Troubleshooting a 1999 Ford F250 that Lost Interior Lights, Dash Lights and Running Lights

Question:

Hello All,I have an early 1999 Ford F250SD 7.3PWSTRK. My problem just happened today 9-11-14. I cant figure it out to save my life. I had a professional installation on a four gauge pillar pod setup installed along with a new Primus IQ trailer Brake Control. It was installed that the gauges turn on as soon as the key is turned over and the trailer brake only turns on when the lights are turned on. This afternoon I was adjusting the brake control and used the push slide and all of a sudden, I lost power to my pod gauges my instrument lighting , roof lighting, all trailer connections and my daylight running lights in the rear only. I double checked every fuse inside the cab and under the hood and nothing was blown. I cant find any in-line fuses anywhere. Can someone please help? I cant drive my truck at night without any rear lighting

asked by: Jason

Expert Reply:

Brake controllers draw a considerable amount of amperage. What I can almost guarantee happened is when you hit the override lever of the controller you overdrew the running light/head light circuit you used to power the brake controller. Once you determine what has shorted out on the truck I would strongly recommend you change the wiring of the brake controller so that it is powered straight off of the positive terminal of the battery through a circuit breaker like part # 9506P.

Pull the headlight switch back out and check for voltage on the tan/white wire.

Most likely because of your symptoms, you will find the tan/white wire dead. So follow this wire back and see if it's burnt in two. If it's not, then go back to the fuse and double check for power there.

The tan/white is what feeds the taillamps/running lights and also the dash lights. The power comes right out of the fuse to the tan/white, and the feeds the headlight switch.

The tan/white does not feed the headlights, they have a different power source feeding the headlight switch. What you are doing by pulling the headlight switch out halfway is crossing the contacts inside the switch, so the power for the headlights is jumping over and feeding the running lights circuit, which is supposed to be fed by the tan/white.

expert reply by: Jameson C