Troubleshooting Trailer Running Lamp Circuit

Question:

Me and my grandfather have just hooked up a 7way connector to our trailer and everything is running except the running lights. We have made sure everything has been hooked up correctly but we have no Running lights. Any advice would help. Thank You

asked by: Carlos

Expert Reply:

The first thing I'd do is check the running lamp pin on the 7-way on the vehicle. When you're looking at the connector the pin for the running light circuit would be in the 11:00 position on the connector. With the truck's headlights on, use a circuit tester like part # PTW2993 to test that pin. If there's power on the pin, the problem is in the running light circuit on the trailer. If there is no power on the pin, the problem exists on the vehicle.

If the problems is on the vehicle, how you proceed will depend on if the 7-way was factory installed or aftermarket. If it's factory installed, you'll need to consult your owner's manual to determine where the tow package fuses are located. If the 7-way on the vehicle is aftermarket, you'll need to trace the wires to find where the running lamp circuit connects to the vehicle wiring. Make sure the connection is secure.

If the problem is on the trailer, make sure the running lamp connection is securely made on the socket that mates with the running light pin of the vehicle-side connector. Trace that circuit back to the running lamps, looking for pinched wires, loose connections or broken wires.

I'll link you to our trailer wiring FAQ article and an article that explains how to troubleshoot trailer wiring problems.

expert reply by: Mike L