Troubleshooting No Turn Signals on Trailer Towed by 2015 Nissan Frontier  

Question:

Expert Reply:

If the factory 4-pole trailer wiring on your 2015 Nissan Frontier is not providing turn signals the issue could have several causes.

It is possible the factory/dealership did not install the required relays in the Frontier. We offer the relays by themselves as part # C57000 and as part of a complete wiring harness kit # C56225. You could also have a blown fuse in the power distribution box; this you can check by taking off the lid and finding the fuses related to trailer lights. Check and replace as needed.

Another potential cause is simple corrosion on the connectors. If you have a circuit tester like # PTW2993 you can test the vehicle's connector to see if the lighting signals are reaching all the way to the back of the Frontier. If so, then check for discoloration and corrosion on the trailer's connector.

You can also test the trailer lights directly, without it connected to the Frontier. Just apply 12V power from any vehicle (or spare 12V) battery directly to the pins on the trailer's connector to see if the lighting functions work. If the lights work when connected this way you know the issue is on the vehicle side. If the lights do not work when directly connected then you need to further troubleshooting the wiring on the trailer.

Trace the wiring from the connector all the way along the trailer frame, checking for worn or cracked insulation especially at points where the wires have to bend sharply or where they may contact the trailer frame. Repair or replace any damaged wire as needed.

Another thing you can check is that the main white ground wires on both the vehicle harness and the trailer are solidly connected to clean bare metal surfaces.

An article on troubleshooting wiring is linked for you too.

expert reply by: Adam R

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