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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 # 118729
Our Price: $68.94
You Save: 31%
Custom Fit Vehicle Wiring

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Custom Fit Vehicle Wiring 118729 - 4 Flat - Tekonsha
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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 118729 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.
  • All Info
  • Reviews (12)
  • Q & A (0)
  • Photos
  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118729

  • 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 power converter to ensure that your vehicle's wiring matches that of your trailer
    • Powered module connects 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 need to remove the rear threshold, cargo trays, and some interior paneling 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 flat 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. 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.

118729 Tekonsha T-1 T-Connector - 4 Wire - Modu-Lite Converter Included

Installation Details 118729 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 - 118729

Average Customer Rating:  5.0 out of 5 stars   (12 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.


The comprehensive video instructions are very easy to follow and is what sets etrailer apart from the competition. The kit works great and gives you all the parts and support you need for a professional installation.


It’s a good products


It works, what can I say... enough cable length, clear instructions. Where i spent my time was on routing the cables in such a way that it was away from the road, away from moving suspension parts, and away from the heat of the engine.


Have not opened the box yet but seems like I received what I ordered and quickly.
I like the instructional wiring video.
Easy to use web site


2019 Toyota Corolla Hatchback

Emailed me as soon as it shipped and it got here in 2 days!!! Extremely happy with the service and ready to install it on the car..



2019 Toyota Corolla Hatchback


Friendly, helpful fast!!!!!!!

2017 Toyota Corolla iM



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

  • Can Curt Trailer Hitch C11567 Be Used To Tow 589lb Trailer W/ 2020 Toyota Corolla Hatchback SE?
    The Curt Trailer Hitch Receiver - Custom Fit - Class I - 1-1/4" # C11567 you were looking at for your 2020 Toyota Corolla Hatchback SE has a 200lb tongue weight rating and a 2000lb trailer weight rating so in that regards the hitch will not have any problems with your 589lb trailer. Since Toyota and the trailer manufacturer told you there would be no issue, and the hitch has the correct ratings for the trailer I cannot see any problems you would run into. Regarding sway, that comes down...
    view full answer...
  • Can the Curt Trailer Hitch Handle a 1,000 Pound Trailer Towed With a 2021 Corolla Hatchback
    The Curt Trailer Hitch Receiver - Custom Fit - Class I - 1-1/4" # C11567 has a maximum gross trailer weight of 2,000 lbs and tongue weight of 200 lbs. This means it will be able to handle towing your 1,000 lb trailer without any issues. I would also make sure to consult the owner's manual so you know the towing capacity of your vehicle. You will be limited by whichever is lower, the vehicle or hitch capacity. Since you will be towing a trailer you will also need wiring. I recommend the...
    view full answer...
  • Complete Towing Setup for a 2018 Toyota Corolla iM
    I have exactly what you will need to tow your small john boat to the lake with your 2018 Toyota Corolla iM. For starters you will need a trailer hitch and for that I recommend the Draw-Tite Sportframe Trailer Hitch Receiver part # 24952. The Draw-Tite Sportframe is a Class I hitch with a 1-1/4" receiver tube opening. I have attached an installation video of this hitch installed on a similar 2017 Toyota Corolla iM for you which as you can see is very simple and straightforward. Then if...
    view full answer...
  • How To Carry Motorcycle on 2016 Scion iM
    The trailer hitch options for a 2016 Scion iM like the Draw-Tite Sportframe Trailer Hitch Receiver part # 24952 max out at 2,000 lbs gross trailer weight and 200 lbs tongue weight. If the hitch mounted carrier you want to use exceeds the above tongue weight capacity you will need to transport said item on a trailer using the following: T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # 118729 Draw-Tite Drawbar part # 3593 Hitch Ball part # 19256 or part # 19258 Please...
    view full answer...
  • Recommended Hitch for a 2021 Toyota Corolla Hatchback Hybrid
    For your 2021 Toyota Corolla Hatchback Hybrid, you will want to use the Curt # C11567. This will fit all models of the Corolla Hatchbacks. I included a video we did of an install we did on a 2020 for you to check out as well. I also included a Tekonsha 4 Flat Harness # 118729, with an install video as well, in case you were planning to tow with the hitch. If you were planning to tow your Corolla behind an RV, however, you will need other parts to get it set up. From what I could find out...
    view full answer...
  • Trailer Hitch Installation for 2022 Toyota Corolla Hatchback
    We don't have footage of the Curt # C11567 Class I hitch being installed on a 2022 Corolla hatchback but we do have a video of it being installed on a 2020 model, see the link. I've spoke with my contact in the engineering department at Curt, who tells me that the procedure for installing the hitch on a 2022 model would be the same as the 2020 model shown in the linked video. If you'll also be using the hitch for light duty towing, you'll also need a trailer wiring harness like # 118729,...
    view full answer...

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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Cole B
Installed by:
Cole B
Employee Chris R
Video Edited:
Chris R
Employee Wilson B
Updated by:
Wilson B
Employee Isabelle B
Updated by:
Isabelle B
Employee Alexander C
Written by:
Alexander C
Employee Zach D
Video by:
Zach D
Employee Shane H
Test Fit:
Shane H

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