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  1. Custom Fit Vehicle Wiring
  2. Tekonsha
  3. Custom Fit
  4. Trailer Hitch Wiring
  5. 4 Flat
  6. Powered Converter
T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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

Item # 118637
Our Price: $79.36
You Save: 27%
Custom Fit Vehicle Wiring

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118637 - 4 Flat Tekonsha Custom Fit Vehicle Wiring
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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. 1-800-940-8924 to order Tekonsha custom fit vehicle wiring part number 118637 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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Tekonsha Custom Fit Vehicle Wiring - 118637

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • Powered 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. 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 in trunk
    • Plug in T-connector
    • Run hot lead to car battery
  • Includes ModuLite to ensure that your vehicle's wiring matches that of your trailer
    • Powered module 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: 2.1 amps per circuit
    • Tail lights: 5.6 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 tail lights on both the driver's side and passenger's side. You will need to remove three screws on each side to access the harness. Once you've plugged in the T-connector, run the hot lead with the attached fuse holder to the car battery. Connect the fuse holder to the positive terminal on your battery and insert the provided fuse.

Once installation is complete, the 4-way 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. Because most trailers run on a two-wire system - wherein the brake and turn signals are carried on one wire - the separate brake and turn signals from your vehicle's three-wire system need to be combined so they are compatible with the wiring system of your trailer. This power module functions as a tail light converter to combine the brake and turn signal functions of your automobile so that they run on one wire to properly activate your trailer's tail lights. Note: This will not affect how the tail lights on your vehicle operate.

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.

118637 Tow Ready T-1 T-Connector - 4 Wire - Modu-Lite

Installation Details 118637 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 - 118637

Average Customer Rating:  4.7 out of 5 stars   (124 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.


Works Ok ... connectors hard to fish through narrow openings on my 2019 KIA Soul. However the trailer lights stay on with ignition off, lights off if the connector is left plugged in. Not a huge deal but unexpected.

2015 Kia Soul

Its been a year now and I love this hitch! I've towed a motorcycle trailer (with 850# bike) across the country, I've put an extra luggage rack on it and I've had absolutely NO problems with it!!


Good quality easy install great delive ry


This harness was not too bad to set up. Of course there are pains like running the wires under the carpet and through the firewall to get to the battery under the hood, but that is to be expected. The only issue I had was that after getting everything wired up, the trailer lights did not work; but that was due to a faulty junction box. I contacted etrailer about it, they sent me a new one, I sent the defective junction box back, and the new one worked just fine. Great customer service and a swift and easy resolution.

2015 Kia Soul

I can't really say how good this particular product is because my son's dog chewed up the wiring before I could install it. Everything else I've gotten from e-trailer has been good, however, so I'm assuming this was, too. I still want to set up my 2015 KIA Soul so it can pull my little fishing boat, so I'll probably get around to ordering a new harness soon. Fortunately, the dog did not chew up the drawbar.

Tom B.


Just fine. I bought a new wiring harness to replace the one the dog chewed up. Pretty easy to install, works well.

Kia Soul

The installation video and instructions are very well done. The trailer hitch and wiring harness was a easy installation and fit my KIA Soul the way should. The product was of high quality and I've had no problems since installation. So there's nothing else to say except "Thank You"

David J.


No problems .Good quality.

2016 Kia Soul

Installed the wiring harness and the hitch assembly for my 2016 KIA today. I am in my mid 70s and installed both by myself and without any problems. Your videos are very good and helpful. I must say that your products are the best after market modifications that I have ever installed. Good job etrailer.

George C.


Both the hitch and the wiring are still working fine.You are selling a good product. Thanks.


Installed easily fit perfectly.

2016 Kia Soul

The trailer wire harness was easy to install, fit right. The trailer hitch was easy to install, perfect fit. Great products, great price and instruction easy to fellow.

Anthony B.


It was easy to install, the lenght is great, fits good

2015 Kia Soul

Read the directions and watch the video and you should have the hitch on in no time. Looks great, doesn't stick out to far and still have a lot of ground clearance. The pictures of the Kia Soul are EXACTLY like my Soul. Note: If you start on the driver's side and finger tight it first, you don't need to remove the EVAP canister at all. Pop the two clips for the inner fender , tuck them out of your way on each side and the rear muffler hanger and it will take you less than 15 minutes....maybe 20 if you don't have a beer assistant. :)

Ken J.


