Why Would Trailer Brakes Lock Up without Brake Controller When Vehicle Brakes are Touched

Question:

my trailer brakes lock up when i hit the brakes even though i dont have a brake controller in the truck. Why?

asked by: John

Expert Reply:

When this happens it means the stoplight circuit is shorting out to the brake output circuit. I bet if you turned on your blinkers one side would cause the brakes to intermittently lock up too.

What you need to do is go over the wiring of the trailer and vehicle (starting with the connectors) and look for any obvious signs of a short and fix as needed.

expert reply by: Jameson C