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  1. Custom Fit Vehicle Wiring
  2. Jeep
  3. 2020
  4. Tekonsha
T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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

Our Price: $82.32
Custom Fit Vehicle Wiring

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Tekonsha Custom Fit Vehicle Wiring - 118786
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Call at 1-800-940-8924 for expert service. We are your Jeep custom fit vehicle wiring experts, and offer a great price. carries a complete line of Tekonsha products for your Jeep 2020. T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part 118786 from Tekonsha can be ordered online at Complete custom fit vehicle wiring installation instructions and technical support.
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  • Reviews (202)
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  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring

  • 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 behind tail lights
    • Plug in T-connector
    • Run hot lead to car 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 access cover and 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. 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 Power Module

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.

118786 Tow Ready T-1 T-Connector - 4 Wire - Modu-Lite

Replaces Tekonsha 118782

Item # 118786

Installation Details 118786 Installation instructions

Customer Satisfaction Score:

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118786

Average Customer Rating:  4.9 out of 5 stars   (202 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.

2018 Jeep JL Wrangler Unlimited

The quality of the parts is very high. The shipping was fast. I have not installed the harness yet but expect it will not be a problem as a video is available.


Easy to follow instructions and hitch is as described. I’ve had it on my Jeep a year with no problems. Installed myself in about 2 hours. If that seems like a long time, I’m 120lb chick working on gravel by myself.


The first hitch they sent had one nut welded on crooked so I was unable to thread the bolt in, I called them and they had another hitch to me in just a few days now that's service. I installed that with no problem and it has been working great.


I contacted etrailer in advance of buying the items needed to add a trailer hitch to my 2021 Wrangler unlimited Sahara. I was assured everything would bolt right up and the wiring kit was made specifically for my new jeep. When I received my wiring kit, it was for a jeep with the battery on the opposite side of the vehicle. So the instructions were different and it was more of a chore routing the wires from the battery to the tail lights. Just barely had enough wire to reach the other side of the vehicle. I ended up having to hire a shop to facilitate the install and spent over $200 for the install due to the difference between the items, instructions, and my Jeep. I wouldn’t be so frustrated except I took the time to reach out to etrailer staff and I was assured there would no problems.

When it comes to routing the power wire to the battery you can route the wire over to the passenger side at the rear of the front, it does not matter and it will not have any affect on the install or the system. You will just want avoid places where the wire would be pinched or exposed to heat along the frame rail. We do have a FAQ that is helpful.
-- Etrailer Expert Jenny N - 03/21/2022

2018 Jeep JL Wrangler Unlimited

I prefer to use this Tekonsha module for the vehicle that don`t have the factory tow harness. The module was tucked away in the body cavity behind the drivers side tail lamp assy. All wiring was covered in HD split loom. All wiring was concealed as much as possible by running them through the cross rail and frame rail up to the battery positive terminal. I did lengthen the green wire on the passenger side to accomplish this. All connections were done with heat shrink connectors. Installation did take longer than usual based on the wire routing I chose. Overall I am totally satisfied with this product.


Have not yet installed…….. however, having the video posted to compare the two items, then to receive regular communications and extremely quickly shipping, provided an extremely rewarding experience. I have full faith and confidence in me etrailer after this, my first experience being as good as it was.


The actual harness was excellent. It had all the required materials. The only thing I had to purchase was some plastic convoluted tubing. The written instructions were useless. This video was very helpful

2019 Jeep Wrangler

Very satisfied with the etrailer wiring harness for my 2019 Jeep Wrangler JLU. Installation instructions were good. Components and wiring are of good quality and sufficient length. Would buy again!


Easy fit and straight forward if you have some knowledge of how to put things together.


This wiring kit was just what I needed to get trailer light connection on my 2021 Jeep. I have been very satisfied with all of my purchases from etrailer!


Hitch is well built. Wiring harness worked well.

2018 Jeep Wrangler

I installed this on my 2018 Wrangler and it was perfect. Very simple install. Videos were very helpful. Took about 3 hours by myself. It may have taken a little longer because I ran the battery wire inside the frame for protection. Seems to be very good quality and I would recommend this harness to anyone needing to add a trailer light plug to their vehicle. Thanks etrailer.

