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  1. Custom Fit Vehicle Wiring
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  3. Trailer Hitch Wiring
  4. Custom Fit
  5. 4 Flat
  6. Powered Converter
T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
Tekonsha

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

Part Number: 118790
In Stock
$40.77
Retail:$60.06
You Save: 32%
Custom Fit Vehicle Wiring

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T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector Custom Fit 118790
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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. 1-800-940-8924 to order Tekonsha custom fit vehicle wiring part number 118790 or order online at etrailer.com. Free expert support on all Tekonsha products. Great prices 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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Tekonsha Custom Fit Vehicle Wiring - 118790

  • Trailer Hitch Wiring
  • Custom Fit
  • 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.


Features:

  • 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
  • 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


Specs:

  • Maximum amperage:
    • Stop/turn lights: 5 amps per circuit
    • Tail lights: 7.5 amps per circuit
  • 1-Year limited warranty


Installation

This custom-fit T-One connector plugs into your vehicle's wiring harness, which is located inside your trunk, behind the rear interior trim panel on the driver's side of the rear cargo area. You will need to remove access panels, threshold, trunk floor panels, and trays to access the harness. Once you've plugged in the T-connector, pull back the interior trim panel on the driver's side and locate the ground stud. Loosen the bolt, place the screw eyelet on the stud and re-tighten the bolt.


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.



118790 Tow Ready T-1 T-Connector - 4 Wire - Modu-Lite

Installation Details 118790 Installation instructions

This Product Fits The Following Vehicles



California residents: click here


Customer Satisfaction Score:


Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - 118790

Average Customer Rating:  4.9 out of 5 stars   (112 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.

by:

Easy install. Bought this with the Curt Class III hitch. All components match up and install without a struggle. The Tekonskha Custom Fit harness incorporates turn signals, running lights and brake lights.



by:

The product had all the necessary instructions and parts to make the installation very easy. The harness is very simple to use.



by:

All parts arrived in a speedy manner and in great condition! Big thank you to Brent J for all his hard work and extremely fantastic customer service!! Easy to follow install videos for tow hitch and electrical components. Thanks etrailer Team!!



by:

Solid product. Very clear and accurate installation instructions customized exactly to my specific vehicle year and model.



by:
2019 Subaru Ascent

Fit perfect and the DIY video was spot on

Sean

1/10/2024

Still working without issue



by:
2022 Subaru Ascent

Very easy installation, I followed the video online and got it down very quickly.
Great instructions and installation!

Steven

4/21/2023

It’s been a year already?!, time flies and it works great! Doing some remodeling and had to hook up my old harbor freight trailer to haul the deconstructed 10x20 shed to the dump. Wiring was fine!



by:

Best experience I have ever had buying car parts! Sales person (Melissa) was competent Delivery was 2 days (a day ahead of schedule), instructional videos were concise and clear. Trailer hitch and harness were well made and fit perfectly. Installed cost was less that a fourth of OEM quote.



by:
Subaru

This worked well on my 2020 Subaru Ascent. The only reason for 4 stars instead of 5 is due to there not being a clamp or something to hold the final cable in place. It isn’t a big deal, you can tuck it into the bumper and that seems to be fine but would have liked a better setup there. Overall great harness and pretty easy to install.

Beau

2/23/2023

Been great over the past year. Used it on a few different trailers and uhauls. No issue and the harness hasn’t fallen out so no issue there



by:
2020 Subaru Ascent

This harness was super easy to install and run down through the grommet to the hitch for easy access. I ended up adding some plastic wire loom for protection under the car but was highly satisfied with all of the components in the kit. Watch the video clip for some tips and order with confidence!



by:
Subaru

I purchased this for my 2019 Subaru Ascent along with a Drawtite hitch 76253 and a brake controller with a dash mounted control knob so that the actual controller is hidden near the steering wheel shaft hidden under the dash. All three items were installed and we enjoyed a great summer of RV trailer camping in the summer of 2019.

John

5/1/2021

I had an RV service professional install it because I am too claustrophobic under my Ascent and I am very happy that it is hidden behind with only the control button visible and it works great!



by:
2021 Subaru Ascent

Received my order in a timely manner. Very pleased with the hitch and wiring. Installation went smooth due in part to excellent videos.



by:

Arrived quickly with my hitch and, after watching the video (A must!), it installed very easily and quickly with no surprises! This can easily be installed with just the tool needed for attaching the ground wire.

