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  1. Custom Fit Vehicle Wiring
  2. Tekonsha
  3. Custom Fit
  4. Trailer Hitch Wiring
  5. 4 Flat
  6. No Converter
T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

Item # 118525
Our Price: $54.91
You Save: 37%
Custom Fit Vehicle Wiring

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Tekonsha Custom Fit Vehicle Wiring - 118525
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Quickly and easily install a 4-way trailer connector on your vehicle with this custom wiring harness. T-One connector plugs directly into existing wiring - no cutting, splicing or tapping required. 1-833-496-1390 to order Tekonsha custom fit vehicle wiring part number 118525 or order online at Free expert support on all Tekonsha products. Great prices and Fastest Shipping for T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.
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  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118525

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • No Converter
  • Tekonsha

Quickly and easily install a 4-way trailer connector on your vehicle with this custom wiring harness. T-One connector plugs directly into existing wiring - no cutting, splicing or tapping required.


  • Provides a 4-way flat trailer connector at the back of your vehicle to power your trailer's signal lights
    • Compatible with 5-pole, 6-pole and 7-pole adapters (sold separately)
  • Connects quickly and easily - no cutting or splicing of wires
    • Locate connection point along frame rail
    • Plug in connector
  • Includes required relays to activate functions
  • Constructed of 16-gauge bonded wire
  • Comes with dust cap for 4-way flat connector


  • Maximum amperage: 7.5 amps per circuit
  • 1-Year limited warranty


This custom-fit T-One connector plugs into your vehicle's wiring harness, which is located beneath the rear of the vehicle, along the driver's-side frame rail. Once you've plugged in the tow harness, connect the included jumper harness with relays to activate functions. This harness plugs into the 12-pin plug that is located behind the passenger's-side kick panel in your cab.

Once installation is complete, the 4-way flat connector will be stowed beneath your vehicle, near the trailer hitch. A mounting bracket (sold separately) is recommended to keep the connector secure.

It is recommended that you use a small amount of grease on all electrical connections - the plugs on your automobile and the 4-pole connector itself - to help prevent corrosion.

118525 Tow Ready T-1 T-Connector - 4 Wire

Installation Details 118525 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Satisfaction Score:

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118525

Average Customer Rating:  4.9 out of 5 stars   (828 Customer Reviews)

Quickly and easily install a 4-way trailer connector on your vehicle with this custom wiring harness. T-One connector plugs directly into existing wiring - no cutting, splicing or tapping required.

Nissan Frontier

Bought a new 2022 Nissan Frontier P/U for my wife and it did not have a towing package and I asked the Nissan dealer to install a 4 pole flat trailer connector upon the purchase of the truck. The dealer said it would be 2 months before they could get an OEM connector from Nissan and I told them to get an after market connector and they would not do that as they stated it could create warranty issues. So, I purchased the wiring harness from etrailer and with the easy to follow instructions, I installed it myself in just a few minutes and it has worked perfectly for a year now. The Nissan dealer wanted almost $[XX] to add the wiring harness and I bought it from etailer for $[XX] and saved a lot of money. Thanks etrailer for providing equipment that saves your customers a lot of money.


The hitch litterally installed in approximately 20 minutes. Perfect fit. The wiring harness probably took about a hour, also perfect. Just plug and play.All items appear to be excellent quality. etrailer customer service is also EXCELLENT. All reps that I spoke with were extremely polite, knowledgeable, and they really listen when you speak. Other businesses need to take note of what real customer service is really like. Thank you etrailer!


The only thing that happened I paid 18.00 to expedite my shipment was UPS does not run on weekends and my shipment arrived in Sylva NC on Saturday, October 22nd and stayed there until it was delivered on Monday October 24th That is the only thing that happened. The wiring harness worked great


Big thumbs up to etrailer for a great price and prompt delivery of the hitch and wiring harness kit for my new ‘22 Frontier. Also kudos for their excellent instructional installation video posted on the website. I did the install alone and it was done in less than an hour including testing (would’ve taken less time if the main relay connection behind the kick panel in my Frontier hadn’t been taped to a harness and hard to find).


