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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 # 118731
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Custom Fit Vehicle Wiring

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118731 - 4 Flat Tekonsha Trailer Hitch 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. 1-636-306-4830 to order Tekonsha custom fit vehicle wiring part number 118731 or order online at 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 (20)
  • Q & A (0)
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  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118731

  • 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 rear cargo area
    • 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: 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 inside your rear cargo area, on both the driver's side and passenger's side. You will have to remove the rear threshold to access this harness. 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 connector will be stowed in your rear cargo area.

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. 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.

118731 Tekonsha T-1 T-Connector - 4 Wire - Modu-Lite Converter Included

Installation Details 118731 Installation instructions

This Product Fits The Following Vehicles

California residents: click here

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118731

Average Customer Rating:  4.8 out of 5 stars   (20 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.


Etrailer has always been great to do business with. Their website is very easy to navigate and you quickly receive the products in a timely manner.


Works as it should.


A very easy order process, quick delivery and I got a local mechanic to install the trailer hitch at a reasonable price. The tragedy is 3 months after I got the trailer hitch on my 2018 Nissan Altima SV I got rear-ended and the car was totaled. I couldn't get the trailer hitch off of it due to the damage.

2015 Jeep Wrangler

Wiring looks good out of package, what you would expect. Installed on a 2015 Jeep Wrangler, added LED brake light strip.

All connections worked except Brake light wire. Checked to verify connections were good. Source plug checked positive on all 4 connections, new wiring harness did not.

Removed and hardwired light direct.

Looked good but not worth time to find break in wire.

2017 Nissan Altima

T-one Wiring Harness With 4-pole Flat Trailer Connector
Wiring to the tail lights was easy. The hard part was finding a way to run the power wire from trunk to battery (Nissan 2017 Altima). It took me several hours to figure it all out. I ran wire in trunk to rear seat compartment, then down the drivers side below the door thresholds to front. Where possible I tried to follow other wiring along the inside of the car. Then when I wondered if I was going to be able to get to engine compartment, I found a little grommet going from near where the cable goes to the door. I was able to punch a hole in the little (about 1/2" diameter) rubber grommet and push my power wire through it to get outside. From there I was able to run the wire up behind the rubber seal going to the drivers side fender. Coming out the top I was able to exit at a covered run from there to near the battery. The time spent finding a way to run the power wire probably took over 6 hours. The car sits too low to the ground for me to run it below the car and the underside is all enclosed with plastic shields, so that was not a viable option. After getting it all connected, it did not work. The following morning I started trouble shooting at the battery and the wired were not secure in the yellow connectors even though I had squeezed them as tight as I could. One came out while I was unwrapping the electrical tape I had wrapped over them. I just decided to not use the supplied yellow connectors and solder the connections, covering them with shrink wrap tubing to prevent shorts. Finished, and everything worked perfectly. The problems I had were not with the wiring, but in the installation as described. Instructions were good.
I can not include photos as everything is all covered over in the car. All you can see now is the wire coming out by the trunk latch to connect to the trailer, and the wire coming out less than 12" from the battery. A very neat installation.

2016 Nissan Altima

The wiring harness was a perfect fit and installed quite easily. A bit of labor needed, but the time was well worth it to have a very clean installation. I am completely happy with it.


The trailer lighting adapter kit arrived safely in my mailbox and the transaction was just what I expected! Good detailes web description, then prompt delivery of a product that was what I needed. What else could be expected?


Great product, excellent quality, easy to install. On line video had great step by step installations instructions which made the install quick and easy. Product has worked perfectly. Better product than [trailer rental company], half the money and far superior product.


Easiest install of lighting in years. Everything fit exactly and instructions 99% clear.

2020 Nissan Altima

I ordered 2 complete hitch assembly kits. They fit perfect and look fantastic. You can hardly notice them under the cars.


Easiest set up ever. Hardest part running the power cable from the battery to the trunk. Everything else was simple.


Excellent advice during my phonecall...order received very quickly....price was great! Recommend everyone visit "etrailer"


I received it very timely and have it in place. It is working very well and I am completely satisfied with the way it is built. Thank you for sending it out right away.

Joe Peek


expensive, but easy to install. The hardest was installing the "hot" wire.


