How To Test A Faulty Braking Circuit

Question:

I am having major issues with this controller. Was working fine last two trips I took hauling my trailer and now its not. Apply the brakes and starts to work then quits working. Red screen saying there is a short. While this screen is showing i can apply the manual brake and it works. Crank the power way up and it works most of the time but not like it should. Going slow it grabs when i barely touch the brakes. Way too much power going to the brakes. This is scary as hell traveling over passes and through big city traffic on an interstate. This is dangerous!!! I am hauling horses and this unit was bought less then two months ago. I need this fixed asap!!

asked by: Shelley K

Expert Reply:

It sounds to me as if you have a short on either the trailer or vehicles wiring harness. However, before you begin to test each of these connections, you will first want to ensure the trailer connectors are free of dirt, debris, and corrosion in addition to making sure all grounds on both the trailer and vehicle are secure.

To determine whether the wiring issue is on the vehicle or trailer, you will need to use a circuit tester like part # PTW2993. Before you begin, visually check all trailer wiring on the vehicle for any damaged sections that need repair. You will then want to test the pins in the vehicle's trailer connector using the circuit tester. If power is passing through the connector, then the problem is likely on the trailer side. If power is not passing through the connector, the problem is likely somewhere on the vehicle. To test the vehicle wiring, you will need to sever the brake controller wire about 6" back from the brake controller

To test the trailer's brakes, you will again want to visually check that all connections are secured to the back of the trailer connector and to the trailer's brakes. Look for any damaged sections that could be causing a short. I also recommend checking the main trailer ground and the brake magnet grounds for corrosion or loose wires. A weak ground could cause intermittent performance. I would also open up the trailer connector and look for internal corrosion or loose wires.

If you still cannot trace down the problem using the steps listed above, feel free to contact me and I would be happy to offer further advice.

expert reply by: Conner L