Troubleshooting Trailer Brakes that Lock up When Brakes are Touched

Updated 08/03/2017 | Published 08/02/2017

Question:

as soon as i touch brake pedal on truck, trailer brake skid tires on trailer ,but when i go to adjust the brake controller following there steps it tells me no trailer connected i go menu,go to electric brakes, highlight it ,hit ok,go to confirm ,hit ok, then get red screen telling me no trailer connected with the trailer plugged in .

asked by: James B

Expert Reply:

What's happening is that your stoplight circuit is shorting out to your brake output circuit. I bet if you were to put one of the truck's blinkers on the brakes would pulse with the blinker.

I'd also be willing to bet the right blinker is the one that would cause it to pulse as well. Reason I say that is because the brake output circuit and the right turn/stop circuit of the trailer 7-way are right next to each other on the connectors. Check out the diagram I attached for more info.

Check the inside and outside of both the connector on your vehicle and the connector on your trailer. Look for any corrosion or cut/exposed wire and fix as needed.

expert reply by: Jameson C