Troubleshooting Trailer Brakes that are Locking Up Whenever Connected to Tow Vehicle

Question:

I tried to get my trailer from storage and when I hooked it all up the brakes were lock on . After trying to free them up by moving back and forth the wheels would roll but with a heavy drag on them . When I unplug them I hear them release and it towers freely . Plug back in and they engage . I replaced controller but nothing changed , any ideas ?

asked by: Paul Z

Expert Reply:

On your tow vehicle's wiring you have a short between the 12 volt accessory circuit and the brake output circuit which is putting 12 volts on the brake circuit whenever it's connected. It could be on either the vehicle or trailer side of the wiring so go over both looking for any obvious signs of a short like cuts or exposed wire and fix as needed.

expert reply by: Jameson C