I bought this hitch and wiring for a new 2019 Nissan Frontier.
I installed everything myself. The receiver would be easier to install with a second pair of hands but I managed by using a piece of rope to lift one side into place and kept it suspended so I could get the bolts started in the other side. Then started the bolts in the rope side and tighten them up and done. No need to remove the spare tire or anything else. Just lift it up and put the bolts in. Be sure to put a torque wrench on them because the recommend foot pounds is probably tighter than what you would guess just going by feel.
I was intimidated by the wiring, going under the kick panel and everything. It turned out to be super easy. I mean like 5 minutes and you are done. Total plug and play. Watch the videos and you can't go wrong. It couldn't get much easier than this unless you have someone else do it.


this wiring harness was the most complete kits I've ever seen. it came with detailed instructions and everything I needed for installation.


This harness was easy to install and works like it is supposed to.

2018 Nissan Frontier

Box was destroyed, sent pictures yesterday. Trailer hitch is scratched up and gouged. Box was not thick enough for such a heavy item

Thank you for letting us know! I have sent this information along to our customer service team. They will be in contact shortly.
-- Etrailer Expert Brooke M - 07/26/2022

2022 Nissan Frontier

I think there should be an option to order just the part you need for this specific truck. 2022 Nissan Frontier. For $XX you only need 1 part of this kit and plug it into the wiring harness on the truck. Seems to me you should be able to buy this separate from All the extra parts in the box. Pretty pricey for a 3-4 foot piece of wire for lights.


product worked great, easy to install. Wire harness was also very easy to install for trailer towing

Nissan Frontier

Easy to install and works great. On a 2022 Nissan Frontier If you are looking for the wiring harness in the kick plate it is wrapped in grey tape towards outside of the truck on the passenger side. The wiring kit was super easy to install just plugs right in.

2022 Nissan Frontier

The hitch receiver and harness kit came together in the same box. Arrived in great shape. I read a few reviews how their hitch receiver arrived damaged/bent. Mine did not, it was pristine. No issues whatsoever installing them on my 2022 Nissan Frontier by myself. 3/4" socket and less than 20 minutes. The longest part of my installation was finding and digging out my extender for my drive to tighten down the one bolt thats partially tucked behind the exhaust pipe. 100% satisfaction but did use two additional zip ties for the rear wiring in the harness kit.


The harness was extremely easy to install. When connecting my truck to the utility trailer all lights brake, hazard lights & running lights worked as expected.

2010 Nissan Frontier

I am very impressed with this wiring harness. I own a 2022 Nissan Frontier that came wired for trailer, I bought a utility trailer hooked it up and had brake and turn but no tail or marker lights, what's wrong after searching the internet for others that might have had this problem discovered that I needed this harness read and watched videos on how to install the harness and ordered one to my surprise the install was simpler than I thought it only took about 10 minutes and now I have tail and marker lights. Great product, fast shipping and great how-to videos. Thanks, I can now pull my trailer at night.

2011 Nissan Frontier

just got my wiring harness yesterday was easy to install just like the video they have posted on their website really easy took me about 15 minutes to install had no issues installing

Good have had no issues
Nelson M - 09/15/2015


Etrailer was great to deal with I will use them again !

2010 Nissan Xterra

I totally bought from etrailer because of all the "How To Install" videos. I bought hitch #13514 and light kit #118525 both from etrailer. Install could be a one-person job, but I would recommend two-person. Installed hitch and light kit in about an hour with two-people. After install I added a self-adhesive Diamond designed rubber matt on the hitch step, this avoided any foot slips. I bought the rubber matt from Harbor Freight. I think etailer should make this an enhancement to the hitch. I also used velcro straps to keep wiring tucked away until needed, also purchased from Harbor Frieght. Both hitch and light kit are very well made, not cheaply made. I am very satisfied with the product.


The prodict is aweseom. The instructions were legible and to the point, I had it installed in a little over 30 minutes

2009 Nissan Frontier

The trailer wiring harness was delivered in the specified timeframe. Didn’t take long to install. On both this order as well as a recent order (receiver hitch) the price was the lowest I found. I’m very satisfied with my experiences with etrailers.