Very good! I use it to tow a small trailer with a canoe and motor. then I also use it to carry my bikes. everything works great!

2014 Kia Soul

Have not installed the hitch as yet, but based on a similar prior purchase, do not anticipate any issues. The hitch quality is excellent, and although pricey, the wiring kit is custom fit.

Soul M.


So glad I got the hitch and the plugplay wiring assembly. Made it MUCH easier. The hitch fit perfectly and the wiring was a snap...except I think I mentioned that the leads on the harness going to the car could have been longer, had to splice extra wire in and mount to a different area. But, after many miles of towing, all seems well. Thanks for the follow-up!

2016 Kia Soul

This is my second trailer hitch and wiring assembly purchase from e-trailer and this experience equaled my first. The hitch matched perfectly to the factory mounting points and the instructions from e-trailer provided for a nearly effortless installation.
The wiring harness was a bit more difficult to install, however that was due to my minimal skills and the auto's design, not that of the harness itself. Again, the e-trailer documentation was a great assist in completing the job. The build quality of the hitch and harness were excellent and I would highly recommend e-trailer for your trailer towing accessory needs.

2019 Kia Soul

Thanks for the great customer service! I received my product very quickly, and in excellent condition. I have not installed it yet, but I have ordered and installed this unit before, so I don't expect any issues with it. Quick and easy installation, and a great video on your site to assist in installation. Looking forward to being able to haul all kinds of things with my trailer again!

Heidi B.


Still working after a year of hauling and moving stuff. I have had no issues with the wiring harness. The reason I purchased a second one was because my first car was totaled in Hurricane Michael and I had to get a new car, and forgot to remove the wiring harness before I turned it in!

2013 Kia Soul

I recently purchased the Curt Class I trailer hitch and I absolutely love it! It was easy to install exactly per the instructions. I had to jack up the rear of my 2013 Kia Soul, but that was so I had more room to work. I recommend jacking up the vehicle but please be safe and use jack stands, block the front tires and make sure the emergency brake is set. The wiring harness was a bit more of a challenge, but very much worth the effort. I found the only difficult part was routing the 12 volt power lead from the battery to the rear of the vehicle. If you are routing the wire along existing wiring, be prepared to pull trim parts off the interior and make a hole in the rubber grommet from the engine compartment to the interior. Overall great product and it fits existing tail light connectors exactly.


It was a shame that I had to reorder this part. When I put my year, make and model of car in and order a hitch one would think the wiring harness shown would be the correct one for my vehicle. The turn around time was really good though.

Etrailer Expert

Jenny N.


I will have our customer service team reach out to you.

2013 Kia Soul

Love the DrawTite hitch! Its exactly what I needed. I also bought a Curt hitch mount cargo carrier. It works great for extra cargo room or for things such as my fuel jugs for my lawn equipment and other things Id rather not put inside the car. I also bought the T connector for the trailer lights and it was fairly simple to install and there was no splicing into the vehicle wiring. Shipping was fast also!

2011 Kia Soul

I received my order within three days of placing it. I took everything to hitch installation shop and they charged me $125.00 to install hitch and wiring harness. Perfect fit, looks good (for a hitch) and harness worked well. Very pleased with the service and product from etrailer. They acknowledged my order by email and kept me apprised of status including letting me know when it was delivered. I had noticed that it was sitting by my gate until I received their email and checked. Very Pleased!


This is a good product, however the reason it got 4 stars is the difficulty with installation. The videos were great, but the ease with which the video installation went was not apparent on my vehicle. I had to rent a thread puller to get the final bolt to attach. It was a full day, kind of frustration job that ended at about 10 pm. Once installed, its worked like a champ, and the wiring harness I purchased needed no modifications. All around the product is as advertised, just be prepared for a bear of an installation.

2015 Kia Soul

I ordered this and received it quickly. I will be using it to pull my new Sylvan Sport Go Trailer full time. This is exactly what I needed and for a good price. My sister's fiance assembled the hitch and wiring on my 2015 Kia Soul in 2.5 hours. He utilized the videos on this site as well as another on Youtube and did it with little issue. If I need anything else I would definitely buy from this site again.


