Troubleshooting Trailer Brakes That Lock Up

Question:

Why do my brakes lock up when trailer moves forward even with brake shoes backed way off and all power on hooked This is a new trailer and made sure the axle is headed the right way? Thanks

asked by: William K

Expert Reply:

If your trailer has electric drum brakes then a few things could cause them to lock up when they should not be applying at all.

There could be a short somewhere in the wiring that is causing 12V power to reach the brake magnets. Bad corrosion inside a connector could cause two circuits to become bridged together. You could also have an issue with your breakaway system that is sending power to the brakes, such as a bad breakaway switch.

Another possible cause is use of a wiring adapter between the truck and trailer. Adapters can have a different pin out that causes one vehicle circuit to connect to another different circuit on the trailer.
Some adapters could allow the 12Vauxiliary circuit to connect to the brake circuit.

Please tell us more about the specifics of the trailer and truck and we can better help you determine the cause for the malfunction.

expert reply by: Adam R