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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 # 118646
Our Price: $87.50
You Save: 38%
Custom Fit Vehicle Wiring

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Tekonsha Trailer Hitch Wiring - 118646
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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 118646 or order online at 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 - 118646

  • 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 rear cargo area
    • Plug in T-connector
    • Run hot lead to car battery
  • Includes ModuLite power converter to ensure that your vehicle's wiring matches that of your trailer
    • Powered module connects 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: 4.2 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 in your rear cargo area on both the driver's side and the passenger's side. You will need to remove the threshold, floor panels, cargo trays, and interior trim panels 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 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 your vehicle runs on a multiplex wiring system, the wiring needs to be converted to be 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.

118646 Tow Ready T-1 T-Connector - 4 Wire - Modu-Lite

Installation Details 118646 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 - 118646

Average Customer Rating:  4.9 out of 5 stars   (93 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.

2013 Volkswagen Passat

The Tekonsha was an easy install on a 2013 Passat. The hardest part of the install is removing interior trim to hide power wire. Works as designed.


Works as advertised, snaps right into existing wiring. Removing interior panels of vehicle to expose existing wiring maybe the only challenge depending on your vehicle. VW e-Golf installation was pretty straight forward.


great product , great directions! And fits perfect!!


The 118646 kit worked great! I called in because I was confused regarding the application listed on the box (Golf) and my car which is a Passat. The young lady on the phone was extremely helpful. When I got the confirmation, there were two videos that showed me EXACTLY how to install it. The video was clear and professional. Although I didn't enjoy crawling under the car, I was able to successfully install the kit and it even works. Thanks for your extra help.



Works great! No issues.

2015 Volkswagen Passat

I installed the harness on my 2015 Passat TDI. The instructions were very clear to understand and the video was very helpful.The harness is working as designed.


This is a direct plug and play. The service from Etrailer is also fantastic

2017 Volkswagen Golf

I installed this harness on my 2017 Golf GTI. All tee connections fit the OEM sockets perfectly. The location I chose to mount the module required me to extend the left socket wiring (yellow wire). No big deal. There is a rubber body plug on the floorpan on the drivers side rear corner that can be used to exit the 12 volt battery wire from the rear compartment. I ran the battery wire externally underneath the chassis attaching to the brake lines using zip ties. I removed the underbody splash shield on the drivers side to access the brake lines and then reinstalled afterwards. Removing and installing the rear trim panels to gain access to run the module wires from left to right took the most time. I am very detailed oriented and I spent what time was necessary to end up with a superb installation.

Gary R.


After one year everything is working perfectly!


Oregon to Colorado in 22 hrs non stop without a single hiccup. Everything worked great


Amazing product customer care was on point I spoke with Chelsea and she was amazing. Got everything figured out and everything here quicker than expected. Highly recommend.


It fits and works fine on my 2016 GTI SE. ETrailer is doing their customers a disservice telling them the Tekonsha wiring harness does not fit the MK7 GTI. I had read that several people had used it without issue, and went as far as contacting Tekonsha and speaking to a tech person there. They agreed that circuitry and electronics-wise, there is no difference between this and the other that would require splicing, and it comes down to whether the plugs are correct and are reading the signals on the correct wires. The plugs are an exact fit and it maps the yellow and green signal wires to the correct wires on the car harness, the same ones identified on the recommended splice harness. It would be helpful if ETrailer and Tekonsha could work together to get the application specs for 118646 updated to include the GTI so it could save customers like me time researching this, and the anxiety about buying and using something that supposedly doesn't fit.


Hitch and wiring are working flawlessly. Best decision I made adding a hitch to my car to carry items that would not fit inside.

Cliff B.


Everything is still working very well and I am very pleased with my purchase.


Great product. Super happy with it. No issues. Also, when I called you guys for help, you were very helpful and friendly. Can’t recommend you enough!


Made the mechanic watch the video on installation before we got started. Hitch and wiring went on effortless..

Denny F.


Works great,have a small 5x8 trailer for getting our racing kart to the track.


