One out of Four Trailer Brakes Does Not Work with Brake Controller but Does with Break Away System  

Question:

Expert Reply:

You will need to make sure that all of the grounds for the brakes and the break away system are attached to clean and corrosion free bare metal surfaces. Inspect all of the wiring to make sure there are no loose or frayed wires. And make sure that the trailer connectors on the vehicle and trailer are clean and free of corrosion inside and out.

To check to see if the brake controller is putting out enough power adjust it to the maximum level. Then use a multimeter such as # PT89ZR to test the brake output pin on the vehicle side connector. Have someone sit in the truck and fully apply the manual override.

You should be around 11 or 12 volts at the trailer connector and the same at the magnets. Any significant drop (more than a couple volts) indicates a problem in the wiring that will need to be tracked down and fixed.

The difference between getting power from the trailer brake controller and power from the break away system is that the power is closer when using the break away system. There may not be enough power getting to the brake assembly from the controller.

If you were to disconnect the other brakes and leave only the one that is giving you trouble connected, it may start working. If it does then I would run T-off from the main power wire to front two assemblies and then T-off to the second two. That way you have power going to both front assemblies at the same time.

If this causes the rear assemblies to stop working you may need to change the wire gauge to larger or smaller (depending on the nature of the problem) and turn up the power output on the controller.

expert reply by: Michael H

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