The wiring harnass was fine, but the E trailer video neglected to show all the steps. It was necessary to remove 3 screws on the tire "inner splash guard" in order to access the wiring harness in one phase of the installation. This step was not explained in the video. You just had to figure out what the installer did to get to the place where he was in the video. I also found it helpful to remove the tire when securing the "black box" to the bumper. Otherwise, there was very little room to work.

2016 Kia Soul

The video for installation on a 2013 Kia Soul made it look simple. Installation on a 2015 Kia Soul is significantly more difficult. The connectors do not just simply gravity feed to the bottom. It is a fight to get them through the openings. I read in the comments that the left side connector needs to feed over the top of the bumper mounting brackets. That seems to be nearly impossible without disassembling the entire bumper. The wiring is not long enough to go under the bumper brackets to reach the left side. Spending 16 more cents on increasing the length of wiring would have made this issue go away. Lastly, the video indicates you can install the battery wire along the left side of the shroud underneath. They forgot to mention the battle you are in for getting under that shroud. I did get the wiring installed and working, but this project should be done without children around because there is going to be a lot of swearing.

2014 Kia Soul

I couldn't be more happier with my purchase of a hitch and wiring harness from The hitch fit like a glove!!!! No standing around waiting for a shop to install and overcharge. I will be telling everyone I know to order from them. Fast shipping too!!!!!! Will be back if I ever need another hitch and harness for another vehicle. Great job Thank you, thank you, thank you


etrailer is great. I bought a wiring harness and when it started acting up, they were willing to send me a new one to try with the agreement that if it didn't fix the problem, I would pay for it. I couldn't be happier with etrailer.


One year later and the wiring harness is going strong, no issues at all.
I had a local shop do the install to replace one that [retailer] had put in, that original install lasted about 9 months before things started shorting out and causing major issues. So far so good with this one. etrailer was recommended by the garage that did the replacing and they know what they are doing with all my repairs.

2016 Subaru Forester

Ordered 2 hitches and wireing, one for 2016 Kia Soul and one for 2012 Subaru Forester, installed one on Soul and only problem was length but turned out long enough but you have to make sure to get it over top of bumper brackets and it will reach. Have yet to install on Forester.

