Troubleshooting Brake Controller That Puts out Voltage When Vehicle is Parked

Question:

I have an 03 dodge that i installed the brake controller in. I have noticed with the third brake light on my cap and the brakes on my trailer that whenever there is any load even led 3rd brake light on controller that it sends a pulse about every 6 seconds. This causes the 3rd brake light or the trailer brakes to activate even when truck is parked and not running. Getting tired of disconnecting everything to keep from getting premature failure of components. please help.

asked by: Randall A

Expert Reply:

It sounds like the controller might have an internal short that is feeding back into the vehicle, causing the brake light to illuminate.

You can test this by using a circuit tester like part # PTW2993 on the red wire exiting the rear of the controller. There should be no voltage on that wire unless the brake pedal is pressed. If you see any intermittent voltage, it would indicate a short in the controller, which would then need to be replaced.

The Prodigy does send a bit of output voltage (1-1-1/2 volts) to verify that the trailer is connected, but that voltage is insufficient to actuate the trailer brakes.

Another possibility is that there could be corrosion built up in the interior of the trailer connector that is allowing voltage from the 12-volt power supply circuit to bleed into the brake output circuit. If you can see white or green corrosion on the pins of the connector, it indicates that there could be corrosion on the interior of the connector at the terminals where the individual wires attach to the connector.

To see video about troubleshooting a brake controller, click on the provided links.

expert reply by: Mike L