How to Correct P-3 Brake Controller Error Message

Expert Reply:

If you are receiving the Open Ground error message, you will want to check all your ground wires to make sure they are still firmly connected to a suitable grounding location. The brake controller, vehicle connector, and trailer connector must all be grounded in order for the unit to function properly. Make sure the grounding locations are not covered by any paint or rust.

If you are receiving the Output Shorted error message, I recommend checking the length of your blue electric brake wire on the vehicle and trailer to make sure there are no pinched or exposed points that may be touching part of the frame and causing a false ground.

Sometimes, testing the system with a test light or non-Tekonsha brand testers can also cause the Output Shorted message. In this case, I recommend disconnecting and reconnecting the brake controller unit.

You can also try disconnecting the blue wire from the brake controller. If you still get the Output Shorted error message, the problem would lie in the controller itself. If not, the problem would be located on the blue wire running to the trailer connector, or on the trailer itself.

Another area to check on your trailer would be the brake magnets. You can make sure that the magnets are still in good, working order, and that they are still firmly grounded.

expert reply by: Sarah L