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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 # 118773
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Custom Fit Vehicle Wiring

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Tekonsha Custom Fit Vehicle Wiring - 118773
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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. Call 800-298-8924 to order Tekonsha custom fit vehicle wiring part number 118773 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 (4)
  • Q & A (8)
  • Photos
  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118773

  • 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.


  • 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 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 behind the driver's-side and passenger's-side tail lights. You will have to remove the floor trim panels, access panels, and 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 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.

118773 Tekonsha T-1 T-Connector - 4 Wire - Modu-Lite

Installation Details 118773 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 - 118773

Average Customer Rating:  4.8 out of 5 stars   (4 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.

- 118773
2018 Volvo XC60

This harness is almost perfect. One gripe is that the instructions say to install this on the drivers side rear compartment. I don't know why anyone would want to do that. The factory harness kit attaches on the passenger side, the gasket to pass wires through the body is on the passenger side, and there is a fuse box with 12V stud as a spare grounding stud for the factory trailer wiring. Installing it on the drivers side would require lengthening the trailer 4 pin wires and stringing a longer power back across the vehicle. So I installed on the passenger side. My complaint with that is the yellow/brown wires going to the drivers side taillight is too short to reach across the vehicle, so I had to splice in a wire to extend it. Making the inline wires the same length as the passenger side would have made this a perfect wiring kit allowing install on either side of the vehicle. Like the hitch, I referred to the Volvo hitch/wiring harness install for details on body removal, and existing wiring details. (Google Volvo Instruction No 31454723 for Part No 31439424). When you remove the passenger side panel, there is a circuit breaker box and two factory connectors covered in a small bag. These are the connectors for the factory wiring harness module. If you add a breaker in the spare slot between the existing 40A and 20A breakers, this will provide power (always hot) to the Red/Brown wire on the 2 wire power connector. I terminated the black wire from the Tekonsha module with a spade crimp which fit right into the connector (could have cut off the factory connector and just spliced the wire, but decided against that). Taped and secured the connection to make sure it doesn't separate over time. I added a 20A fuse since that was the smallest amperage I could find at the auto parts store (factory module comes with a 40A fuse but the power plugs right into their module, and Tekonsha kit came with a 15A fuse). I originally installed the 4 pin connector to the left of the hitch receiver. When I started to trim the bumper fascia, I realized the sensor to open the tailgate with your foot was in the way, so had to move it to the right side of the receiver. 592921

- 118773

Product was easy to install. The adaptor box gits nicely in the spare tire compartment, along with the connector. It was great for my occasional use of a trailer. A great pairing with the hitch for the bicycle rack 809306

- 118773

Trailer wiring kit has worked flawless for more than a year. I am very satisfied. 803035

- 118773
2018 Volvo XC60

Perfect fit for my 2018 Volvo XC60. Getting access to the tail lights was the most difficult part. Installation took one hour. The instructions included show the battery in the engine compartment, but my vehicle has the battery in the spare tire compartment under the cargo area. No need to route the black 12 ga. power wire forward under the vehicle. Bonus! Tested the 4-Flat connector and good to go. 636941


Ask the Experts about this Tekonsha Custom Fit Vehicle Wiring

  • Location of Plugs to Install Trailer Wiring Harness on 2020 Volvo XC60
    It sounds like you're trying to install a wiring harness like the Tekonsha # 118773, and the plugs you're looking for are located behind the trim panels in the cargo area on the driver and passenger side. I've linked the instructions for this harness that show where these are located as well as added a photo that one of our customers sent in that shows what that area looks like when the covers are removed.
    view full answer...
  • Does Trailer Hitch Receiver for 2019 Volvo XC60 Interfere With Hands-Free Liftgate
    It is possible that the Draw-Tite Trailer Hitch Receiver # 76194 for your 2019 Volvo XC60 will interfere with the hands-free liftgate feature. Many times with hitches you only need to kick your foot to either side of the receiver for it to work but with this hitch it is possible you may lose the hands-free feature. I have added a link to a video install for you to check out as well of the Draw-Tite Trailer Hitch Receiver # 76194. Additionally, if you plan on towing and need trailer...
    view full answer...
  • Finding Someone to Install Trailer Hitch on 2019 Volvo XC60
    Since we aren't familiar with your area the best solution I can give you for finding someone to install the Draw Tite Hitch # 76194 and wiring kit part # 118773 on your 2019 Volvo XC60 is to check with mechanics and garages near you that have solid reputations. Hitch installs are very basic for mechanics based on what they normally work on so the install does not take a specialist by any means at all.
    view full answer...
  • Installing Tekonsha T-One Vehicle Wiring Harness on 2019 Volvo XC60
    The Tekonsha T-One Vehicle Wiring Harness # 118773 plugs into factory ports behind the driver and passenger side tail lights. To access the connection points on your Volvo XC60 you should just need to remove the floor trim panels and access panels inside the rear cargo area (see attached image). It might take a bit of digging but the factory harness will then be located inside the access panel area. If you are still having trouble find the harness please let me know and I will be happy...
    view full answer...
  • Draw Tite Hitch that Fits 2020 Volvo XC60
    The Draw Tite hitch part # 76194 that you referenced is a confirmed fit for your 2020 Volvo XC60 with or without air suspension. There also isn't any special fascia trimming required for the R models either. For trailer wiring the Tekonsha kit # 118773 would then be a great choice as well as it installs easily and is very reliable.
    view full answer...
  • Recommended Trailer Hitch for 2018 Volvo XC60
    We sure do! For your 2018 Volvo XC60 I recommend the Draw-Tite Class III Max Frame Receiver Hitch # 76194. The hitch will use existing holes in the Volvo's frame for a no-drill installation and features a nice hidden design where only the receiver is visible behind the vehicle. This is currently the only hitch available that is confirmed to fit your vehicle. It has a towing weight capacity of 6,000 pounds and a tongue weight limit of 900 pounds. You will also want to verify the towing...
    view full answer...
  • Ground Clearance With Draw-Tite Trailer Hitch Receiver 76194 Installed On 2021 Volvo XC60
    Luckily we have the exact measurement you are looking for. When we installed the Draw-Tite Max-Frame Trailer Hitch Receiver # 76194 on a 2020 Volvo XC60 we found that from the bottom of the safety chain loops to the ground is 9", and from the bottom of the receiver tube to the ground is 11" as shown in the included diagram. The Draw-Tite # 76194 is a great option for your 2021 Volvo XC60 as it is a very strong trailer hitch receiver that has a maximum tongue weight rating of 900lbs,...
    view full answer...
  • Trailer Hitch Recommendation for 2018 Volvo XC60
    For your 2018 Volvo XC60 we have the really great option from Draw Tite part # 76194. This hitch has a concealed crosstube which allows it to be mostly out of plain sight and has great towing capacities at 6,000 lb trailer weight. Then for wiring we have the T-One kit part # 118773 which is a custom fit and uses the most reliable converter box so I recommend it highly. If you wanted to do some towing you might be interested in etrailer ball mount kit # 989900. It comes with 2 ball...
    view full answer...

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Info for this part was:

Edited by:
Lindsey S
Installed by:
Jeff D
Video Edited:
Jacob T
Updated by:
Sarah W
Updated by:
Isabelle B
Written by:
Alexander C
Test Fit:
Conner L

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