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

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

Item # TK66VR
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Custom Fit Vehicle Wiring

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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. 1-833-496-1390 to order Tekonsha custom fit vehicle wiring part number TK66VR 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 (1)
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  • Videos (1)
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Tekonsha Custom Fit Vehicle Wiring - TK66VR

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • 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 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 inside your rear cargo area on both the driver's side and passenger's side. You will need to remove the floor covering and some interior paneling 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 and insert the provided fuse.

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

118842 Tekonsha T-1 T-Connector - 4 Wire - Modu-Lite Converter Included

Installation Details TK66VR Installation instructions

This Product Fits The Following Vehicles

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 Review of Tekonsha Custom Fit Vehicle Wiring - Trailer Hitch Wiring - TK66VR

Hello everybody, this is Jeff at Today, we're gonna take a look at the T-One Vehicle Wiring Harness with this 4-way flat trailer connector. Now, this is a custom fit part, it is designed to fit the 2017 and newer Toyota Prius Prime vehicles, and on a custom fit part like this one, I do recommend for you to go to our website, use the fit guide, put in your year and model vehicle, and it'll show you if this'll work for your application. Now, this will provide a 4-way flat trailer connector at the back of your vehicle to power your trailer's signal lights, and this is compatible with 5-pole, 6-pole, and 7-pole adapters that we do sell separately on our website. Now, this does connect very quickly and easily, it includes everything shown here on the table. It comes with a nice set of instructions that will describe how it installs with pictures.

Now basically, what you'll first do is locate your connection points, which will be in the rear cargo area, and then you'll plug in these T-connectors, one for each side, one for the driver's side, and one for the passenger's side, and then you'll ground your white wire here, and then run this power wire up to your vehicle's battery. Now, this does include the ModuLite tail light converter, which is this black box here, and this is to ensure that your vehicle's wiring will match that of your trailer. It is a powered module, connects directly to the battery, and that's to avoid overloading your vehicle's electrical system. Also, this converter is constructed using SMT technology, which is surface mount technology, gives you more consistent, reliable performance, and will maximize the trailer light yield and intensity while producing minimal heat, also ensures superior operation in any rough road conditions. If you noticed on the 4-way, it has the integrated dust cap with it, so when you're not plugged into a trailer, you just put that cap over the terminals, protects it from any damage or from the elements.

Few specs on this wiring harness, the maximum amperage for the stop and turn light circuits is five amps per circuit, for the taillights, it's 7.5 amps per circuit, and the last thing I wanna do is just briefly go through this when you go to install it. But again, what you'll do is go to the rear cargo area of the vehicle, and the instructions will describe where the connection points are, and you'll find the connection points for these two T-connectors, plugged them in, once you get them all plugged in, you see that you have your white wire with your eyelet on it, that's what needs to be connected to a good clean ground, if there's not one nearby, they do give you a ground screw that you can make your own ground, run your 4-way out the back. Now, this ModuLite box does have some weight to it, so you do wanna attach that to a flat surface, so it doesn't bounce around. It does have a tab on it with the hole that you put a screw through, or they do include a piece of double faced tape you can use. Once that's all attached, you'll have one remaining wire, and it'll be this power wire, and this power wire we'll need to run to the front of the vehicle to your vehicle's battery.

Now, they do include this length of extra wire to run up to the vehicle's battery, and what you'll do with connectors, so you'll take a butt connector, attach to one side of this wire, run it up to the vehicle's battery, once you get up to the front, you don't wanna run this directly to the battery, you wanna connect it through this fuse holder. So you'll take your other butt connector, connect it to one side of the fuse holder, just like that. On the other side of the fuse holder, you put on the eyelet connector, and that'll connect to the battery. Once it's all connected, just pop it open, take the included 15 amp fuse, insert it in there, push it all the way down, put your cap on, and now your system's all protected and ready to go. If you noticed, they do give you some extra cable ties to take up any slack in the wiring.

But that should do it for the review on the T-One Vehicle Wiring Harness with the 4-way flat trailer connector..

Customer Reviews

T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector - TK66VR

Average Customer Rating:  4.0 out of 5 stars   (1 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.

2021 Toyota Prius

I installed the receiver on day one, then tackled the wiring on day two. Big mistake on a Prius, install the harness when you already have the bumper cover off! Routing the power line to the 12v battery in the engine compartment without having the car on a lift is a fool's errand. As with the receiver I bought, DIYers should watch the installation video before ordering the product, you might decide to hire the entire installation.


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

  • Is There A 2" Hitch Receiver Available For A 2022 Toyota Prius Prime
    Though we do have the Curt # C11473 and the Draw-Tite # 24966 confirmed to fit your 2022 Toyota Prius Prime, both of these option will have the 1-1/4" receiver. There are currently no options available for a 2" receiver. The EcoHitch # EH53VR is a confirmed fit for a 2019 to 2021 Prius (not Prime), so I cannot recommend it for your vehicle. There may be an option in the near future, but I cannot say exactly when this will be, unfortunately. However, I can recommend the Tekonsha T-One Vehicle...
    view full answer...
  • EcoHitch Trailer Hitch Receiver and 4-Way Wiring Connector For a 2017 Prius Prime
    For your 2017 Prius Prime you will need the EcoHitch Stealth Trailer Hitch Receiver # 306-X7369. The EcoHitch # EH53VR(X7404) will only fit the Prius and not your Prius Prime. I recommend installing the T-One Vehicle Wiring Harness # TK66VR when you install the receiver. This will give you a 4-way flat connector that will allow you to connect to small trailers. It will also allow for the use of Auxiliary Lights # C53201 if you are using a hitch mounted accessory that impairs the view...
    view full answer...
  • Best 2 Inch Trailer Hitch for a 2019 Prius Prime Advanced
    The best hitch for your 2019 Toyota Prius Prime is going to be the EcoHitch Stealth Trailer Hitch Receiver item # 306-X7369. This hitch is custom fit and bolts directly to your Prius with included hardware. This hitch is the only one available that will match your Prius' 300 lbs tongue weight capacity and give you the strength you will need to carry two e-bikes and the bike rack. It is also the only available option we have that will work with the Swagman E-Spec Bike Rack for 2 Electric...
    view full answer...

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Info for this part was:

Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Mike S
Written by:
Mike S

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