2019 Nissan Frontier

Great video for installation, convenient product, received two days before due date. Highly recommended!

2022 Nissan Frontier

I had a hitch and wiring installed locally and the installer couldn't get the lights to work. A few minutes on the etrailer site and I had a pretty good guess what was wrong. One look inside the truck and my guess that the relays and harness hadn't been installed was correct. I ordered it and with the online video, was able to get it installed and everything was up and running in about 15 minutes. The only hard part was getting the kick panel back in place on the truck.

2015 Nissan Xterra

My eTrailer purchase experience has been fantastic! Quality products, low prices, fast shipping, and great instructional videos. The Curt Trailer Hitch (#13514) is definitely a high quality product; I installed it on my 2012 Nissan Xterra PRO-4X. The fit was definitely tight. Not only did I have to remove the rear exhaust hanger per the instructions, I had to remove the mid-hanger just behind the muffler and loosen the hanger just in front on the muffler to get the required clearance. After that it just needed some friendly persuasion; i.e. a hammer. The hitch fits well, looks great, and only took about an hour to install with my 15 year old son. The T-One Vehicle Wiring Harness with Relays (#118525) could not have been easier! I was only cautious of removing the passenger side floor sill and kick panel without a panel puller. Just took my time and didn't rush; panel puller really not required. Had the Xterra wired in 20 minutes. GREAT EXPERIENCE WITH eTrailer! They have gained a repeat customer!!!

2012 Suzuki Equator

Easy install good quality

Working great
Jeffrey - 11/13/2022


Received the hitch and wiring assembly yesterday, the order actually arrived earlier than the expected date. It was ever thing I expected and more, great quality product. Installation was easy, everything lined up exactly. I did this by myself with the help of a jack. The wiring kit that I bought was a very simple, watched the video a couple of times and everything went according to the instructions. I would recommend this product to a friend. I save myself about $250 by doing this myself and ordering from etrailer


Instructions were clear. It was easy to install. Price was very reasonable.