Show More Reviews

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

  • What is the Preferred Way to Route Power Wire of a Powered Trailer Wiring Harness
    There are a few different ways to run the power wire of a powered trailer wiring harness like the part # 118637 that you referenced. Typically the easiest way is to run it out the floor of the vehicle through a grommet in the floor and then up to the battery using zip ties to secure the wire away from exhaust and moving parts. I attached a help article that details the different ways to run this wire for you to check out as well. I also attached an install video for this harness for you...
    view full answer...
  • Trailer Wiring Recommendation for a 2014 Kia Soul
    Yes, when people install light bars at the rear of their vehicle like what you often see below the tailgate of a truck it's trailer wiring that gets used to activate it. If you were talking about a lightbar like what you see on a police car, we don't have a solution for that... So for your 2014 Kia Soul you would want the # 118637 which I attached an install video for.
    view full answer...
  • Does Trailer Wiring for a 2014 Kia Soul Activate the Trailer's Brake Lights as Well
    Yes, the trailer wiring harness part # 118637 is designed to activate your trailer's brake lights when you activate the brake lights of your tow vehicle. This will plug in line with the taillight circuits of your vehicle to allow them to basically control the taillights of your trailer. Check out the install video I attached for this harness as well.
    view full answer...
  • Trailer Wiring Harness for a 2013 Kia Soul with Incandescent Tail Lights
    Tow Ready trailer wiring harness fits 2013 Kia Soul with or without LED tail lights. In our fit guide we have entries for both because there are other harnesses that fit one or the other but not both. But harness # 118637 does indeed fit both versions!
    view full answer...
  • Is Trailer Wiring for 2019 Kia Soul Compatible with LED Trailer Taillights
    Yes, the 4-way trailer wiring harness part # 118637 that you referenced which does fit your 2019 Kia Soul is perfectly compatible with LED trailer lights. It also fits versions of the 2019 Kia Soul that do and do not have LED taillights.
    view full answer...
  • Trailer Wiring Recommendation for 2014 Kia Soul Exclaim
    For your 2014 Kia Soul the correct trailer wiring kit you'd need is the part # 118637 which is a confirmed fit and will work well. I attached an install video for this kit on a similar 2014 Soul as yours for you to check out as well.
    view full answer...
  • 2012 Kia Soul Trailer Wiring Recommendation
    You'd have to look into a small trailer as your hitch won't have the capacity for a wheelchair and none of the carriers with ramps are made for your 1-1/4 inch hitch size. If you wanted to go that route we have trailer wiring part # 118637 which is a fit. I attached an install video for this for you to check out as well.
    view full answer...
  • Trailer Wiring Harness for 2014 Kia Soul w/ LED Taillights
    The Tow Ready # 118637 would be the correct taillight wiring harness for your wife's 2014 Kia Soul. If you click the provided link, you an see a video showing the # 118637 being installed on a 2014 Soul.
    view full answer...
  • Correct Trailer Wiring Harness for 2016 Kia Soul
    The Tow Ready # 118637 is the correct trailer wiring harness for all models of the 2016 Kia Soul. There are some vehicles that have various sub models, some of which will use LED lamps, some of which do not. Usually the taillight assemblies of the LED and Incandescent lamps will use different connectors, which is why we state With LED Lights and Without LED Lights. No worries, you have the correct wiring harness for your vehicle. You can view an install video by clicking the provided link.
    view full answer...
  • Recommended Trailer Hitch For 2016 Kia Soul EV Model
    I believe you are asking for a 1-1/4" hitch for the 2016 Kia Soul. I recommend Draw-Tite Sportframe Trailer Hitch Receiver - Custom Fit part # 24915 which is designed for all models of the Kia Soul even the EV model and has a 1-1/4" receiver. I have attached an installation video for your reference. This will give you a Class I 1-1/4" hitch on the back of the Kia Soul.
    view full answer...
  • Trailer Wiring Harness for a 2012 Kia Soul Luxury with LED Tail Lights
    I spoke with my contact at Tow Ready and for a 2012 Kia Soul with LED tail lights, you will need to use wiring harness # 118637. This harness will need to be hardwired into the vehicle using the included circuit tester to find the appropriate wires on the vehicle to tap into. It also requires a direct connection to the vehicle battery to power the trailer lights. I have included a link to the installation instructions for you to view.
    view full answer...
  • Recommended Trailer Hitch and Wiring for a 2015 Kia Soul
    The trailer hitch receiver that I recommend for your 2015 Kia Soul is the Draw-Tite Sportframe Trailer Hitch Receiver # 24915. This is a Class I, 1-1/4 inch hitch receiver that is compatible with all Kia Soul models with the exception of the EV model. For a wiring kit I recommend the Tekonsha T-One # 118637 which will draw power from the battery so that if the lighting on your hitch mounted accessory starts to have issues it will not feed back into the wiring on your Kia Soul (please...
    view full answer...
  • Availability of Trailer Wiring Harness for 2012 Kia Soul w/ LED Taillights
    We do indeed have a trailer taillight wiring harness that's compatible with a 2012 Kia Soul with the LED taillights. You'd want to use part # 118637. The wiring harness would plug inline with the factory wiring connection at the taillight assemblies, and one wire would need to be ran to the positive battery terminal. The # 118431 wiring harness you mentioned is only a fit for Soul models without the LED taillights. I'll link you to some FAQ articles that you might find helpful.
