Troubleshooting Trailer Brakes that Lock Up When Brakes are Touched

Question:

My brakes lock up momentarily,even with the power output turned down below 3, boost off,going over 50 km/h with a tandem axle trailer that is new with electric brakes, brake controller set to electric, mounted to specs in book. It is in a 2006 Ford F250 Super Duty.

asked by: JOHN W

Expert Reply:

I'd check to see if one of your stop turn circuits is shorting out to the brake output circuit of the trailer wiring which is why the trailer gets full voltage when the brakes are touched and lock up. You can test this pretty easily by putting on the blinkers and see if the brakes lock up if you are moving or click if parked. If so, you need to go over the wiring of the two circuit and see where they may be shorting out. Typically this is near the 7-way.

expert reply by: Jameson C