Brake Controller Will Not Adjust and Digital Meter Shows Voltage Issue

Question:

My Reese pilot brake controller is showing 13 and will not adjust and when I test wiring at the breaks it shows a negative 12.42 volts. Shows positive voltage at the connection from truck to trailer.

asked by: Dan W

Expert Reply:

I contacted the manufacturer and have a different way for you to check to see if your brake controller is able to work properly. They suggest not using the digital multi-meter because it doesn't actually pull any power, so the brake controller doesn't respond the same way.

First, unplug your trailer and check to see if the "c" goes away on your controller. If so, use a 12-volt incandescent circuit tester, like # PTW2993, because the light bulb will actually draw some amperage that will be noticeable to the brake controller. Connect the alligator clip of the tester to a solid and clean ground then test the blue electric power brake wire behind the 7-way connector with the tip of the tester while engaging the manual override. The bulb should light up. Then check the brake controller, as now it should show "c" and should be able to adjust up and down.

If this doesn't work, you have a short somewhere from the electric brake control output wire. To find a short, first test for power at the vehicle side trailer connector for electric brakes (the 5 o'clock pin). If there is no power at the connector, then move to the cab and cut the blue wire about 6 inches behind the brake controller and test that wire coming from the controller for power. If there is no power when you engage the manual brake override, then we know there is a problem with the controller.

If there is power and you are able to adjust the power gain, then we know there is a wire issue between the controller and the 7-way. Simply run a new 10-gauge wire to resolve this issue. If there is power, but the brake controller still reads 13 and you cannot adjust the power, then there is a problem with the brake controller itself and it will have to be replaced.

Once the tow vehicle and brake controller are functional, then reconnect the trailer. If there is still an issue at that point, you will want to check the brake wires on the trailer for a short.

expert reply by: Jason S