Show More Reviews

See what our Experts say about this Tekonsha Custom Fit Vehicle Wiring

  • Installation of Trailer Wiring Harness on a 2010 Nissan Xterra
    Step 4 in the instructions for wiring harness # 118525, linked for reference, seems to be where you are running into a little trouble. Before plugging in the harness to the vehicle behind that kick panel, you will need to insert the relays on the the connector. On the other end of the 12 pin connector there are 3 ports, one for each of the relays. The brown one goes with the brown relay and the white plugs go with the blue relays. After you have plugged in everything you can tuck in the...
    view full answer...
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  • Where do the Relays of the Tow Ready Custom Fit Wiring # 118525 Install on a 2006 Nissan Frontier
    The relays and the jumper plug will install under the passenger side kick plate of your 2006 Nissan Frontier. Check out the installation instructions and video I attached for this product.
    view full answer...
  • Trailer Wiring Harness for a 2010 Nissan Xterra without Factory Tow Package
    It sounds like you need the relay for the running light circuit to function on your 2010 Nissan Xterra. Wiring harness # 118525 comes with 3 relays to make the harness fully functional. This harness is designed specifically if the vehicle did not come with the factory tow package.
    view full answer...
  • Trailer Lights Back Feed to 2008 Nissan Xterra with Unknown Wiring Harness Installed
    It is entirely possible that the wrong wiring harness was installed or a harness was incorrectly installed on your 2008 Nissan Xterra. There may also be a ground problem somewhere. If your Xterra did not come with a factory tow package then you would need to install harness # 118525 that you have referenced which comes with relays to activate the harness. On some vehicles, an additional relay is needed in the in-cab fuse panel. This relay can be obtained from the dealer. It sounds like...
    view full answer...
  • What Circuits do the Relays in the Tow Ready Harness # 118525 Activate
    The large brown relay activates the 12 volt power circuit and the blue relays power the turn signal circuits. The brown relay may not be needed for you since you the T-One Vehicle Wiring Harness # 118525 that you referenced has a 4-way and does not necessarily need this circuit activated. Your dealer may have already installed the relays and that would explain why it does not seem like you do not need them.
    view full answer...
  • Installation of Tow Ready Trailer Wiring Harness # 118525 on 2012 Nissan Pathfinder
    Although we have not yet had the opportunity to install the # 118525 trailer wiring harness on a 2012 Pathfinder, my contact at Tow Ready tells me that the only difference in the installation between the Pathfinder, Xterra and Frontier is the location of the connector at the rear of the vehicle that the 4-pole connector would plug into. The procedure for installing the remainder of the harness and the relays behind the kick panel in the passenger side front seat foot well is exactly the...
    view full answer...
    Image 1 for
  • Trailer Wiring Harness for a 2006 Nissan Xterra without Factory Tow Package
    For a 2006 Nissan Xterra you can use wiring harness # 118525 that you have referenced. This is the correct harness for an Xterra that did NOT come with a factory 4-Way or 7-Way trailer connector. I have included a link to a video showing a typical installation and a link to the installation instructions.
    view full answer...
  • Trailer Running Light Circuit Does Not Work On 2006 Nissan Xterra 4-Way Trailer Wiring Harness
    You are most likely missing one relay or fuse to control the running lights. Use the vehicle owners manual to find the locations of the relays/fuses associated with the trailer wiring. The one that is for the running lights could be missing or it could have gone bad. It is also possible that there is another relay required in the in-cab fuse panel that you will need to obtain from the dealer.
    view full answer...
  • Trailer Running Lights are Not Working on Trailer Towed by a 2009 Nissan Xterra
    If your 2009 Nissan Xterra did not come with a factory tow package, you would need to have the appropriate relays in addition to a wiring harness in order for all of the trailer lights to work properly. The harness that you have referenced, # 118525, does come with the relays needed to make the trailer wiring harness fully functional. I have included a link to the installation details for you. If your Xterra came with a tow package you can check to see if the relays are there and functioning....
    view full answer...
  • Troubleshooting Trailer Lights After Installing Wiring in 2006 Nissan Xterra
    Thank you for your recent purchase from etrailer and for detailing your troubleshooting efforts with your wiring harness kit # 118525. Since you have applied a circuit tester to the 4-pole harness and confirmed that it has the correct output, and that it works fine with a second trailer, odds are that your issue is within the wiring on the first trailer. It is possible for corrosion to build up inside the connectors or on their contact surfaces. Even slight greenish or whitish discoloration...
    view full answer...
  • Cannot Find 12 Pin Connector Behind Kick Panel to Install Wiring Harness on a 2007 Nissan Frontier
    From there you will want to look behind the passenger's side kick panel (right side front) because that is the location of the factory harness on your 2007 Nissan Frontier to install # 118525. If that is where you are looking (and we are just calling it different things) then it is possible that the harness has fallen down, is tucked up higher, or is otherwise hidden.
    view full answer...
  • Wiring Harness for Towing a Trailer with a 2011 Nissan Xterra Pro 4 X
    Since you don't currently have a 4-way trailer connector on your 2011 Nissan Xterra Pro 4 X you can use the Tekonsha # 118525 wiring harness. It includes all of the jumpers and relays you'll need to activate the tow package. I've linked an install video for you.
