Troubleshooting 2009 Nissan Frontier4-Pole Trailer Wiring Harness That Wont Operate Trailer Lights

Question:

I have a nissan frontier 2009 without the tow package. I added the #118263 harness and the trailer lights worked great until recently. now I have head/tail lights but no left or right turn signals and no break lights. I have checked the harness and the rear plug for the trailer pigtail has only juice from the head/tail lights no brakes or turn signals. the under dash wire harness SEEMS to be ok. all lights on the truck body work just fine. are there fuses or breakers that would cause this?

asked by: Bill

Expert Reply:

Most likely, your problem is caused by a blown fuse or relay caused by a short in your trailer wiring. First, make sure that the wiring harness that holds the relays behind the passenger side kick panel is plugged in all the way, until it clicks. Make sure the 2 blue relays are fully seated in the harness. You can see the location of the harness by clicking the provided link for the # C56225 wiring harness. You can also check the point where the # 118263 plugs in under the vehicle, making that connection is snug and not corroded.

I looked at an online copy of the owner's manual for the 2009 Frontier, trying to find a fuse diagram. You'll need to consult your copy, to see if you can find any towing-related fuses in the fuse box. Replace any that are blown.

Before plugging your trailer back into the vehicle, give the trailer wiring a full going over. You're looking for pinched wires, or any wire insulation that might have cracked or had the insulation worn off, allowing the copper conductor to short out on the trailer frame.

I'll link you to our trailer wiring troubleshooting article that you might find helpful.

expert reply by: Mike L