I had purchased the stealth hitch, coil over air bags and wiring harness, all products were top shelf top name and top quality, absolutely no regrets. Customer support and service were real professional and very knowledgeable. I’m still using etrailer for more products, now some of my friends are too.

2015 Volkswagen Passat

Original wiring harness had a problem and did not power running lights when installed per instructions. etrailer customer service was great to work with and got a replacement product out to me promptly. All my lights are now working. Installation video clearly show how to install product and is a great time saver.


When i needed to add a trailer hitch to my car for a move, i searched around and this was pretty much the cheapest priced hitch i could find( about a hundred cheaper than uhaul) so i got it and installed myself without taking the bumper off and im very pleased with my purchase. If i ever need to put a hitch on another car i will be coming here first, thanks!!

2015 Volkswagen Golf

Wiring harness and trailer hitch for my VW Golf fit fine, no monkeying around. It took an afternoon to work through the process of installing the parts, but there were no significant snags in getting it done. Reviewing the instructions and available videos before hand were helpful.


Was very simple and easy to install.

2013 Volkswagen Passat

I installed this wiring kit with the help of one other person on my 2013 VW Passat. Connecting everything in the trunk area was extremely simple due to the T-connections. Running the power supply line to the battery took the most time to ensure proper routing, but it was fairly simple. Removing protective plastic shields exposed many lines to zip tie the wire onto and ultimately made the install safe for the long term.

Volkswagen Passat

Wiring was fairly easy to install. Directions were easy, this was better than cutting and splicing into factory harness. The passat has a plastic skid plate that comes off and makes for easy wire runs. overall im happy with the hitch and the wiring


I want to thank my etrailer customer service contact, Ashley E for helping me finish my wiring project.
When I began preparing to install wiring harness when I realized I had ordered the incorrect part number.
I called etrailer Customer service and Ashley promptly reviewed my order and identified the appropriate harness for my vehicle. She generated an order for the correct product and arranged for the return of my incorrect product.

I was surprised and delighted to find that the new product arrived 3 days later.

The correct harness is a custom product that is connected with coupling connector that plugs in between the tail light wires and the light. All I had to do is route the power wire to the battery. It works perfectly!
Thanks Ashley and etrailer for a great experience.
Jamie S


I had no problems installing the trailer hitch it was like a breath of fresh air.wiring it up was very easy and I must say the connectors was an easy way to connect to the existing wiring.

2014 Volkswagen Passat



Wiring a car to tow is nothing like the old days. I ordered the custom harness, arrived very soon, installed per the instructions and video, now my trailer is all nice and legal. I don’t have a truck, economy and long commute prohibit that, when I need one, I hook the trailer instead, E-Trailer has always had my towing solutions.

2017 Volkswagen Golf

Installed in my 2017 Golf R and works great. Install of the hot lead to the battery was the hardest part. I ran the lead under the door trim panels and under the carpet in the footwell. Found a blanked grommet in the firewall to run through to the battery. Sano install once done.

