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

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

Item # 118722
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Tekonsha Trailer Hitch Wiring - 118722
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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. Powered ModuLite reduces strain on wiring system. Call 800-298-1624 to order Tekonsha custom fit vehicle wiring part number 118722 or order online at etrailer.com. Free expert support on all Tekonsha products. Guaranteed Lowest Price 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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  • Reviews (32235)
  • Q & A (5)
  • Videos (2)
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  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118722

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • Tekonsha
  • Powered Converter

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. Powered ModuLite reduces strain on wiring system.


  • 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
    • Locate connection points behind tail lights
    • Plug in T-connector
    • Connect hot lead to battery
  • Includes ModuLite power module that connects directly to battery to avoid overloading vehicle's electrical system
  • Constructed of 16-gauge bonded wire
  • Comes with dust cap for 4-way flat connector


  • Maximum amperage:
    • Stop/turn lights: 5 amps per circuit
    • Tail lights: 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 behind the driver's-side and passenger's-side tail lights. You will have to remove the tail light assemblies to access this harness.

T-One Connection Location Points Behind Tail Lights

Once you've plugged in the T-connector, run the hot lead up to your car battery. Connect the lead to the included fuse holder, and then connect the fuse holder to the positive terminal on your battery and insert the provided fuse.

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.

ModuLite Powered Tail Light Converter

A ModuLite power module is built into this T-One connector. With a ModuLite, your trailer's lights will be powered without overloading your vehicle's electrical system. Because the module draws power directly from your car's battery and bypasses the electrical routes that are used by a basic wiring harness, there is virtually no draw on your tail light circuits.

118722 Tekonsha T-1 T-Connector - 4 Wire - Modu-Lite Converter Included

Installation Details 118722 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

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

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Trailer Wiring Harness Installation - 2016 Ford Transit T350

Today on our 2016 Ford Transit T-350, we're going to take a look at and show you how to install the Tekonsha T1 vehicle wiring harness with a four pole flat trailer connector. Part number is 118722. To begin our installation we'll open up the rear hatch here and we're going to pull the screw located right here and the one located right here so we can get this housing off of the vehicle. We'll do that with a T-25 Torx bit. Now we want to kind of pull kind of straight back on the light. There's a couple of pressure clips here we need to separate.

And once those are separated we can pull right over this way and here we can see our connector. It's going to be right here at the bottom. It's going to push that tab in, it's located right there. Push that in and slide it off. Okay, we've gained access back there, now we'll prep our wiring harness just by extending out any wires that are bundled up. Put our ground wire down and we'll be attaching that 12 volt power wire roll that we had right to the black wire coming off our box.

So grab our butt connector there, we want to strip back our black wire about a quarter inch or so. Place that on, get that crimped down. And we'll do the same to the black wire off of the box. You need to strip it back just a little bit more than what it is factory just to get a good connection. And once those are crimped, we're going to pull on them to make sure they're nice and solid and we can use a heat source.

That can be a heat gun, it can be a mini torch, or it can be like I've got here just a simple lighter. You can see how that's going to shrink there and we'll know that we've got it done properly because there's going to be a little bit of clear general it'll run out of there. Now we're going to place that underneath a bumper and we want to come out of the small gap that's created right here. And once we have that in position, since we are on a 16 model, there's this little tab right here. We need to get that removed. You can just a razor knife and cut that down so it's flush and then we can slide that into our connector and listen to that little click.