    view full answer...
  • Trailer Wiring Recommendation for a 2012 Kia Soul
    For trailer wiring on your 2012 Kia Soul you would want the Tow Ready Harness part # 118637 which is a confirmed fit. Price is at the product link below. I also attached an install video for you to check out as well.
    view full answer...
  • Troubleshooting Tekonsha T-One Harness Causing Tail Light on 2015 Kia Soul to Go Out
    The Tekonsha T-One Vehicle Wiring Harness # 118431 that you mentioned is only a confirmed fit for the 2015 Kia Soul if it does not feature LED tail lights. I first just recommend making sure you don't have LED lights on your Soul which may cause issues like what you're describing with this particular harness plugged in. If you do have the LEDs then the correct trailer harness is actually the Tekonsha # 118637. If you don't have LED lights I recommend making sure the T-connectors are fully...
    view full answer...
  • Troubleshooting Taillight Converter Thats Been Replaced Twice on 2018 Kia Soul
    The main reason why folks go through multiple trailer taillight wiring harnesses/converter modules is a short in the trailer wiring. I know, it's a new trailer but all it takes is one nick in the wire insulation when they were pulling the trailer wiring through the trailer frame and you'll continue blowing out converters until the end of time until you locate and repair the short. Since you're not getting any output on the taillight circuit, that's probably where the trouble lies. I'd...
    view full answer...
  • Choosing the Correct Class I Ball Mount to Pull a Small Boat Trailer with a 2014 Kia Soul
    To choose the correct ball mount you will want to make sure that you do check the weight capacity of it, but it is also equally important to make sure that you know what kind of Rise or Drop you need or if it is even needed at all. Keep in mind that you will need to check your owner's manual for any special instructions about towing. In an online manual it states not to use your 2014 Kia Soul for towing so if you do so you will be operating outside of the parameters of the manufacturer. What...
    view full answer...
  • How to Install Tekonsha 118637 Trailer Wiring Harness on 2014 Kia Soul
    The Tekonsha # 118637 trailer wiring harness is a confimed fit for your 2014 Kia Soul. I've linked you to both the installation instructions as well as to a video showing the harness being installed on a 2014 Soul like yours.
    view full answer...
  • Installation Instructions for the Tow Ready Wiring Harness for 2012 Kia Soul
    We haven't had the chance to make an install video for the # 118637 yet, but I did attach a couple sets of installation instructions for this harness and a similar one made by Curt (part # C56222), for you to check out.
    view full answer...
  • Parts Needed to Tow Smaller Trailer with 2016 Kia Soul
    We do have all of the components you'd need to tow a small trailer with your 2016 Kia Soul. For a hitch you'd need to start with the part # 24915 which is a confirmed fit, for a ball mount part # 3593, 2 inch ball # 19258, and finally trailer wiring part # 118637. This hitch would have no problem with a small trailer and small ATV, but you really need to check your Soul's owners manual to determine what the manufacturer recommends as a towing capacity.
    view full answer...
  • Trailer Hitch Recommendation for 2011 Kia Soul
    To transport a mobility scooter with your 2011 Kia Soul you'll have to use a small trailer as there aren't any cargo carrier setups that are going to be strong enough for the weight of the scooter on your Soul. You'll need a hitch like the Draw Tite part # 24839 which is a confirmed fit and trailer wiring like part # 118637. For a ball mount you'd want the part # 3593 which then for a hitch ball you'd want the part # 19256 for a 1-7/8 inch ball.
    view full answer...
  • EcoHitch for a 2019 Kia Soul EV Model
    The EcoHitch Hidden Trailer Hitch Receiver - Custom Fit - 2" item # 306-X7326 is confirmed to fit all models of the 2019 Kia Soul including the EV model. I have attached an installation video. According to EcoHitch's website there are no differences in installation with the different trim package. If you are looking for a wiring harness you will want the Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector item # 118637.
    view full answer...
  • Troubleshooting Trailer Wiring on a 2013 Kia Soul that Lights Up Trailer Lights All the Time
    It sounds like there was a short on your trailer that developed over the winter and when you connected your Kia Soul to it the short took out the converter box of the # 118637. If you want you can test to verify this, but I am very confident the box has shorted out and needs to be replaced. What you will want to do is test the wires going into the box of the converter box for voltage with a circuit tester like the # PTW2993 to see if there is voltage going into the box when the taillight...
    view full answer...
  • Trailer Hitch and Wiring Recommendation for 2016 Kia Soul
    Both the Curt and Draw Tite hitches for your 2016 Kia Soul are great options. I would go with the Draw Tite # 24915 instead though as it has the best price. I attached a link to an install video for you to check out as well. For trailer wiring you then would want the part # 118637 which I attached an install video for as well. For a ball mount you would need the part # 3593 and then for hitch balls part # 19258 for a 2 inch ball or part # 19256 for a 1-7/8 inch ball.
    view full answer...

Do you have a question about this Custom Fit Vehicle Wiring?

Info for this part was:

Employee Mike L
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Employee Cole B
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