Troubleshooting Running Light Circuit of Trailer Towed by 1999 Nissan Frontier

Question:

I have a 1999 nissian frontier xe and my park lights dont work..fuses ok and bulbs ok whats wrong?

asked by: Joe

Expert Reply:

I'm assuming you mean the parking lights on your trailer, and that you're using an aftermarket wiring harness like part # 118362. The most likely culprit is a shorted-out converter box on your trailer wiring harness.

To begin troubleshooting, you'll need to determine if the problem exists in the trailer wiring or with the wiring on the vehicle. With the truck running lights switched on, test the pin on the trailer connector that's fed by the brown wire, using a circuit tester like part # PTW2993. If you're not getting a signal on that pin, check the brown wire on the other side of the converter. If you have power entering the converter box on the brown wire, but not exiting it, the converter is blown and would need to be replaced. Before replacing the converter, you'll need to closely examine the running light circuit on the trailer, looking for the short circuit that caused the converter to blow. Look for pinched wires or any wiring insulation that's worn away or cracked that would allow the copper conductor to short out on the trailer frame.

Once you repair the short, you can replace the wiring harness/converter. If the converter tests out okay, get back with me and we'll look into some other options.

expert reply by: Mike L