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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 # 118590
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Custom Fit Vehicle Wiring

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Tekonsha Trailer Hitch Wiring - 118590
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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 118590 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 (7)
  • Q & A (0)
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  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118590

  • 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 trunk
    • 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: 2.1 amps per circuit
    • Tail lights: 5.6 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 trunk, behind the tail lights on both the driver's side and passenger's side. You will need to remove some interior trim or carpeting to access the 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.

Once installation is complete, the 4-way flat connector will be stowed within 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.

118590 Tow Ready T-1 T-Connector - 4 Wire - Modu-Lite

Installation Details 118590 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 - 118590

Average Customer Rating:  5.0 out of 5 stars   (7 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.


Easy install

2018 Chevrolet Impala

Easy to install.

Great. Working as it should. Great product.
Luis - 02/17/2020

2020 Chevrolet Impala

I’ve done these before, everything you need is included.


Everything I needed, and easy to instal l.

2019 Chevrolet Impala




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

  • Does Trailer Wiring Power Wire for 2014 Chevy Impala have to be Routed to Battery a Certain Way
    There is no one specific way that the power wire has to be run for trailer wiring harness # 118590 for your 2014 Chevy Impala. Running it through the interior of the vehicle takes the longest, and you may need additional wire, but it also offers the most protection. I have included a link to a help article I wrote with tips on routing the power wire.
    view full answer...
  • Installing Tekonsha 118590 Trailer Wiring Harness on 2014 Chevy Impala
    In order for the Tekonsha # 118590 wiring harness to function, it will need to draw 12V power from the battery as shown in the linked installation instructions. The harness's inline connection to the vehicle's taillight harness provides switching information, but won't supply the power necessary to drive the trailer taillights. The only two bare wires on the harness assembly are the red and the white. The white is the ground connection, which needs to be attached to the vehicle chassis...
    view full answer...
  • Concealed Cross Tube Hitch Recommendation For 2019 Chevy Impala Premier
    I do have a hitch option for you for the 2019 Chevy Impala Premier but there is not an option available for this vehicle that is completely hidden when not in use. I recommend to use the Curt Trailer Hitch Receiver part # C12115 which is a concealed cross tube design so the only part of the hitch visible once installed is the receiver. The Curt hitch will give you a 1-1/4" receiver on the back of the Chevy and the cross tube will be hidden behind the bumper which is the most discreet...
    view full answer...
  • Recommended Trailer Hitch and Transmission/Oil Cooler for 2019 Chevy Impala
    Starting with the hitch I recommend the Curt Class II Receiver # C12115 because it features a slightly higher tongue weight capacity (350 pounds) than the Draw-Tite model also available for your Impala and is made right here in the USA. It features a 3,500 pound towing weight limit and will use existing holes in the vehicle's frame for a no-drill installation. I have attached an installation video that you can use for reference. I do recommend verifying the towing capacities of your...
    view full answer...
    Image 1 for
  • Hitch Recommendation for Towing a Trailer on a 2015 Chevy Impala
    If you have a Class I 1-1/4" compatible trailer, you can use a Class II 1-1/4" hitch receiver. The only difference between the two classes is that the Class II has a greater overall weight capacity than a Class I hitch. I went ahead and attached a helpful chart that shows the differences between these hitch classes. For a great option to accommodate the trailer on your 2015 Chevy Impala, I recommend the Curt Class II - 1-1/4" # C12115. This hitch not only provides you with 350 pounds of...
    view full answer...
    Image 1 for
  • Towing Capacity and Trailer Hitch Recommendation for 2017 Chevy Impala
    From what I found online it looks like your 2017 Chevy Impala has a towing capacity of 1,000 lbs. If the weight of your trailer loaded is less than 1,000 lbs then yes you could tow it. For a hitch then we have the Draw Tite part # 36538 which is a confirmed fit for your vehicle and would work well. For a ball mount you'd then want the # 36061 which is the recommended ball mount by Draw Tite. For a hitch ball part # 19257. For trailer wiring you'd then want the Tekonsha kit part # 118590...
    view full answer...
  • Recommended Trailer Hitch Receiver for 2017 Chevy Impala Premier
