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FITS 2017 Chevrolet Sonic
T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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

Item # 118755
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Custom Fit Vehicle Wiring
Confirmed to Fit
2017 Chevrolet Sonic

LS models

LT and Premier

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Tekonsha Trailer Hitch Wiring - 118755
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Call etrailer.com at 800-298-8924 for expert service. We are your Chevrolet custom fit vehicle wiring experts, and offer a lowest price guarantee. etrailer.com carries a complete line of Tekonsha products for your Chevrolet Sonic 2017. T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part 118755 from Tekonsha can be ordered online at etrailer.com. Complete custom fit vehicle wiring installation instructions and technical support.
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  • Reviews (6)
  • Q & A (1)
  • Videos (1)
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2017 Chevrolet Sonic - T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

  • Trailer Hitch Wiring
  • Tekonsha
  • 4 Flat
  • Powered Converter

Quickly and easily install a 4-way trailer connector on your Chevrolet Sonic 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 behind the driver's-side and passenger's-side interior trim panels in your trunk. You will need to remove 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 trunk.

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.

118755 Tekonsha T-1 T-Connector - 4 Wire - Modu-Lite

Installation Details 118755 Installation instructions

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 - 118755 Review

Speaker 1: Today we're going to be taking a look at the T1 vehicle wiring harness with the four pole flat trailer connector. This product fits certain years and models of the Chevrolet Sonic. To ensure that this is a fit for your vehicle, you can use the Vehicle Fit Guide located at etrailer.com.Now this provides a four-way flat connector at the back of your vehicle to power your trailer signal lights. It is compatible with five pole, six pole, and seven 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 your connection points when the plug's not being used. This dust cap is actually tethered to the plug housing so you don't have to worry about misplacing that or losing it.The black box is the included ModuLite. This ensures that your vehicle's wiring matches out of your trailers. This powered module connects directly to the vehicle battery through the wiring to avoid overloading your vehicle's electrical system.Now it is designed to connect quickly and easily. All you need to do is locate the connection points in the rear cargo area, and plug in your connectors.

One goes to the passenger side, the other one goes to the driver's side of the vehicle.Now these plugs are custom fit for your vehicle, so they are vehicle-specific. They're going to match up perfectly with the ports on the vehicle, and they're going to snap lock together for a nice tight secure fit. So once you have those connected, you'll need to make a ground connection. Your ground wire is your white wire with the ring trim roll attached to it. You want to get this grounded at a suitable grounding location with the included grounding screw.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 included double-sided adhesive foam tape.

Then 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 15 amp fuse, goes directly in the fuse holder.

That'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 your wiring with the included cable ties, and once your install's complete, the four-way connector's going to be stowed in your trunk. You got plenty of wire in 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 in the vehicle and the four pole connector itself. That grease is specifically designed to help prevent corrosion to the connection points. It is sold separately and available at etrailer.com.When it comes to the maximum amperage for the stop and turn lights, we're looking at 5 amps per circuit, and for the tail lights, we're looking at 7.5 amps per circuit.That's gonna do it for today's look at the T1 vehicle wiring harness with the four pole flat trailer connector.

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118755

Average Customer Rating:  4.8 out of 5 stars   (6 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.

- 118755

Am studying the pictures, directions, watched the video & figuring out the wiring this week before going for it ! Will update when completed but so far looking good... Thanks. 906835

- 118755

Easy hookup 873183

- 118755
2004 Chevrolet Sonic

Really great quality....I purchased this wiring set up because the factory wiring on my Sonic is only big enough for its own lights and I want to pull a small trailer....This Curt product uses power straight from battery...This unit does exactly what I wanted.... 794651

- 118755

just what I was looking for something easy to install 756886

- 118755

Extremely happy with the product after one year, very easy to install (connect). All good! 653549

- 118755
2017 Chevrolet Sonic

Crazy that car companies don't have a trailer hook up in their wiring harness or a hot lead to the back so you are forced to buy this product. Unit works as it should first time, no issues. What was really helpful was the etrailer video installing the unit in a 2015 Sonic which is very close to the 2017. The video is something that should be referenced on the sales page for every model year - "Look at 2015 video". That video gave me hints to do the installation with no hesitation. I had my laptop on the bench and paused the video as it stepped through the process. I ran the hot lead on the inside like the video, tucking it in like it showed. What took some screwing around was pushing the hot lead through the squishy big rubber grommet in the fire wall. I had to make the slit in the rubber much larger than I thought it should be. The install took a couple hours but no worse than installing a CD player or driving lights for those that remember the old days. What makes etrailer great is the installation videos, how-to and troubleshooting how-to pdf's and product selection. The hitch I bought for the '17 Sonic took like 20 minutes to install - again the video gives you the confidence. The only thing better would be free shipping for $50 minimum - HINT. Thanks for asking..... 549207

Working great. Your video was crucial to the installation.
HandyHusband01 - 08/03/2019


Ask the Experts about this Tekonsha Custom Fit Vehicle Wiring

  • Comparing Trailer Wiring Harnesses for a 2017 Chevrolet Sonic RS/LT Hatchback
    You are correct in that both the T-One Vehicle Wiring Harness part # 118755 and the T-Connector Vehicle Wiring Harness part # C56372 are a fit for your 2017 Chevrolet Sonic RS/LT Hatchback. There are few differences between them as they both plug in behind the tail lights without any cutting or splicing involved. They are essentially just two different manufacturers version of the same product. They both have the same purpose and will plug into the same connector on the vehicle which is...
    view full answer...

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Info for this part was:

Edited by:
Lindsey S
Installed by:
Cole B
Updated by:
Sarah W
Updated by:
Isabelle B
Written by:
Alexander C

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