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

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

Item # 118742
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Custom Fit Vehicle Wiring

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T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector Powered Converter 118742
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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 - no cutting, splicing or tapping required. Powered ModuLite reduces strain on wiring system. 1-800-940-8924 to order Tekonsha custom fit vehicle wiring part number 118742 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 (11)
  • Q & A (0)
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  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118742

  • 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 - no cutting, splicing or tapping required. 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 have to remove the rear threshold and felt trunk liner 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.

118742 Tekonsha T-1 T-Connector - 4 Wire - Modu-Lite Converter Included

Installation Details 118742 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 - 118742

Average Customer Rating:  4.8 out of 5 stars   (11 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 - no cutting, splicing or tapping required. Powered ModuLite reduces strain on wiring system.


Very good quality and easy to use. Hade my body shop install and they had no issues.


Did not match the vehicles plug. Had to have an electronics shop cut and wire into my car.(2020 VW Passat)

For the 2020 Volkswagen Passet there are two options for the vehicle - it either comes with LED tail lights or incandescent tail lights. This harness is for vehicles that came with LED lights. For the Passet that does not come with LED lights you would need part # 118721
T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
. The connectors will be different depending on what you have.
-- Etrailer Expert Jenny N - 01/31/2022


Easy to install not much tools required fit perfectly great product at a great price

2017 Volkswagen Passat

I installed this Draw-Tite hitch on my 2017 VW Passat SE by myself. The hitch is heavy and well built. I followed the instruction videos which where very helpful. My 2017 passat has a rather large plastic shroud that had to be trimmed and made the job just a bit more time consuming, but not impossible. Measuring and trimming could have been more tidy on my part but I wanted the shroud to have extra room for reinstalling.
I was more precise when measuring for the two drilled holes allow the center brace bolts to fit through the shroud.
Tip: Harness 117842, when unplugging the left and right wires for the trailer lighting harness, pull the red clip out the depress the locking tab to disconnect the OEM plugs. Running power from the battery was the most time consuming.


The product was a little difficult to install only because of running the hot wire from the back of the car to the front in my vehicle. However, other than that one thing, the product has worked fine, and I would recommend it to anyone. I could have taken short cuts and got it done quicker, but it looks professional done as the instructions say.


was very knowledgeable and
helpful throughout the whole ordering process.
she googled and verified with her vender to make sure the order matched my Volkswagen. I have never installed a hitch on a car before and was very worried if I was going to get the right things.
She even emailed me letting me know my that my order was delivered to my door this afternoon.

If you call and order as for NATALIE.


Have received product but have not installed it yet.

2012 Chevrolet Volt

Everything fit as advertised. Hardest part was running 12 volt wire to the trunk.