    The Impala Premier models do have a similar fit to the other models. I recommend the Draw-Tite Trailer Hitch Receiver # 36538 for your 2017 Impala Premier which is a confirmed fit. It is a Class II hitch receiver that will give you the support needed and allow for the dual exhaust pipes. If you will be towing, I recommend the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118590 which installs behind your tail lights. You will then run a wire to your battery to power...
    view full answer...
  • Does Hot Lead Have to be Run to Battery When Installing Wiring Harness
    You should run the hot lead to the battery when installing a 4-way in your 2016 Chevy Impala, no matter which one it is: the Tekonsha # 118590, Curt # C56188 and Hopkins # HM11141434. I took a look at the instruction manual for each and they all specified running the hot lead to the battery in the engine compartment. The reason for that, this is the only way to ensure your car's wiring and electrical systems are not otherwise damaged. You will find in the linked directions of all three...
    view full answer...
  • Trailer Hitch and Wiring Recommendation for 2014 Chevy Impala
    We have hitches that fit your 2014 Chevy Impala like the Draw Tite Class II hitch part # 36543 which is what I recommend. It installs easily and also gives you a mostly hidden solution. This is a bolt on hitch that does not require any welding. For trailer wiring our most reliable option is the Tekonsha # 118590 which I recommend for you. For a ball mount the # 36061 is the required part number and then for a ball # 19257.
    view full answer...
  • Trailer Hitch and Wiring for a 2015 Chevy Impala LTZ
    Your assessment of the trailer hitches for the 2015 Chevy Impala LTZ are correct. Curt trailer hitch # C12115, Draw-Tite hitch # 36538, and Hidden Hitch # 90242 (no longer available) all install in a similar fashion at the same places. the Draw-Tite and Hidden Hitch models even share the same instructions. Quality wise all of the hitches meet or exceed industry standards. Some people tend to like the finish on the Curt hitches better. All three of these hitches fit both LT and LTZ models...
    view full answer...
  • Recommended Trailer Hitch For 2014 Chevrolet Impala LTZ
    The Curt Trailer Hitch, part # C12115 is confirmed as a fit for your Impala. This is a Class ll hitch and it has a 1-1/4 inch receiver opening. Per Curt, all non-trailer loads - bike racks, cargo carriers and so forth - should be supported with stabilizing straps like part # 18050. Failure to properly support these loads will void your hitch warranty from Curt. For that reason I recommend going with the Draw-Tite Trailer Hitch, part # 36538. This is also a Class ll hitch and it does not...
    view full answer...
  • Trailer Hitch and Wiring for a 2014 Chevy Impala LT
    For your 2014 Chevy Impala LT I recommend Curt trailer hitch # C12115 with ball mount # C45017. This hitch is rated for a maximum of 350 pounds tongue weight and 3,500 pound gross trailer weight. Check the Impala owner's manual for its capacity and go by the lower of the two. For a 1-7/8 inch ball use # 19256 and for a 2 inch ball use # 19258. Please note the 1-7/8 inch ball is rated for 2,000 pounds gross trailer weight. You also need # F-4 for a pin and clip. For a trailer wiring harness...
    view full answer...
  • Recommended Trailer Hitch And Trailer Wiring For 2017 Chevrolet Impala Premier
    I recommend the Draw-Tite # 36538 trailer hitch for two reasons. First, the Curt hitch # C12115 requires trimming of the underbody trim panel. And second, the Curt hitch requires the use of a stabilizing strap like part # 18050 when using the hitch for any non-trailer items like bike racks and cargo carriers. Both trailer hitches are visible, but the Curt hitch may be a little less visible because of the underbody trimming. The # 36538 hitch requires no drilling for installation. This...
    view full answer...
  • Trailer Hitch for 2019 Chevy Impala and Recommended Ball Mount, Hitch Ball and Wiring
    There is a trailer hitch for your 2019 Chevy Impala; I highly recommend the Curt # C12115 because it is a bolt-on installation that will not require drilling into your Impala's frame to install. This Class II, 1-1/4" trailer hitch has a black powder coat finish which helps protect it from corrosion and also has a 3,500 lb towing capacity and 350 lb tongue weight capacity, though I did check the owner's manual and it states the maximum weight your Impala can tow is 1,000 lbs so that is...
    view full answer...
    Image 1 for
  • Recommended Trailer Hitch and Towing Accessories for 2014 Chevy Impala LTZ
    The Draw-Tite # 36543 would be a fine choice that would work great for you, however I'd personally choose the Curt # C12115 because the hitch itself is manufactured in the USA and its one of the least expensive options. It also has a higher tongue weight capacity at 350 lbs versus 300 lbs for the Draw-Tite. For wiring, I'd personally choose the # 118590 and I'd go with the Curt # C45017, because it's manufactured domestically instead of overseas. You'll also need a # PC2 hitch...
    view full answer...

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Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Michael H
Expert Research:
Michael H
Employee Lindsey S
Written by:
Lindsey S
Employee Laura H
Updated by:
Laura H
Employee Wilson B
Updated by:
Wilson B
Employee Alexander C
Updated by:
Alexander C
Employee Isabelle B
Updated by:
Isabelle B
Employee Cole B
Installed by:
Cole B

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