Now while it's not required, if you want to maintain the best looks possible, piece of wire loom. We're going to use the quarter inch, it's available on our website. All you have to do is slide it on there, use a little bit of tape to secure it, and you won't have to worry about seeing that yellow and brown wire running right down that gap. Again, it's not the biggest deal in the world but it will make it look nice for you. Put tape around there just to hold it up into position. Now we can get this taillight put back in position. Now we can follow that same process to remove the passenger side taillight. To that mount our box, we're going to clean the backside of that off with some rubbing alcohol. And right up in that little open area there, there's a nice flat piece of metal. We're going to mount it right to that which we're also going to clean off. Replace that foam pad back there in the back. Tear the other side of it off and stick it right into position. Now for our ground wire, we just want to bring that up and attach it to a nice, sturdy piece of steel. You can see that's double there so that will be a great attachment point for us. We us a quarter inch bit drive or a socket and we'll start our hole. Once that's started on our ring terminal and we just want to secure that down so we can't wiggle that terminal. Now we'll start with the four pole wire which is the four color wire and our green wire and we're going to attach this right along the supports for the bumper here. The four pole, of course it needs to stop there right around where the hitch is. And the green wire, it's going to run all the way over to the passenger side. And once we get to the middle here, we'll just let our four pole hang. We'll finish that up in a minute and continue on with our green wire. And again, they provided one is it ties with the kits we could use them up to get a lot of good attachment points to keep everything where we want it. This button is going to pass right up through the same spot that we did on the other side and while we've got this right here, we can get our wire loom put in position. Now our excess green wire here, we can get this bundled and of course we will zip tie it off to keep it up and out of the way. And we can do the same thing up here with whatever four pole wire we don't think we're going to use. You want to have enough for your trailer but you don't necessarily need too much. Right around our hitch and I like to use the plug to go through the safety change connection to plug that into. Keep it up there without having to worry about it bouncing around or dragging down the highway behind us. Now we can get our 12 volt power wire ran right up towards the front of the vehicle here. Anywhere we can we want to anchor that wire out. As we do this we need to avoid any sharp metal objects, any really significant sources of heat, any pinch points. or anything else that might do any kind of damage to our wire. And zip tie it up at any connection point you can just to keep it up and out of the way and safe. And once we get to this point, I just need to tuck our wire right up into the engine compartment area there and then we will be able to find that from the top and hook it up to our battery. Now we can grab our wire, we're going to get that pulled right up here right by our power distribution center You just want to look back in there, confirm you don't have anything wrapped up around it, and then we can zip tie it off for an anchor point up higher. Now with this cover in the front in the back there are a couple little tabs. We can just pull out on those, you see them kind of right here. Pull out, that cover is going to slide off. We're going to use this wire where it connects in right here to make our connection. Bring that wire up. You want a little bit of extra. We're going to be able to snip that off and get it stripped back. We'll grab our butt connector, place that on, and secure it. Then we'll grab our fuse holder. We're going to cut that to get both ends of that stripped back. The longer side of that, this side, will connect to that butt connector and the shorter side it's going to get the provided ring terminal. Remove the nut off of that stud. Use holder pass there and we're just going to sit this right on top. For one of the last steps we'll slide in our fuse, cap that off, and then we'll tidy up our excess here. Now we just need to slide our cap back down on, get those little tabs to lock into position. Now to test out our installation we're going to use part number I26 here. It's just a simple plug in four pole tester. And as we go through the lights, we should see it correspond letting us know that everything's working properly. We will start by turning on our running lights, we'll do our left blinker, we'll do our right blinker, and also our brakes. Now with everything working correctly that's going to complete our installation of the Tekonsha T1 vehicle wiring harness with a four pole flat trailer connector. Part number is 118722 on our two 2016 Ford Transit T-350.

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118722

Average Customer Rating:  4.8 out of 5 stars   (32201 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. Powered ModuLite reduces strain on wiring system.

- 118722
2016 Ford Transit T350

As always quick and responsive order processing. Received my hitch and wiring harness in 4 days. Install of the hitch is simple, it took less than 10 minutes with the proper tools. (Impact is a must). Wiring harness connectors were a little off, easily corrected by shaving off the right side fin. If you want keep the wiring inside the van, remove the rear step trim and the driver side rear panel you can find power back there and save yourself running it all the way to the battery.

- 118722
2016 Ford Transit T350

I did the install today. The plugs were tight going into the factory plugs had to use a pair of pliers to get one to seat all the way. The wire running up to the front fell a little short. I had to pull it back re-route it in a less that ideal run, but it just made it. This is the first time I have ever had an issue with a product I have ordered from etrailer. I have ordered and installed several hitches, brake controllers, and truck accessories.

- 118722
Ford Transit Connect

Ordered what I hoped would be everything I needed to install hitch, trailer wiring, and trailer brake system for a ford transit. was surprised that it actually came with everything I needed! Being a mechanic I've installed lots of aftermarket things and had to piece them together. very good kit, great prices, and awesome instruction videos on youtube.

- 118722

Good product. If you've never installed one of these before, I recommend the tutorial video on YouTube. My wife and I followed the video step bey step, and got it all done in about 2.5 hours ( it was night time too, used flashlights a lot). I was waiting for Ford to get their manufacturer part back on to the market, but two+ months later I had to buy anrrrrrrrrrrrrrrrrrrrrrrrrrrr after market version. It is great, my only complaint was the high cost of shipping.

- 118722
2016 Ford Transit Connect

This is a great kit to set up the trailer wiring on the 2016 Ford Transit, it came with everything I needed to install the wiring plus some. The installation video was very helpful to watch before I started and made it easy work, it took me about an hour to do the complete install in my back yard.

- 118722
2016 Ford Transit T350

The instructions were simple and easy to follow. Easy installation. Hardest part were the tail lamp connectors, the kit connections seemed to be the wrong size and had to use a lot of force to get them together. That was the only concern I had, the rest was easy. Install time about an hour. Matching the Ford connections perfect would have given 5 stars, but this is really a 5 star product past that minor setback.