worked like it should


great product and super fast delivery



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

  • Troubleshooting Harness on 2016 VW Passat SE
    It is almost certainly not a bad module, and I'm not quite sure what you mean by "reinitialize" although I can offer you some basic troubleshooting tips, as there could be any number of potential issues with the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118742 on your '16 Passat SE. In order to determine the specific problem you will need to use a circuit tester and test the connector on your vehicle after disconnecting it from your trailer. You mentioned you have...
    view full answer...
  • Does Draw Tite Hitch # 24880 Fit 2017 Volkswagen Passat SEL with Technology Package
    Yes, the Draw Tite hitch part # 24880 that you referenced does fit your 2017 Volkswagen Passat SEL with the technology package. However, the hitch will interfere with the Hands-free Easy Open Trunk option and functionality may be very limited or possibly lost. You'll run into the same issue with the Curt and EcoHitch trailer hitches that fit your 2017 Passat SEL as well. If you need trailer wiring you'd want the Tekonsha kit part # 118742 which is a confirmed fit and is also compatible...
    view full answer...
  • Needing a Wiring Harness to Fit a 2017 Volkswagen Passat SE
    I have the answer for you. For your 2017 Volkswagen Passat the Tekonsha T-One Wiring Harness, # 118742, is the confirmed fit for your SE model. The connector will plug in to your Passat's factory wiring and will provide a 4-pole flat connector for your vehicle. The harness will include a ModuLite convertor that will ensure that your Passat wiring will match the trailer you will be wanting to tow.
    view full answer...
  • Correct Trailer Wiring Harness for a 2017 Volkswagen Passat SEL with LED Taillights
    The correct T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector for your 2017 Volkswagen Passat SEL with LED taillights is part # 118742, not part # 118721 which is for the S model.
    view full answer...
  • How to Find Out if a 2016 Volkswagen Passat SE has a Towing Capacity and How Much It Is
    If your 2016 Volkswagen Passat SE has a towing capacity it would be listed in the vehicle owner's manual. Volkswagen used to provide access to the owner's manuals online but now in order to view the manual online you have to put in a valid VIN for that vehicle. But your owner's manual would be the place to check for towing information. If you decide to go with Draw-Tite trailer hitch # 24880 the recommended ball mount is # 3590. For a compatible ball you can use # 19256 for a 1-7/8 inch...
    view full answer...
  • Does the Tekonsha T-One Vehicle Wiring Harness and Connector 118742 Come With a Mounting Bracket
    The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118742 does not come with a mounting bracket. You can use the Mounting Bracket # 18144 as well as a No-Drill Mounting Bracket Short # 18140 or Long # C57202 for an easy installation that does not require you to drill into your trailer hitch receiver. I have attached a video of these two products being installed that you can reference.
    view full answer...
  • How to Determine Towing Capacity of 2018 VW Passat
    The best way to determine what your vehicle can tow is by looking at its owner's manual. Unfortunately, VW manuals are hard to find online unless you own the car already so I don't have a way to look at it for you. From the research I did it seems that the max towing capacity of your 2018 Passat is 1,000 pounds which sounds pretty likely. I recommend checking your manual to be certain though. Once you know how much you can tow you'll need the parts to do it. The hitch I recommend is...
    view full answer...
  • Recommended 4-Way Trailer Wiring Harness to 7-Way Trailer Adapter and No Drill Mounting Bracket
    The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118742 for 2016 - 2018 Volkswagen Passat SE and SEL models will connect to a 7-way using an adapter like the Hopkins Adapter 4-Pole to 7-Pole and 4-Pole # 37185. You simply will connect the 4-way trailer connector and then ground the adapter to your vehicle using the white wire with ring terminal. If you want the other 7-way functions, you will need to use a kit like # 5506 to add the 12V power and brake controller....
    view full answer...
  • Hitch Recommendation for 2019 VW Passat With Easiest Install Process
    If it were my Passat, I would go with the EcoHitch # 306-X7317 because of the options it gives for accessories. The install is more involved than others, but I think this is the best choice. You'll only install the hitch once, but you will use it for much longer and will find the extra effort is well worth it. There are 3 different hitches that are confirmed to fit your 2019 VW Passat Wolfsburg edition, Draw-Tite Sportframe Trailer Hitch # 24880, the Curt Trailer Hitch Receiver # C11234,...
    view full answer...
  • Will Hands-Free Trunk Feature on 2017 VW Passat Affect Installation of EcoHitch 306-X7317
    Although the EcoHitch could interfere with the hands free trunk feature on you 2017 VW Passat or possibly prevent it from working, the fact that the vehicle has that feature won't affect the fit of the # 306-X7317 EcoHitch. The install is pretty involved, as you can see from the video I've linked for you. If you'll be using the hitch for towing purposes, you'll also need a trailer taillight wiring harness like # 118742 if the vehicle has LED taillights or # 118721 if it has incandescent...
    view full answer...
  • Hitch Fit for 2020 Volkswagen Passat
    According to Curt, their # C11234 will fit all models of the 2020 Passat, with the exception of models equipped with the hands-free truck feature. If you'll be using the hitch for light-duty towing, you'll also need a trailer wiring harness like # 118742, a ball mount like # C45521, a hitch pin like # PC2 and a 1-7/8 inch hitch ball like # A-80 or a 2 inch ball like # A-82. I've linked to an install video for the hitch.
    view full answer...
  • Recommended Hitch and Towing Accessories for 2019 Volkswagen Passat
    For what you're using the hitch for, you'd be fine with a low-cost option such as the Draw-Tite Class I receiver, part # 24880 but if you were planning on also using the hitch as a mounting location for a bike rack or a cargo carrying tray, you might be better off going with a 2 inch receiver like what would be provided by the EcoHitch # 306-X7317. There are many more accessory options that are compatible with a 2 inch receiver, so if you were going to use the hitch for something other...
    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 Wilson B
Updated by:
Wilson B
Employee Isabelle B
Updated by:
Isabelle B
Employee Alexander C
Written by:
Alexander C

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