Troubleshooting Trailer Brake Controller Circuit on 2010 Nissan Xterra

Question:

wires at rear of vehicle, dont seem to have power for brake controller

asked by: Ann

Expert Reply:

On a vehicle's 7-way trailer socket like # 37185 the power for the trailer's electric brakes is carried on the pin at the 5-o-clock position, as shown in the photo I linked for you. If you have a 7-way and trailer brake controller that have suddenly stopped working, we can help you troubleshoot.

If the controller has power and appears to function normally then the issue could be something as simple as a bit of foreign material, water or corrosion inside the trailer socket on the vehicle. You can inspect the socket for any signs of even slight greenish or whitish discoloration on the contact surface, or even inside the connector, and a simple circuit tester like # PTW2993 will let you test for a signal on that pin. Have a helper press the manual override on the controller, when it is set to full power/boost, to see if that signal reaches the 7-way socket. If not, next apply the tester to the blue wire at the back of the controller and repeat the manual override test.

If you have signal at the 7-way you know the issue is in the wiring between the controller and the trailer socket. If there is no signal at the blue wire at the back of the controller, then the unit is damaged and should be replaced with a quality controller like the popular P2 # 90885.

You can refer to the two linked articles for more help diagnosing the problem.

expert reply by: Adam R