Travis P.

3/30/2020

Great! Required some voltmeter testing to match the right wire to the right harness wire though.



by:

Great product. Works perfect and was very easy to install and disappears when not in use.



by:

Very easy to install. The only difficulty is actually getting to the place where the harness is to be placed. Instructions are easy to follow and, with a little care, the system can be installed with no issues.

Bruce

8/24/2021

Still working very well.



by:
2019 Subaru Ascent

Super simple to install, and the video was very specific to my vehicle.



by:

Etrailer had what I needed a good price and came a day earlier



by:

I ordered this item along with the trailer hitch and a bracket. The item was packaged great and arrived in timely fashion. The company was fantastic to work with and service was outstanding.

Finally, the online tutorials on the etrailer website made putting these items in place easy.

I am 150% satisfied with everything this company has done!



by:
2020 Subaru Ascent

I have been using etrailer.com for several years on multiple vehicle hitch and wiring projects and I have always been very pleased with the product and my experience. This time was no different. I needed to install a hitch and wiring harness for a 2020 Subaru Ascent. The parts that were matched with my vehicle online fit perfectly. The instructional videos that accompany every part are outstanding. Each step is clearly explained and easy to follow. Once again, etrailer.com delivered exceptional service, prices, parts, delivery, and everything else I needed to complete my hitch and wiring project in just a few hours. I highly recommend etrailer.com and I will continue to be a customer for several decades to come.



by:
2020 Subaru Ascent

Product was as described. It fit perfectly on my 2020 Subaru Ascent an was very simple to install the hitch and harness. Took about about 75 minutes. Products were high quality. Also saved about $700.00 if a Subaru dealer installed. When not in use it is totally concealed by the center removal bumper face plate.

Highly recommend this product.



by:

Works perfectly. Easy install.

Benjamin

6/16/2023

No problems, no regrets!



by:

Super easy to install. The install video walks you through each step, and there were no surprises when I installed it on my vehicle. Really like the black box that protects the vehicles wiring in case I rent a trailer with a short in it.



by:

Very helpful staff. I had trouble with the shipping companies which sent the order to the wrong location, not etrailer's fault. The team at etrailer resolved the shipping issue. I am satisfied with the merchandize I received, etrailer stands behind their products and were helpful in selecting the right combination of components. Great company, great phone service!



by:

I’m very pleased with the wiring harness and tow bar. Both were very easy to install. It only took about 3 hours and no cutting or drilling was needed. I’d buy again



by:

The install was straight forward. If I hadn't been also installing a trailer brake controller the entire install would have taken all of 15-20 minutes. Very simple!



by:

I was impressed with the installation service, the finished appearance and the price.

Paulette W.

1/3/2022

Its great!


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Show More Reviews

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

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    For your 2021 Subaru Ascent there are four trailer hitch receivers that will be all be hidden behind the center bumper cover, the EcoHitch # 306-X7381, the Curt # C25VR, the Draw-Tite # 76253, and the etrailer # e55ZR. These hitches are all pretty similar as they all share the same 750lb tongue weight rating and 5,000lb trailer weight rating, and will all install with the crosstube hidden so only the receiver itself will be visible. Since all of these hitches share the same design they...
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  • Recommended Trailer Hitch Receiver for 2022 Subaru Ascent Premium
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    I'll start with the EcoHitch Invisi Trailer Hitch Receiver # 306-X7381. The price on any EcoHitch comes from the material used in the construction of the hitch. It uses a special alloy made of recycled materials and combines aluminum, steel, and stainless steel. You are right about the OEM hitch too, a lot of times they come with a wiring harness. On some vehicles if you get it with the OEM hitch the bumper may also be different to allow for an OEM look. For your 2022 Subaru Ascent that...
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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Joshua S
Video by:
Joshua S
Employee Dustin K
Video by:
Dustin K
Employee Jacob T
Video Edited:
Jacob T
Employee Chris R
Video Edited:
Chris R
Employee Wilson B
Updated by:
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Employee Hannah L
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Employee Isabelle B
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Employee Alexander C
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Employee David F
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