Troubleshooting Brake Output Pin on 7-Way Connector Putting out Constant 12-Volts

Published 11/18/2009

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Question:

On the back of a toyota tundra , the 7 pin trailer harness are youn suppose to have 12 volt output on the pin that say trailer brake at all time?

asked by: nick

Expert Reply:

I am guessing that either your trailer connector is wired incorrectly or there is a problem with your brake controller.
The only pin on the connector that should show constant voltage is the 12-volt accessory circuit. The pin for the brake output should only show output when the vehicle brakes are applied or the override switch on the brake controller is activated.
If you are getting constant 12-volt output on the 7-way connector, I would first recommend checking that the connector is properly wired, and that the brake output wire was not swapped for the 12-volt accessory circuit.
If the connector checks out fine, take a look at your brake controller. Use a circuit tester, such as part # PTW2993 and test the red wire exiting the rear of the brake controller. Make sure that there is only voltage on this wire when the brake is pressed.
Test the blue wire, there should be no output unless you activate the manual override switch.

expert reply by: Mike L