    view full answer...
  • Recommend T-One Harness # 118525 for 2012 Nissan Frontier
    The relays you need for your 2012 Nissan Frontier are part # C57000. This relay kit includes the large brown relay which activates the 12-volt power circuit, and the smaller blue relays which activate the turn signals. I have linked you to the Installation video for this kit.
    view full answer...
  • Trailer Wiring Recommendation for a 2014 Nissan Frontier
    In your case it sounds like your 1999 Nissan Frontier already had the relays installed. So for you no, it would not be necessary to use the included relays. If the vehicle has a tow package most likely the relays are already in place. If you install everything but the relays and it all works then you would be good-to-go on your 2014 Nissan Frontier. If not, then you would need to install them. The large brown relay is for the 12-volt power source for a 7-way and the blue relays are for...
    view full answer...
  • Trailer Wiring Recommendation and Install Video for a 2012 Nissan Xterra
    The connector can be hidden behind the other connectors and wires and hard to see. There is a connector that looks similar that is already used, but it is not the correct connector. The connector they need should be toward the top, possibly tucked behind other wires and connectors. Or there may be an incomplete or complete harness with relays plugged in on your 2012 Nissan Xterra. What you could do is just plug in the rest of the harness and see the 4-way works. If it does then you're...
    view full answer...
  • Wiring Harness for 2006 Nissan Frontier
    Tow Ready offers the T-One Vehicle Wiring Harness, # 118525, for your 2006 Nissan Frontier. This plug-in wiring harness provides a 4-way flat trailer connector at the back of your Frontier to power your trailer's signal lights with no cutting or splicing required. I have attached an installation video that you may find helpful.
    view full answer...
  • Finding Relays on 2012 Nissan Frontier for Trailer Running Light Circuit Activation
    The issue is definitely going to be fixed once we can find the running light relay location on your 2012 Nissan Frontier. Did you check the relay location behind the dash panel like in the picture I attached? That's the other really common area for missing relays on Nissans like yours.
    view full answer...
    Image 1 for
  • Only Running Lights Working after Installing Tekonsha T-One Wiring Harness on 2011 Nissan Xterra
    It sounds like everything was installed correctly with the wiring harness # 118525 on your 2011 Nissan Xterra. I recommend first checking to make sure there is no dirt or corrosion on or inside the factory gray connector under your vehicle. Look for anything that might be preventing a clean connection with the wiring harness plug and simply clean it out. A weak connection can certainly lead to the running lights working on your Nissan but nothing else. Also make sure that the harness...
    view full answer...
  • Troubleshooting Left Turn and Brake Light Not Working on 2005 Nissan Frontier with Tow Package
    First make sure the truck's trailer connector is clean and free of any corrosion. Then you'll want to check the fuses and towing relays. Check your owner's manual to find the correct ones. There are relays needed to activate the tow package that are included in the harnesses we sell like # 118525. I've linked a video of the harness being installed that may be helpful for locating the relays.
    view full answer...
  • Troubleshooting a 2012 Nissan Xterra That Only the Left Blinker Functions
    Sounds like you have eliminated the trailer as being the problem since a different vehicle operated the trailer lights just fine. I would start by checking the fuses/relays of your 2012 Nissan Xterra as that would be the most likely reason for your issues. Check the vehicle owners manual for the fuse and relay locations. The correct replacement relays you would need would be the part # 38666-1 if you determine they are blown. These fuses and relays typically go out when there is a short...
    view full answer...
  • Where does the Connector of the Tow Ready Harness part # 118525 Install on a 2014 Nissan Frontier
    If the connector you found on your 2014 Nissan Frontier has a red and a green wire coming out of it it sounds like you haven't found the correct connector yet. The correct one can be a little hard to find but it won't have any wires coming out of the front of it. Check out the video I attached that shows the Tow Ready Harness part # 118525 being installed in a similar Frontier as yours.
    view full answer...
  • Availability of Plug-in Trailer Wiring Harness without Factory Tow Package on 2014 Nissan Xterra
    For a 2014 Nissan Xterra you can use wiring harness # 118525, which you have referenced. This is the correct harness for an Xterra that did not come with a factory 4-Way or 7-Way trailer connector. The relays will be needed for the activation of the trailer wiring. I have included a link to a video showing a typical installation and a link to the installation instructions.
    view full answer...
  • Trailer Wiring Harness For 2015 Nissan Frontier Pickup
    The Tow Ready T-One Vehicle Wiring Harness, part # 118525 is confirmed as a fit for your 2015 Frontier. To install the harness you will need to access the connectors on the passenger side to install the included relays. It requires removing the passenger side threshold and the panel on the side of the vehicle. You will also need to find the connector under the vehicle on the driver side by the spare tire for the harness to plug into. I have attached a link to an installation video you...
    view full answer...
  • Troubleshooting Trailer Wiring that Left Stop/Turn is Dim
    Since the trailer wiring on the vehicle has checked out with a tester it would seem that the problem is actually on the trailer. It sounds like you are experiencing a ground problem. Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces. The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything...
    view full answer...

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