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

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

Item # 118754

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Tekonsha Trailer Hitch Wiring - 118754
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  • Custom Fit
  • Trailer Hitch Wiring
  • Tekonsha
  • 4 Flat
  • 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. Call 800-298-8924 to order Tekonsha custom fit vehicle wiring part number 118754 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.

  • All Info
  • Reviews (10)
  • Q & A (16)
  • Videos (1)
  • Photos
  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118754

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 point 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
  • Limited 1-year warranty


This custom-fit T-One connector plugs into your vehicle's wiring harness, which is located in your rear cargo area. You will have to remove the threshold cover, 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 multiplex-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.

118754 Tekonsha T-1 T-Connector - 4 Wire - Modu-Lite

118754 Installation InstructionsInstallation Details 118754 Installation instructions

This Product Fits The Following Vehicles

2018 - 2019 Volkswagen Atlas

2018 - 2019 Volkswagen Atlas

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 Tekonsha Custom Fit Vehicle Wiring - Trailer Hitch Wiring - 118754 Review

Speaker 1: Today we're taking a look at a T-One Vehicle Wiring Harness with the 4-Pole Flat Trailer Connector. This product fits certain years of the Volkswagen Atlas. To ensure that this is a fit for your vehicle, you can always use the vehicle fit guide located at etrailer.com. This unit provides a four-way flat connector at the back of your vehicle to power your trailer signal lights. It is compatible with 5-pole, 6-pole, and 7-pole adapters adapters are sold separately and it comes with a dust cap for the four-way flat connector. That way you can cover up the connection points when your plug's not being used.The black box on the unit is the included ModuLite.

This ensures that your vehicle's wiring matches that of your trailers. This powered module connects directly to the vehicle battery through the wiring to avoid overloading your vehicle's electrical system. Now, the unit is designed to connect quickly and easily. All you need to do is locate the connection points in the rear cargo area, and then you're going to have two connectors: one favors the driver's side, the other one goes to the passenger side. These are custom-fit for your vehicle, so they're going match up perfectly with the ports on the vehicle, and they're going to snap lock together for a nice, tight, secure fit.So you get those plugged in, then you'll need to make a ground connection.

That's your white white wire with the ring terminal attached to it. You want to get that grounded to a suitable grounding location, and you can use the included grounding screw to do that. And then you'll need to mount the converter box to a safe, out-of-the-way location, and you can do that using the double-sided adhesive foam tape provided in the kit.Next, you'll need to run the hot lead to the vehicle battery. The hot lead is the short, black wire coming out of the box. This gets connected to one end of the bundle with one of the included butt connectors.

The other end of the bundle runs to the vehicle battery, gets another butt connector attached to it, and connects to one half of the fuse holder. The other half of the fuse holder gets a ring terminal attached to it and connects to the positive post of the vehicle battery. It does come with your 15A fuse, it goes directly in the fuse holder, and it's got the cap that goes over it to keep it safe and protected.Once you have that done, you can secure any excess or slack in the wiring with the included cable ties, and then once your install is complete, the four-way flat connector will be stowed in your rear cargo area. Plenty of wiring here, so you can extend it out the back when you need to use it. Roll it up and tuck it away when you don't.

It is recommended that you use a small amount of dielectric grease in all your electrical connections, like the plugs on the vehicle, and the 4-pole connector itself. That grease is specifically designed to help prevent corrosion. It's sold separately and available at etrailer.com. When it comes to the maximum amperage for the stop and turn lights, we're looking at 5A per circuit, and for the tail lights, we're looking at 7.5A per circuit. The unit also comes with detailed installation instructions to help walk you through the entire process step by step.That's going to do it for today's look at the T-One Vehicle Wiring Harness with the 4-Pole Flat Trailer Connector.

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118754

Average Customer Rating:  4.1 out of 5 stars   (10 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.

- 118754
2018 Volkswagen Atlas

Kit was very good, except that 4 conductor connector cannot be fed through existing opening in spare tire tray and must be cut. An enhancement would be to allow the connection of the 4 conductor lead to the 'control box' with a narrow connector that can be snaked through the existing rubber plug in spare tire tray. Additionally the length of wire for the 4 conductor plug is too short. Resolved by purchasing another connector with wire and splicing. Plug compatible installation for taillight harness is great. 496282


Tekonsha purposely designs the wiring harness to be stored in the interior of the vehicle when it is not being used so that the trailer connector is protected from the elements. When the trailer connector is needed, it can easily be ran out the back of the vehicle, and the trunk or hatch lid can be closed on the wiring. The rubber gasket on the hatch is plenty thick enough to protect the wires, as long as you keep the wires away from the latch. Ive towed my PWC trailer for years this way with my van, and it works great.

-- Mike L - 04/14/2018


- 118754

If you want plug and play you might as well spend $300 on the one from VW. In order to get what I would consider a proper install it took about 2.5 hours. The included instructions are 100% useless. Here are a couple notes: 1. If you run the hot wire underneath like the instructions say you will probably end up drilling a hole in the spare tire well to get it inside. You can run it inside under the kick panels he whole way back if you go through the main harness grommet in the fire wall. 2. Unless you want wires showing inside the back of your new car where this runs from one tail light to the other, you will either have to remove every interior panel in the back of your car (I couldn’t even figure out how) or cut this harness apart, fish the wires, and splice it back together. Bottom line is, unless you are pretty mechanically capable you will either pay to have someone do this right or have wires strung all over the inside of your new Atlas. The only reason I gave this 2 stars is for the price. 609999

- 118754

The wiring harness worked perfectly. No complaints. 697599

- 118754

Fits with out cutting or modifying anything. Took awhile to figure out how to fish the bracket and bolt through the frame rail but after the 1st 1 the rest went quick. Would recommend and purchase again! 696576

- 118754
2018 Volkswagen Atlas

Just as promised on time delivery. Top notch service. 667044

- 118754
2018 Volkswagen Atlas

Exact fit for my car (2018 VW Atlas) with easy to follow instructions that were vehicle specific. Supplied power wire (runs from battery to brain box) actually long enough to reach both! Trailer tail lights are brighter than when they leach off the tail light power due to the direct battery supply. Overall very pleased. 643505

- 118754

Electrical unit was easy to install. Great directions and fit perfect. 598209

- 118754

If you have a 2018 Atlas, do not get this. The t-connectors work just fine, however the instructions are incredibly vague and provide you with no information on how to hide the wires inside the trim panels. There is also no mention on how or where to get the black power wire to the underbelly of the car. Finally, the black power wire provided is not long enough to reach from the back to the front battery. Major design flaw. I would not buy this if I were you. When I brought up these issues the expert told me the instructions were vague on purpose because it is supposed to work with multiple vehicles. However, the instructions that came with the wiring had 4 pictures specific to the Atlas and it also had Volkswagen Atlas printed on the instructions. The truth? The instructions are incredibly vague. I doubt anyone has even installed this successfully on a 2018 Atlas. Do not buy. 522251

- 118754
2018 Volkswagen Atlas

easy plug and play install. directions easy to follow. 518820

- 118754
2018 Volkswagen Atlas

Great! 444772


Ask the Experts about this Tekonsha Custom Fit Vehicle Wiring

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

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Info for this part was:

Edited by:
Lindsey S
Expert Research:
Michael H
Expert Research:
Jameson C
Installed by:
Cole B
Written by:
Alexander C
Updated by:
Isabelle B

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