- 118722
2015 Ford Transit T350

The package had everything needed to make the installation. I followed the directions and it was pretty simple. The only issue I had was that the instructions said to connect the black power wire to the "red" wire on the module. Sorry, there is no red wire to connect to. I guess they may have more than one module which may have different color wires. I connected the black power wire to the "black" wire on the module. Very easy install. I ran some small plastic tubing under the van and slid the black wire into it as a sleeve for more protection. Thanks.

- 118722
Ford Transit Connect

Perfect fit on my Transit 350HD DRW Fish wire for rear bolts worked like a charm, have to admit I had my doubts when I 1st read the installation instructions. All in all a pleasure to deal with on the phone and will highly recommend etrailer to Friends

- 118722
Ford Transit Connect

Installed this on our Ford Transit about a year ago, no issues, fairly simple to install with the helpful videos. No complaints; works great.

- 118722
Ford Transit Connect

Very easy install with clear instructions, although the sockets were very tight I managed to successfully put the kit together. Id recommend this to other transit owners.

- 118722

This product was so easy to install. Everything needed for the installation was in the packet. The video was as helpful. It explained everything in detail how to install. Over all I would give this company 5 stars. thank you for your help.

- 118722
2015 Ford Transit T350

I just completed my installation of hitch and light controller. As always with etrailer it was very easy. the products are excellent quality and the instructions clear and easy to follow

- 118722
2018 Ford Transit Connect

For the 2018 transit 350 Hd extended you will need to add about 10 feet of wire for the 12 v supply.

- 118722
2016 Ford Transit T350

Great product, shipping was fantastic and quick, installation was a breeze! Thank you!!

- 118722

very easy to install and of great quali ty

- 118722
2015 Ford Transit T350

Very impressed with product works as it should. Highly recommend.

- 118258

Review from a similar T-One in Custom Fit Vehicle Wiring

Product quality very high, delivery very fast, shipping container (cardboard box) was not strong enough to support handling/shipment, box bottom was ruptured with hitch assembly hanging out, box should be supported stronger, no parts missing, hitch was scratched up somebut, nothing that a little black paint didn't fix. I installed the wiring harness connections and fuse box on the external side of the vehicle to eliminate having to take apart the internal sheet metal panels and providing easy access to the fuse in the event of fuse failure, this eliminates the necessity of interior Panel removal to change a fuse. Easy installation, product has great great design features ,great customer service with prompt delivery. Just ordered the bracket (#18140) to secure the 4 prong plug to the hitch neatly and secure to eliminate the loose plug. (not shown in photos (Bracket in transit),

Great, works like a charm.
Anthony J - 09/27/2020

- 118252

Review from a similar T-One in Custom Fit Vehicle Wiring

Just installed Draw Tight hitch, wire assembly along with the brackets for a nice look. Everything went smooth with installation and it has a nice clean look as the hitch is well hidden. This is going to work for our bike rack and the cargo carrier I am now going to by. Now I can also get a small utility trailer to pull and haul stuff. I strongly recommend etrailer for all your needs as they communicated with me the whole way through and readily replaced a lock unit that somehow came without the key. Customer service is top notch.

Absolutely Fine!
Scott N - 04/26/2020

- 118264

Review from a similar T-One in Custom Fit Vehicle Wiring

This is a perfectly tailored product for the do-it-yourselfer who with a little help adds a nice hitch to his vehicle. Getting an older vehicle's OEM installed weld nuts clean takes most of the time followed by installing the two washers and nuts in the fascia area. That part needs patience as the work area is limited. The Curt LED 4-Way Flat Connector (Vehicle End) Tester makes it very simple to verify the Tow Package - 4-Pole Flat Trailer Connector that is a snap to install to the vehicles pre-existing harness. One point to pay attention to in the instructional video is when pulling the square washer and bolt through the channel. They must slide in single file as shown. If you try to pull with the bolt through the washer it will get stuck and you will need to fish it out. So bottom line. Great product. Great support. Steve Stewart

Everything from the hitch to the wiring still works perfectly. Very pleased with the results
Stephen - 05/07/2020

- 118269

Review from a similar T-One in Custom Fit Vehicle Wiring

Plug & play for 2020 Kia Sorento. Dinged a star because the trailer connector does not fit the extra bracket well. It does not appear to have been designed for a bracket mount. I had to force fit and secure in place with a zip tie.

- 118248

Review from a similar T-One in Custom Fit Vehicle Wiring

Instructions provided with adapter are good. My 04 Highlander without tow package had the connector under rear, driver-side cargo tray. Lift the cargo floor, remove the tire-change-tool tray, remove the two plastic nuts on the bottom of the left-side tub, and lift it out. Also under that storage tub is an unused 6mm threaded hole in the body to be used for the ground. Put a fuse in the correct spot of engine compartment fuse block (mine was empty) and good to go. See underside of fuse block lid for tow adapter fuse placement.