Jeep Wrangler

Installed on 2021 Jeep Wrangler Unlimited with Curt Trailer Hitch Receiver - Custom Fit - Class III - 2" Item #C13392. It's been a year since I installed it, but I believe it did not require a dedicated power line, which makes the install easier.


Quality product.
Followed the provided
video and aside from routing the power wire through the frame being a bit fiddly, the install was a snap.
If you have a few common tools and a little mechanical ability, install is a breeze.

No complaints. Item is worth every penny. Install video was exc.
Tim - 05/04/2022


Good heavy duty product

2018 Jeep Wrangler

I've purchased a handful of trailer hitches/wiring harnesses over the past 10 years and they have always been awesome!! Quality products and fast shipping every time!! Just recieved a new class 111 hitch & wiring harness for my 2018 Wrangler JL and installed the hitch in less then 10 minutes and the wiring was approximately an hour after watching the video provided on their website. Never been disappointed!!


Great doing business with you very easy and always someone to TALK to

Jeep Wrangler

Nice straight-forward installation videos helped to be sure I was getting everything right. Quality product that has worked great for over a year and counting. 2021 Jeep Wrangler Unlimited.


Easy to match the hitch I needed with my vehicle using the website. I was also able to pick out the wiring harness I needed as well. After being ordered it was shipped quickly with an email providing shipping and tracking information. Perfect fit to my vehicle. Very pleased with my purchase.


Had exactly what I needed to wire my Jeep up for trailer lights. Very quality wiring harness and easy to follow instructions. They ship very fast and keep you updated on where your package is. Highly recommend etrailer!!!


Everything was as advertised, instructions were clear and the price was pretty good.

2020 Jeep Wrangler

Kit worked great, had some trouble getting passenger side wiring pulled up in taillight housing due to small opening to access. I had to remove a lower splash guard panel in wheel well to get better access. I pulled power wire to battery thru passenger side frame, worked out great with electrical snake.


Easy to install, great product. ETrailer never fails me.

Very easy to install. No issues to date. Very happy with product.
Michael - 03/29/2022


Nice easy install. Wish it had heat shrink for the connectors, or heat shrink connectors.

