Troubleshooting Trailer Running Lights Not Functioning with a 2013 Nissan Frontier

Question:

Any ideas as to why the trailer lights arent working but turn signals and brake lights are?

asked by: Chris P

Expert Reply:

First we need to determine if the problem is on the trailer or the tow vehicle side of the wiring equation. To do that you will need to use a circuit tester like the part # PTW2993 that you referenced to test the circuits of your trailer wiring harness to see if voltage is on the correct circuits at the correct time. Check out the video I attached to see how this is done.

If you determine the problem is on your 2013 Nissan Frontier I would almost guarantee the issue is a blown fuse. You will need to check fuse box legends for a fuse or relay labeled trailer running lights and replace as necessary.

On trailers, the ground is usually through the mounting studs. If there is any dirt or corrosion, it could cause a bad ground. You will also need to check the ground from the lights to the connector. I have included a video on the procedure for testing a ground below.

If the grounds check out, you will have to test the wiring at various points from the plug all the way back to the lights to make sure the lights are receiving power.

If your trailer has a lot of lights on it (marker lights on the side for example) the power draw might be too much for the wiring to handle. If this is the case, you would need a powered converter that connects directly to the battery to power the lights.

expert reply by: Jameson C