Brake Controller Wiring Causing Malfunction of Lights on 1999 Ford F-150  

Question:

Expert Reply:

A brake controller should have no affect on the vehicle running lights unless it is wired incorrectly at the trailer connector. I would begin by first disconnecting the battery on your truck since you will be working with the electrical system. Then, you will want to check the fuses on your truck to make they are not bad.

Then, after making sure the fuses were good and testing the lights, remove the brake controller and 7-way connector. To disconnect, unplug the wiring from the 7-way that plugs into the factory wiring harness near the rear of the truck. Next, unplug the brake controller which should plug into the brake controller port underneath the dash. This port should be located to the left of the steering column near the emergency brake pedal.

If the lighting on the vehicle is fine, but the lights on the trailer are not operating correctly, I would start at the vehicle side trailer connector. Make sure there is power to the wires using a circuit tester, part # PTW2993. If you have power to these wires, the problem may be with the trailer wiring or connector.

If after removing the brake controller and wiring, and verifying that the fuses are good, and you are still having issues with the lights on your truck, I would recommend having the truck checked out by your Ford Dealership. There may be a short in the vehicle wiring somewhere.

I have linked a video installation of a brake controller on a 2001 Ford F-150 that shows the locations of these plugs.

expert reply by: Reno H

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