Troubleshooting Trailer Brakes that Lock Up

Question:

Why would my trailers brake engage while truck is in drive

asked by: Jesus

Expert Reply:

Trailer brakes that lock up can be related to several problems. If they lock up when the trailer connected is connected that would indicate that the 12 volt accessory circuit is shorting out to the brake output circuit on the trailer which is causing the brakes to lock up. You would want to check the wiring and trailer connectors of both the vehicle and trailer looking for any obvious signs of shorts such as cut or exposed wire, or corrosion and fix as necessary.

Or if you have a 6-way trailer connector most likely you have the 12 volt and brake output circuits swapped as there is two common ways to wire up a 6-way and if you have the wrong setup the brakes will lock up.

expert reply by: Jameson C