Troubleshooting Trailer Running Light Circuit of 2018 Nissan Frontier Not Active

Question:

The plug for the single blue relay is not behind the kick panel, or by the steering column.

asked by: Walter J

Helpful Expert Reply:

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 issue surprisingly.

For the relay by itself you can use part # 38666-1 and the harness you need to access to plug the relay in is indeed located in the cab behind the panel to the right of the passenger's foot panel.

It sometimes can be located under the dash behind a panel there too.

expert reply by: Jameson C

click to enlarge

Walter J.

2/21/2020

Do I need that harness that plugs in behind the kick panel in the video? I have the flat 4 already plugged into the plug on the frame for the trailer. Thankyou

Jameson C.

2/21/2020

It should be there already. All you'd need is the relay.

Walter J.

3/2/2020

I dont have the whole harness that plugs into the factory plug behind the kick panel. I only have the blue relay for the park/ running lights. There is no place behind the kick panel for just the blue relay in the video, or truck. I looked, and it only has the big plug for the harness that you plug into for all the relays. Do you know where just the blue relay goes for the park lights?

Jameson C.

3/2/2020

That would mean the harness you need is behind the dash panel to the left of the steering column instead. I attached a second picture that shows where it is.