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Which is the Correct 7-Way Trailer Wiring Harness for a 2018 Nissan Pathfinder


I installed the T-One wiring harness with 4 pole flat connector 118670 on my 2018 Nissan Pathfinder S and it worked perfectly. I already had the relays under the hood so I did not need them. I then decided to add a 7 way connector so I ordered the replacement wiring harness 118267. I ordered an adapter to step the 7 way down to a 4 way when I needed a 4 way. I installed the replacement harness 118267 and checked it with a multi-meter and with the step down adapter I ordered which has indicator lights. Nothing worked. I took off the replacement harness and put the 4 way harness back on and all of the functions worked. I then took the 4 way harness back off and using a multi-meter, I checked for continuity and mapped which contact on the 4 way gray plug was wired to each contact on the 4 way flat. I then did the same with the gray plug on the 7 way harness. I knew the 4 way was working so I expected the contacts on the 7 way gray plug to map to the same functions as the 4 way. I found that the contact on the 4 way which powers the stop/right turn signal was connected to the ground on the 7 way, the contact on the 4 way which connects to the stop/left turn signal is connected to the stop/right turn signal on the 7 way and the stop/left turn signal on the 7 way is connected to a contact that is not used on the 4 way gray plug. The 7 way replacement harness is supposed to be a replacement for a Nissan Pathfinder but it seems to be wired wrong. Am I missing something?


Expert Reply:

It definitely sounds like you have experience dealing with at least some aspect of wiring as you are taking all of the correct steps to try and remedy the situation. I have a few things for you to check but for starters, I see that you are using the Replacement Wiring Harness for Tow Ready Nissan Vehicle Wiring Harness part # 118267 which is part of the T-One Vehicle Wiring Harness with 7-Way Trailer Connector part # 118266. The problem is that these wiring harnesses are listed as a fit for a 2005 - 2012 Nissan Pathfinder. The correct 7-way trailer wiring harness we have listed for a 2018 model is the T-One Vehicle Wiring Harness part # 118273. I checked this with Tekonsha as well.

So the first thing I must recommend you do is switch to the T-One Vehicle Wiring Harness part # 118273 as although it could look very similar to the T-One Vehicle Wiring Harness with 7-Way Trailer Connector part # 118266, they could be wired completely differently.

A few other things you could check is to try testing the pins on the 7-way trailer wiring harness without the adapter. The adapter could be wired incorrectly so this is something you need to rule out as well. It would be best to test the pins on the end of the 7-way with an actual circuit tester. Also, there are different fuses for both the 4 and 7-way trailers connectors so you will need to make sure the correct 7-way fuses are installed.

expert reply by:
Conner L

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