Excellent! Arrived on time and works fantastic with my vehicle

2017 Nissan Altima

I have a 2017 Nissan Altima. The towing capacity for the car is low. I plan to tow a dirt bike on a very light trailer to end up just over half of my towing capacity. During my research I found the website became my greatest resource for information and ideas. I ended up purchasing 4 items including a hitch assembly, draw bar, ball and wiring harness. I paid extra for expeditated shipping. I received a shipping confirmation from George very soon after my order. Delivery was early and complete. Everything is of the highest quality, I am impressed. Packaging was good and my order was protected. I am very happy, thank you !

2016 Nissan Altima

Good fit.





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

  • 2017 Nissan Altima Trailer Wiring Recommendation
    Some vehicles are more set up from the factory for towing like your Equinox, whereas for your 2017 Nissan Altima there is an easy way to install trailer wiring, but Nissan didn't specifically design your vehicle with towing in mind so they didn't give it a port for trailer wiring like the Equinox. So you'd want the Tekonsha kit part # 118731 which is a confirmed fit for your vehicle. You do have to run a wire up the battery so that your vehicle taillight circuits are protected though.
    view full answer...
  • What are the Towing Capabilities of a 2016 Nissan Altima SR
    From my research on your 2016 Nissan Altima, it is not recommended to tow a trailer or vehicle dolly. The trailer hitch receivers made for your vehicle like the Draw-Tite Sportframe Trailer Hitch Receiver # 24796 you referenced are light duty Class I trailer hitch receivers designed for carrying accessories such as a cargo carrier or bike rack. If you do decide to tow with your vehicle you will need a custom vehicle wiring harness like the Tekonsha T-One Vehicle Wiring Harness with 4-Pole...
    view full answer...
  • Trailer Hitch for a 2017 Nissan Altima Sedan
    For your 2017 Nissan Altima sedan you can use Draw-Tite trailer hitch # 24796. This is a Class I trailer hitch with a 1-1/4 inch receiver. If you want to use the hitch for an accessory such as a bike rack or cargo carrier then you have to make sure the accessory is rated for use with a Class I trailer hitch. Also, with a bike rack, you are limited to 2 bikes maximum on a Class I hitch. I have linked the Class I compatible 2-bike racks and cargo carriers for you. If you want to tow then...
    view full answer...
  • Bike Rack For Carrying a 48LB Specialized como 4.0 E-Bike With a 2021 Nissan Altima
    Due to the weight of your 2021 Specialized como 4.0 step over E-BIke of 48lbs you will need to use a platform style rack like the Thule EasyFold XT Bike Rack # TH903202. The Yakima FullBack 2 Bike Rack # Y02634 only allows for two bikes that weighs 35lbs each. Even by only carrying one bike you would still exceed the single bike weight rating for the rack and its components that hold each bike in place. It also looks like the battery only weighs about 8lbs so that would still not decrease...
    view full answer...
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  • Hitch and Other Equipment Needed to Tow Rental Trailer With 2020 Nissan Altima
    In order to tow your rental trailer, you'll need to install a trailer hitch like the Curt # C11352 and a trailer wiring harness such as part # 118731. You'll also need a ball mount like # C45521 and a trailer ball like # A-80 for a 1-7/8 or # A-82 for a 2 inch diameter ball. You'll also need a # PC2 hitch pin. If you click the provided link, you can see a video showing the hitch being installed.
    view full answer...
  • How to Carry Mobility Scooter with 2017 Nissan Altima
    You seem to already have an inkling of what you're going to run into. Because of the limited tongue weight capacity of a Class I hitch such as the Curt # C11352, the carrier used plus the scooter itself could not weigh more than 200 lbs. We don't offer any scooter carriers compatible with a Class I hitch, but there might be some out there. There are adapters that allow use of a 2 inch accessory in a class I hitch, but using those adapters lowers the hitch capacity by half to 100 lbs. What...
    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 Dustin K
Video Edited:
Dustin K
Employee Cole B
Installed by:
Cole B
Employee Wilson B
Updated by:
Wilson B
Employee Isabelle B
Updated by:
Isabelle B
Employee Alexander C
Written by:
Alexander C

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