Still Working great!
Kynndarrn - 04/29/2022


Top quality products at reasonable pricing along with fast shipping

Show More Reviews

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

  • Estimated Installation Time for Tekonsha 118786 Trailer Wiring Harness on 2019 Jeep Wrangler
    Tekonsha doesn't list an estimated installation time for their trailer wiring harnesses like they do with their trailer hitches, but after looking through the install instructions and viewing the linked installation video, I'd estimate that the install should take a professional about an hour, and a fairly capable do-it-yourselfer about an hour and a half. I'll also link to a help article that addresses how to run the wire from the rear of the vehicle up to the battery.
    view full answer...
  • Custom Fit Trailer Wiring Harness Recommendation for 2018 Jeep JL Wrangler
    For the 2018 Jeep Wrangler JL that you have we have the Tekonsha 4-way kit part # 118786 which is a confirmed custom fit and would work well. This installs by plugging inline with the tailight harnesses of your Jeep as you can see in the install instructions I attached below.
    view full answer...
  • Trailer Wiring Harness Recommendation for 2018 Jeep Wrangler JL
    For your 2018 Jeep Wrangler Unlimited Sport with LED taillights the Tekonsha kit part # 118786 that you referenced is a confirmed fit and will work great. This kit has the highest amperage rating which means it will be the most resilient to wiring shorts and overdraws, and installs very easily so it's overall the best choice. I attached an install video for this on a similar 2018 Jeep Wrangler JL as yours for you to check out as well.
    view full answer...
  • Trailer Wiring For 2018 Jeep JL Wrangler
    The Roadmaster Universal HyPower diode wiring kit part # RM-154 is different wiring than what you need for towing a trailer with the 2018 Jeep Wrangler JL. You will need a 4-pole flat wiring harness part # 118786 which will plug in behind the Jeep's tail lights. You will plug the trailer connector on the trailer into the 4-pole to power the lights. I have attached an installation video for your reference.
    view full answer...
  • Is Splicing Required to Install Trailer Wiring Harness 118786 on 2018 Jeep JL Wrangler Unlimited
    No, installation of trailer wiring harness # 118786 does not require splicing into the vehicle tail light wiring. It has connectors that plug in line with the tail light connectors on the 2018 Jeep Wrangler Unlimited JL models. A connection to the battery is required and will be what powers the trailer lights as well as part of what helps protect the Jeep's electrical system.
    view full answer...
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  • Will Trailer Wiring Harness 118786 Work on a 2018 Jeep JL Wrangler Unlimited with LED Tail Lights
    I checked with Tekonsha, the manufacturer of wiring harness # 118786, and there are no known issues with this wiring harness and LED lights on the new 2018 Jeep JL Wrangler Unlimited.
    view full answer...
  • Trailer Wiring Recommendation for 2019 Jeep Wrangler JL
    We have a confirmed fit for custom trailer wiring for your 2019 Jeep Wrangler JL as part # 118786 that we know will fit and work well. We can't really tell you if our competitors are up on the most current fit info though.
    view full answer...
  • Troubleshooting No Running Lights After Installing Tekonsha Harness on 2018 Jeep JL Wrangler
    There are a couple possible reasons as to why the running lights are not working after installing the Tekonsha T-One Vehicle Wiring Harness # 118786 on your 2018 Jeep Wrangler JL Unlimited. First, since this harness does require that a hot lead be run up to the vehicle's battery, I recommend making sure all the connections under the hood are secure. Since the Jeep's battery is what will actually be powering the harness, you will want to ensure that the black power wire from the T-Connector...
    view full answer...
  • Trailer Wiring Harness for a 2018 Jeep JL Wrangler Unlimited Sahara
    Apparently the 2018 Jeep JL Wrangler Unlimited Sahara and Rubicon models have a different type of tail light and the connectors on old wiring harness 118782 do not match up. In order to add a trailer connector on those models or other JL models you will need to use # 118786.
    view full answer...
  • 2018 Jeep Wrangler JL Unlimited 4-Way Trailer Wiring Harness
    For your 2018 Jeep JL Wrangler Unlimited the correct trailer wiring harness is the Tekonsha part # 118786 which is a confirmed fit. This installs by plugging inline with the taillight wiring of your Jeep to operate the trailer wiring. Of the trailer wiring brands on the market the Tekonsha brand is the most reliable.
    view full answer...
  • Does Trailer Wiring for 2018 Jeep Wrangler JL Unlimited Have to Run to Battery Post
    Not all vehicles can handle the additional amperage draw of the trailer taillights on the vehicle taillight circuits. Those vehicles need setup that draws power from the battery. Some vehicles have higher rated circuits that can handle this, and others need to have the power drawn straight from the battery to protect the taillight circuits. For your 2018 Jeep Wrangler Unlimited JL you need to install a harness that draws power from the battery to protect the taillight circuits. For that...
    view full answer...
  • Best Trailer Wiring Harness for a 2018 Jeep JL Wrangler Rubicon
    Yes, the T-One Vehicle Wiring Harness part # 118786 will work on all 2018 Jeep JL Wranglers with factory LED and incandescent lights. This is actually an updated harness that was made to replace the T-One Vehicle Wiring Harness part 118782 that had issues with certain packages. There will be no issues whatsoever using the T-One Vehicle Wiring Harness part # 118786 on your 2018 Jeep JL Wrangler Rubicon.
