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Trailer Wiring Harness Installation - 2018 Nissan Pathfinder

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How to Install a Trailer Wiring Harness on a 2018 Nissan Pathfinder

Speaker 1: Here on this 2018 Nissan Pathfinder, we're going to be having a look at and showing you how to install the Tekonsha T-One Vehicle Wiring Harness for Factory Tow Package Vehicles with a 7-Way Trailer Connector, part number 118273.Here's what the wiring looks like installed. Now, the reason you're going to want this particular wiring harness for your vehicle is that this is the most versatile option for your Pathfinder. This will give you all the lighting functions that are required by law in order for you to safely and legally tow a trailer in addition to being able to use an electrical trailer brake controller to control electric trailer brakes, provided you have a brake controller installed in your vehicle.One of the things many of our customers have noticed about this wiring harness is that it does come with most everything you need in order to install it with the exception of a mounting bracket to attach it to your vehicle. That's not a big deal. You can pick part number PK12711U on our website at the same time, so you have everything you need in order to get it done properly.This wiring harness does have a nice spring-loaded door here with a gasket inside to help keep the elements out of it. You don't have to worry about any corrosion or dirt buildup inside your connector, so you always have a good electrical connection between your Pathfinder and your trailer.

Now that since this is a 7-way harness and is the most versatile, you can still tow other trailers that have a 6-way connector or a 4-pole flat using adapters, which we have available on our website.One thing that I really like about this wiring harness is that it does come with all the relays and adapters that you need in order to work with your factory tow package wiring. there is no cutting or splicing or any modification required to your vehicle, which could void the warranty on it. This utilizes what your vehicle already has on it from the factory. Now that we've gone over some features, we'll show you how to get it installed.To begin our install, we're going to open our rear hatch. Now, where the carpet from our third row seats meets our storage panel back here, we need to unclip this.

We'll use a trim panel tool for this. You can also use a flathead screwdriver. We'll just get underneath it and we'll pop up these Christmas tree style fasteners. Just feel for them, then pop up. Fold this forward.

Now we'll lift up on the lid for a storage compartment. Now we'll find three 10mm fasteners just like this one here that we need to remove.We'll lift up on our threshold panel here. Once we have it popped loose before we can remove it all the way, underneath our latch right here there's this panel that we need to pop out. We can use our trim panel tool or flathead screwdriver, slide it out from underneath the latch. Then we can grab this panel and lift it all the way out.

We now have access to the four plastic fasteners like this that hold our storage compartment in place,. Use our trim panel tool and just pop up on these. Now we can grab the panel, lift it up on it, and take it out of the vehicle.Now we're going to remove our cargo tie-down points on the drive side of the vehicle. Lift up on the hook, use a flathead screwdriver, pry up on the cover. Underneath that we'll find a 10mm screw. We'll do the same for the other one. We'll unclip this panel by prying up on the two clips. We'll set it aside. Now we'll remove the five 10mm screws and bolts that are just like this one. With our panel unbolted now, we'll unclip the carpet from it by removing the pushpin. We can now grab this bracket and lift it out of the vehicle.Now, on the very far back drive side corner of our hatch area, we'll find two connectors, a black one here and a white one here. This is where our relay harness will plug into. Now we'll take a relay harness here. Here's the plugs that go into the factory connector. This is the larger white one. This is the smaller black one. These only go in one way, so you just need to line it up and push it in place until it clicks into position. Those are both securely clipped into place now.Now, we'll plug our relays into the relay harness. The brown relay will go to the brown connector, only goes in one way so just line it up. We'll push until it clicks. These blue ones will go to the white connector, only go in one way. They're the same relays too, so it doesn't matter which direction you put them. This is our foam tape. This will go around our relays to prevent noise. So we'll peel off the backing and just wrap it around the end of the relays doing the same for all three, and here's what they look like wrapped up in the foam tape. We went ahead and used some of our provided zip ties to secure our wiring and the relay harness up out of the way. We just zip tied it to an existing wiring harness in the vehicle. With all of our connections now made inside the vehicle, we can now reassemble our brackets and panels in the reverse order or removal.Now on the passenger side of our vehicle behind the fascia in this general area here, this is where we're going to locate our connectors for the factory tow package for a 7-way connector. So we look up, we'll find two connectors, a gray one and a black one. Both of these connectors have a dummy plug in it to protect them. We need to remove the dummy plug. I like to use a pair or needle-nose pliers for this, makes it a little bit easier. We can squeeze the tab on the connector and pull down to remove it. This is the tab right here that we squeezed to remove it from the connector. We'll do the same for both of them. This is the tab on our black one.This is our 7-way harness. We have a gray plug and a black plug. These will go in the factory plugs. They only go in one way, so we'll just match them up and push it in until it locks into place. We went ahead and routed the 7-way connector behind our fascia above our hitch around our spare tire, and we secured it to our fascia support bracket here with a zip tie. This will get our 7-way connector right below where we're going to mount it on our vehicle.This is our 7-way connector. We need to have a way to attach this to our vehicle. We'll be utilizing the 7-way mounting bracket. This will attach to our hitch, which has a welded-on flange for mounting any electrical connectors. We'll attach our 7-way to the bracket using the provided hardware that came with the bracket. Now we'll attach the 7-way to our hitch. Now we'll securely tighten our bracket to our hitch. Now we'll take some dialectric grease, which we have available on our website, and put it inside of our connector. This will help prevent any corrosion from occurring if any moisture was to get inside. I will now plug this into our 7-way. It only goes in one way, so just line it up and then push securely until it locks into place.Now we're underneath the hood. On the driver side of the vehicle just behind our headlight assembly, we'll find one of our fuse boxes right here. We need to double check and make sure there are relays in place. Open this up and pulling back on the tab and lifting up, and as we see, we do see two blue relays in place from the factory on our vehicle. If we don't have those installed, our kit does come with two additional relays to put in those places.Now we have a tester plugged into our 7-way. We're going to test out all of our functions to make sure everything's working properly. We'll start off by checking and see if we have constant 12-volt power. As you can see from this gauge here, we do, so that means our 12-volt power is working on our 7-way. Now we'll run through all of our lighting functions and test those out.I'll start off by turning on our headlights, and as you can see, our clearance light and tail light function on our trailer will be working. Now I'll do a left turn signal, that works. I'll do a right, that works. Check out our brake lights, those are working. With our foot on the brake pedal, I'll double check and make sure our turn signals still work properly. Left works, right works, and now I'll check out the reverse light function and that works as well too.That completes our look at and showing you how to install the Tekonsha T-One Vehicle Wiring Harness for Factory Tow Package Vehicles with a 7-Way Trailer Connector, part number 118273, on this 2018 Nissan Pathfinder.

Armando M.


Hi ,I have a question. After installing the harness, I connected an adapter from the 7 way to a 5 pole flat . My trailer lights are not working.any suggestions on what could be wrong?? I followed all steps on the video. Thanks.

Etrailer Expert

Jon G.


The first step to take is to test both your vehicle and your trailer independently of each other. Use a circuit tester to check all of the functions on your vehicle-side 7-Way to make sure that they are all in good-working order, and then apply 12V power to the various pins on your trailer to make sure that everything is good to go (you can also try plugging the trailer into a different vehicle). If both sides look good then the issue is probably your adapter. I am linking an article on troubleshooting wiring and what the various functions on the pins should be for you to check out.

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