer brake magnets could have a short as well. Check the wiring for any frayed wires that might be touching bare metal. Make sure the grounds are attached to clean and corrosion free bare metal surfaces. Visually inspect the magnets and if you can see the windings coming through then the magnets need to be replaced.

You will want to inspect your brake shoes to make sure you don't have any grease on them. Also look at the included video resource walking you through adjusting your brake shoes. Finally your shoes themselves maybe cracked or broken.

To further test the magnets you can follow the FAQ article I have linked. I have also linked additional FAQs on brake controller troubleshooting and trailer wiring for you.

expert reply by: Patrick R