Used 20 times this summer with no issues. I would buy again.
Michael A - 01/09/2021

- 118265

Review from a similar T-One in Custom Fit Vehicle Wiring

Needed a harness for my 2015 Honda Pilot LX and didn’t want to pay a king’s ransom for dealer parts and install. Ordered from etrailer and got a deal. Came with everything I needed and also had excellent, easy to understand instructions. Works perfectly.

This harness has worked like a charm. No problems at all.
Randy B - 06/01/2020

- 118266

Review from a similar T-One in Custom Fit Vehicle Wiring

This kit worked great. It took about an hour to install on my 2005 Xterra. The process was just like the video on etrailer.com. The only difference was that I mounted the bracket directly to my bumper instead of the hitch.

Working great. Im glad I purchased the 7-pin version for this car
Keith - 07/16/2020

- 118249

Review from a similar T-One in Custom Fit Vehicle Wiring

If it were not for the Great Hitch I bought from you that I installed at a DIY garage I would be Homeless during this PANDEMIC, your Hitch saved me from all kinds of problems Your Product is Great!

- 118252

Review from a similar T-One in Custom Fit Vehicle Wiring

FITS the new 2020 HIGHLANDER! There is a new connector with the 2020 Highlander redesign under the driver side rear bumper. This cable plugs directly into the Highlander connector. See photo. There is no need to route or run wires for the trailer wiring. You will also need a converter to provide the correct signals to this cable. I recommend using the Toyota Plug-n-play converter part number: PT725-48200. It’s around $60 online. Be aware it is installed behind a panel located next to the driver’s side second row seat. Toyota completely changed the vehicle wiring for the 2020 model year. I also recommend the CURT C99FR hitch. Fits perfectly, easy to install and hides behind the bumper.

Show More Reviews

Ask the Experts about this Tekonsha Custom Fit Vehicle Wiring

  • Trailer Wiring Recommendation for 2016 Ford Transit T350
    You would see a round connector near the bumper of your 2016 Ford Transit T350 that the part # C55774 would plug into if you had the factory wiring. Most likely you do not though and would need the trailer wiring harness part # 118722 which is a custom fit and would work well. I attached an install video for you to check out too.
    view full answer...
  • Parts Needed to Add Electric Trailer Brake Controller on a 2020 Ford Transit T350
    The parts you need kind of depends on what you already have for your 2020 Ford Transit T350, but I'll give you a list of all the parts you need either way. If you already have a trailer hitch and basic wiring like the T-One # 118643 (single rear wheel) or # 118722 (dual rear wheel) installed on your Transit then you need the Universal Wiring Kit # ETBC7 which plugs into your existing 4-Way and provides you with all of the connections and wiring for a brake controller. For a brake...
    view full answer...
  • Parts Needed to Install Brake Controller in 2017 Ford Transit T350
    Installing the Tekonsha Voyager Brake Controller # 39510 with Harness # 20127 on your 2017 Ford Transit T350 does in fact require a 4-way as well as the Universal Installation Kit for Trailer Brake Controller # ETBC7, and we do state in multiple areas that a 4-way is required, including the ETBC7 product page as well as fit guide pages and help articles which I have linked for you. The reason a 4-way is needed is because it gives you the basic lighting functions. The Upgraded Heavy Duty...
    view full answer...
    Image 1 for Image 2 for
  • 4-Way Trailer Wiring Harness that Fits 2019 Ford Transit 350 Dually Extended
    Since you have the dually extended version of the 2019 Ford Transit T350 the 4-way wiring kit you'd need is the # 118722. We had the chance to install this kit on a Transit like yours which I attached an install video link for on this page. The video shows a single rear wheel version but it fits the dually models too.
    view full answer...
  • Trailer Hitch Hardware and Wiring Harness for 2016 Ford Transit T350
    If you purchased the Curt Trailer Hitch Receiver # C13193 from us then all the necessary mounting hardware should have been included. Sometimes the hardware kit is well-hidden inside the hitch receiver so I recommend checking in there to make sure it's not there waiting for you. If you did purchase the hitch from us and the hardware is missing just let us know. Otherwise if you purchased the hitch somewhere else and simply didn't get the hardware as well this can be obtained with part...
    view full answer...

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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jameson C
Expert Research:
Jameson C
Employee Kathleen M
Video by:
Kathleen M
Employee Cole B
Installed by:
Cole B
Employee Randy B
Test Fit:
Randy B
Employee Chris R
Video Edited:
Chris R
Employee Sarah W
Updated by:
Sarah W
Employee Isabelle B
Updated by:
Isabelle B
Employee Alexander C
Written by:
Alexander C

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