    view full answer...
  • Can Trailer Wiring be Run Under 2018 Jeep Wrangler JL
    You can absolutely run the 12 volt hot lead of the T-One Wiring Harness # 118786 under your 2018 Jeep Wrangler so long as you can find a way to route it to your battery. In fact, the linked directions state this as an option, which you can see by the accompanying cut out.
    view full answer...
    Image 1 for
  • No Power to 7-Way on a 2018 Jeep Wrangler JL
    Which pin are you testing on your 2018 Jeep Wrangler JL's 7-way? If it is the 12 volt power feed then you will need to check for a blown fuse. In the power distribution center (PDC) on your Jeep there will be a pink 30 amp fuse in the F37 slot that controls 12 volt power to the 7-way. If you are referring to the brake, stop/turn, or tail light pins then these will only show power while the circuit is active.
    view full answer...
  • How to Install a Trailer Wiring Harness on a 2019 Jeep Wrangler
    Yes, the installation of a trailer wiring harness will be different for a 2019 Jeep Wrangler MOAB when compared to a 2013 Jeep Wrangler MOAB but not by much. Instead of just plugging in one connector behind the driver side tail light you will need to plug in a connector behind the passenger side tail light as well, run a power wire to the Jeep's battery, and ground the harness to a bare metal surface. For the above, I recommend using the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer...
    view full answer...
  • Trailer Wiring Harness Recommendation for 2018 Jeep Wrangler JL
    The trailer wiring harness I recommend for your 2018 Jeep JL Wrangler 4-cylinder is the Tekonsha kit part # 118786 that you referenced. This is a custom fit harness which means it will install easily and it comes with a very reliable converter box so it will last a long time too. I attached an install video for this kit on a 2018 JL just like yours for you to check out as well.
    view full answer...
  • 2018 Jeep Wrangler Unlimited Rubicon Trailer Wiring Harness Recommendation
    For your 2018 Jeep Wrangler Unlimited JL Rubicon the T-One 4-way harness part # 118786 is a confirmed fit that will not cause any dash lights to come on. This would be a great solution. This is our most reliable trailer wiring brand so we recommend it the highest. It installs by plugging inline with your taillight assemblies which allows it to function without the vehicle wiring even knowing it's there.
    view full answer...
  • Does Trailer Wiring Harness have to Connect to Battery on a 2018 Jeep JL Wrangler
    There are several reasons why the power wire has to connect directly to the vehicle battery when installing trailer wiring harness # 118786 on your 2018 Jeep JL Wrangler. First, the 12 volt accessory circuit was not designed to support the additional power draw of the trailer wiring harness. A wiring harness must have its own dedicated fused connection to the battery. Second, attaching the power wire to the battery maintains the level of separation between the vehicle wiring and the...
    view full answer...
  • Best Trailer Wiring Harness for a 2018 Jeep JL Wrangler Sahara
    Yes, the T-One Vehicle Wiring Harness part # 118786 which replaced the T-One Vehicle Wiring Harness part 118782 is now compatible with Sahara and Rubicon editions of the 2018 Jeep JL Wrangler.
    view full answer...
  • 4-Way Trailer Wiring Harness Recommendation for 2018 Jeep Wrangler Unlimited
    For trailer wiring the most reliable brand we offer is the Tekonsha brand by far so it's the brand I recommend the highest. So for that you'd want the # 118786 which is a confirmed fit for your 2018 Jeep JL Wrangler Unlimited and is compatible with the taillight style you have.
    view full answer...
  • No Power to 7-Way On A 2018 Jeep Wrangler
    Then it is possible that your 2018 Jeep Wrangler is not equipped with a trailer tow package. I did take a look at the owner's manual for the Jeep and F37 is the correct fuse placement if the Jeep is equipped according to the manual. Did you just install the 7-Way plug? If so, you may need to have the towing functions activated at the dealership. This is a fairly common issue.
    view full answer...
  • Wiring Harness for a 2022 Jeep Wrangler
    Yes, there is a wiring harness that does not require cutting or splicing wires available for your 2022 Jeep Wrangler. It is the Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector item # 118786. This custom-fit T-One connector plugs into your Jeep's wiring harness behind your rear tail lights. It plugs in-line without having to cut into the harness.
    view full answer...
  • Troubleshooting Trailer Wiring of Jeep Where Only 12 Volt Accessory Circuit Works
    Typically this problem is caused by corrosion or dirt on the trailer wiring pins. I'd first try cleaning all of the pins of the 7-way with sandpaper and make sure none of them are bent or damaged. Other place to check is fuses under the hood of the vehicle if the wiring is OEM. You can also check to make sure the wiring behind the connector isn't damaged. I attached a link to a page that covers trailer wiring troubleshooting for you to check out as well.
    view full answer...
  • Does Tekonsha Trailer Wiring that Fits 2020 Jeep Wrangler Allow Signals to Pass Through
    The connectors of the Tekonsha kit part # 118786 that fits your 2020 Jeep Wrangler Unlimited are pass through. If they were not the vehicle taillights would not function after the install. What this kit is designed to do is detect the signals that are passing through to the vehicle taillights and then send that info to the converter box which then draws power from the vehicle battery to power the trailer taillights.
    view full answer...

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Info for this part was:

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