Troubleshooting Trailer Running Lights Not Active 2025 Nissan Frontier

Question

Question:

We have a 2025 Nissan Frontier SV without factory trailer wiring, the newest in our fleet of 6 tow vehicles and 3 trailers. Using your wiring harness item 118266 does not activate the running lights brake lights and indicators work. All tow vehicles have RV 7-way plugs we use a 7-pin to 4-pin converter because none of the current trailers have electric brakes. All lights of all trailers work properly all tow vehicles, except now the Nissan. What is the problem / resolution?

asked by: Edwin

0

Expert Reply:

Hey Edwin, this is a known issue with certain Nissan models. A lot of times there will be some wiring already in place but no relays. The Tekonsha # 118266 comes with the necessary relays as well as the 7-way plug but sometimes there still is a missing relay for the running light circuit.

The Curt Relay Kit # C57000 would be what you would need for that. You will need to refer to your owners manual for the exact relay location. A lot of times it is behind the passenger side kick panel or under the dash on the left of the steering wheel.

expert reply by: Jameson C

0

Edwin

12/12/2025

Thanks for your help. Turns out the error was on me. The paper instructions for the wiring kit 118266 were not clear, or I did not read it thoroughly. I installed the hitch and hooked up the wiring to the truck at the back, but stopped there. My day-time testing showed that stop and turn signals work so I considered the job done. I thought the other wire harness and the 3 relays were for a brake controller and charging the battery in dual axle trailers with electric brakes, which I don't need. I even labeled the package "brake controller for Nissan" and shoved it in a drawer to revisit in case of future ownership of a dual axle trailer. A few months later when using a trailer at night, I realized the running lights didn't work, hence me reaching out here. Your comment "...# 118266 comes with the necessary relays..." was key. I found that harness and relays. My lights came on. Connecting it to the Nissan's wiring at the passenger-size footwell was a breeze, and now the trailers' lights come on too.

Jameson C.

12/15/2025

@Edwin Glad you got it figured out and didn't have to buy anything else! Those are the best solutions haha.

Answer 1

This is a very common issue with newer Nissan vehicles like your 2019 Nissan Frontier. There is a missing relay needed to activate the trailer running light circuit. The running light relay can be installed or replaced with #C57000. One likely place…

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Answer 2

The Nissan vehicles like your Frontier use relays to control the stop/turn signal circuits. Under the hood of your truck there will be a few blue relays in a box on the passenger side near the firewall. See picture. Use the diagram on the top of the…

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Answer 3

Based on my research, in your 2007 Nissan Titan the 10-amp fuse for taillights is located in the IPDM, which is behind the power distribution box in a separate enclosure (closer to the passenger). The IPDM, or Intelligent Power Distribution module,…

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Answer 4

On certain Nissan vehicles like yours an additional blue relay is sometimes needed to activate the trailer running lights circuit. This appears to be the case with your 2018 Nissan Frontier since this circuit isn't active. This is a very common…

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Answer 5

This is actually a fairly common issue with certain Nissan vehicles but it should be a simple fix. It sounds like the relay for the trailer running light circuit is either missing or needs to be replaced. This relay should be located behind the…

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Answer 6

Trailer running lights not working with certain Nissan vehicles is a common problem with an easy fix. There is a relay for the trailer running light circuit that is located in the fuse box (in the cab). If that relay is missing or no longer functions…

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Answer 7

Are there still open spots on the fuse panel? A lot of times there will be 1 brown relay that activates the 12v power for the trailer connector, and there will be 2 blue relays which are for the turn signals. So even though there are already 3…

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Answer 8

On some Nissan vehicles, including the Frontier, you will need an additional relay if it is not present in the relay harness in the cab of the vehicle. For this relay, you can use one of the blue relays from the Curt Relay KIt #C57000. To access the…

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Answer 9

This is a known issue with certain Nissan models. A lot of times there will be some wiring already in place but no relays. The Tekonsha #118266 comes with the necessary relays as well as the 7-way plug. It sounds like you already have the 7-way plug,…

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Answer 10

Hello Dan, thanks for reaching out. We do offer a wiring harness for your 2025 Nissan Frontier S. We have options for both a 4-flat or a 7-way. What you will need is the following: - T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector…

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Answer 11

Hey Dean, thanks for reaching out! The T-One Kit #118266 and T-One Kit #118281 look to be identical for your 2024 Nissan Frontier so I'm guessing the 118266 is replacing the 118281 for whatever reason. Either one will work for your truck, so…

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Answer 12

In your 2017 Nissan Frontier, the Curt brake controller should be installed using the custom wiring adapter #C51382. This should work correctly to give you the proper wiring within your cab. Then you will use the Curt #C56226 or the Tekonsha #118266…

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Troubleshooting Trailer Running Lights Not Active 2025 Nissan Frontier

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