What Would Cause Trailer Brakes to Lock Up When Brakes are Touched

Updated 02/05/2021 | Published 02/04/2021

Question:

I have a technical question, I have a customer using a brake controller rated for 2 to 4 axles. If they are towing a single axle trailer with brakes would the controller cause the brakes to lock up even when turned down due to not enough axles?

asked by: John R

Expert Reply:

If a brake controller is rated for more trailer axles than what the trailer has it would not cause the brakes to lock up but I believe I know what's going on.

If trailer brakes are locking up when you touch the brake pedal that typically indicates that the problem is the stoplight circuit being shorted to the brake output circuit. You can test this by putting on the blinkers of the tow vehicle and if the brakes intermittently lock up with the blinker this would prove this.

expert reply by: Jameson C