Troubleshooting Low Brake Controller Output Voltage  

Question:

Helpful Expert Reply:

The first thing I'd check is troubleshoot the controller. Make sure you have a full 12-v being delivered on the black wire, and 12-v exiting the blue wire with the controller gain turned all the way up and with the brake pedal (assuming it's a time-delayed controller. A proportional controller won't put out voltage with the brake pedal unless the vehicle is in motion). I'll link to an article that explains how to troubleshoot a brake controller.

If you're getting full output from the controller but just a fraction of that at the trailer connector, there's either internal corrosion or damage at the trailer connector and it should be replaced or a poor connection somewhere in the output circuit between the controller and the trailer connector.

If the trailer connector looks okay, check how much voltage is showing on the blue wire feeding the trailer connector. If you're not showing full voltage there, there's a poor connection somewhere in the output circuit between the controller and the trailer connector. You can try to hunt down the loose or corroded connection, but this could be the easiest way to handle this would be to get a length of # 10-1-1 10 GA wire long enough to reach the trailer connector from the brake controller. Sever the blue wire exiting the rear of the controller and the rear of the trailer connector and splice in a new output circuit which should solve the problem.

expert reply by: Mike L

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