Troubleshooting A 7-Way Trailer Wiring Harness That Isn't Sending Braking And Turning Signals

Published 01/12/2022

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Dielectric Grease for Electrical Connectors, 2 oz.

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LCD Digital Circuit Tester

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Question:

I just installed the T-One Vehicle Wiring Harness with 7-Way Trailer Connector on my 2007 Nissan Fontier SE 4x4. The trailer tail lights worked fine BUT no brake or turn signals will work. I did hook the trailer to my Chev Tahoe after trying it and everything worked fine. Any suggestions

asked by: Benjamin B

Expert Reply:

Since the T-One Vehicle Wiring Harness with 7-Way Trailer Connector # 118281 is a quick plug and play style connection I would first check the pins in each connector and ensure none are bent, missing, and that there isn't any debris blocking the connections. You can use some Dielectric Grease # 11755 to ensure a proper and waterproof connection.

Next you can test the pins at the 7-way using a tester like the # PTW2992 to see if the signal is being sent or is getting lost somewhere before the 7-way. I've attached a color coding guide below that will help you test each function.

Since you stated the trailer worked fine hooked up to your other vehicle then that leads me to believe the issue lies with the wiring harness, specifically the portion of the harness connecting the 7-way to your vehicle's wiring. If all connections are good and you're not receiving the signal at the 7-way then the harness itself is faulty and will need to be replaced.

expert reply by: Kevin C