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Trailer Brake/Turn Lights Not Working After Installing Wiring Harness on a 2012 Nissan Frontier


The 118525 wiring kit was installed in this truck that came without a tow package. Everything looks good. I check the wiring and relays behind the kick panel and the wiring harness that plugs into the factory plug. I have running lights but do not have blinkers or brake lights. Any help would appreciate any help or advise

Expert Reply:

There are some Nissan vehicles that require an additional relay from a Nissan dealer to make everything fully functional. However if you have found all the relays in the proper places and have installed the relays in wiring harness # 118525 as indicated in the instructions, linked for referenced, and like in the video I have included then there could a problem in a different location.

Use a circuit tester like # 3808 if you do not already have one to test the 4-Way end of the harness without the trailer connected. Have someone run through each function (running lights, brake, turn signals) while you test the pins on the 4-Way. If all of the signals are coming through on the 4-Way then that indicates a problem on the trailer.

If the signals are not coming through on the 4-Way then there could be a wiring problem on the vehicle or something was not installed quite right.

To test the trailer you will want to first make sure that all of the pins on the trailer connector are clean and free of corrosion. next make sure the main trailer connector ground is attached to a clean and corrosion free bare metal surface. Do the same from the ground connections at each of the trailer lights.

I have included a link to our trailer wiring FAQ that also might be helpful.

expert reply by:
Michael H

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