Show More Reviews

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

  • Trailer Wiring Harness Recommendation for a 2016 Volkswagen Golf
    If it were my 2016 Volkswagen Golf I would install the Tekonsha harness # 118646. I would choose the Tekonsha harness because we have heard of less issues with these wiring harnesses. They install the same way and perform the same functions with little difference other than the design of the circuit boards and amperage ratings like you pointed out. I have included a link to the instructions for you.
    view full answer...
  • Trailer Wiring Recommendation for 2018 Volkswagen Golf
    For your 2018 Volkswagen Golf the best trailer wiring option we have is the T-One kit part # 118646 for the non-R models. The T-One brand of trailer wiring harnesses is our most reliable option we offer so we recommend it the highest.
    view full answer...
  • Does Trailer Wiring Harness for 2016 Volkswagen Golf Draw Constant Power
    Unless there is something plugged into the 4-Way trailer connector that is drawing power trailer wiring harness # 118646 for your 2016 Volkswagen Golf will not be drawing any power from the vehicle battery. Think of it like a 12 volt power outlet (cigarette lighter) in a vehicle or a wall outlet. It has power to it all the time (some of them do anyway) but they don't draw any power until something is plugged in and turned on. So in terms of current (amps) there isn't a draw though it will...
    view full answer...
  • Trailer Wiring Troubleshooting on 2015 Golf SportWagen
    Use your circuit tester on the Right Turn input from the vehicle wiring harness before it reached the taillight converter. Activate the right turn signal, you should see power on the green wire. Then, check the green wire on the output side of the converter, that leads to the 4 pole trailer connector. If you have power entering the converter, but not leaving it, the converter is bad. If there's no power entering the converter, then check the T connection where the harness plugs in to the...
    view full answer...
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  • Custom Fit Wiring Harness Kit 118730 for 2017 Volkswagen Golf SportWagen
    The custom-fit plastic connectors on wiring harnesses like # 118646 (which fits the 2013 Volkswagen Passat) and # 118730 (which fits the 2017 Volkswagen Golf SportWagen) are not offered as separate parts, sorry to say. Since your existing wiring harness kit is a hardwired type I understand why you'd prefer not to have to cut into the new vehicle's wiring, but for that you'll need kit # 118730 for the SportWagen.
    view full answer...
  • Trailer Wiring Harness for a 2016 Volkswagen Golf R
    There are no specific wiring harnesses for the R model of the 2016 Volkswagen Golf. Your best option is to use the ZCI harness # 119250KIT which is a universal harness but does not require splicing into the vehicle wiring.
    view full answer...
  • Advantage to Curt Hitch with Euro Ball Mount for 2016 Volkswagen Golf
    I like the Euro ball mounts like what come with the part # C114121 as they are just a simpler design that doesn't require you to install a ball onto the ball mount. It's permanently fixed there so it is always ready to go. Also it's a bit less bulky so it stores a bit easier. This is a fit for your 2016 Volkswagen Golf so if you need a hitch and a ball mount that has a 1-7/8 inch ball this would be the part number you would need. For trailer wiring you then would want the # 118646 which...
    view full answer...
  • Trailer Wiring Harness for 2015 Volkswagen Golf GTI
    For your 2015 VW Golf GTI, you'd want to use the ZCI Circuit Protected Vehicle Wiring Harness # 119250KIT. The # 118646 harness you asked about is compatible with the 2015 VW Golf with the exception of GTI and Sportwagen models.
    view full answer...
  • Trailer Wiring Harness Recommendation for the 2016 Volkswagen Golf SportWagen
    For your 2016 Volkswagen Golf SportWagen I recommend the Tow Ready ZCI harness # 119250KIT. This harness is unique in that it does not require splicing into the vehicle wiring. Instead, its connectors clamp around the vehicle wires and sense the electricity passing through them. It's kind of awesome!
    view full answer...
  • Trailer Wiring Harness Recommendation for a 2015 Volkswagen GTI
    For trailer wiring for your 2015 Volkswagen GTI all we have at this time is a universal hardwire kit like the part # 119250KIT. The # 118646 would not be the correct wiring kit for your vehicle.
    view full answer...
  • 2015 Volkswagen Golf Sportwagen TDI SE Trailer Wiring Recommendation
    For your 2015 Volkswagen Golf Sportwagen the only trailer wiring kit we offer that has been confirmed as a fit is the part # 119250KIT. This will require that you run a wire up to the batter of the vehicle as well. I attached an install video that shows how it would install in a similar vehicle.
    view full answer...
  • Trailer Lights Not Lighting or Lighting when Not Supposed to with 2015 VW Golf SportWagen
    To determine if the problem is on the vehicle side or the trailer side you can do some testing with a circuit tester such as # PTW2993 or a meter if you have one. Disconnect the trailer and use the circuit tester to test the 4-Way connector on your 2015 Volkswagen Golf SportWagen while someone sits in the car and goes through the light functions. The pin next to ground is running lights, the next pin is left turn signal and brake lights, and the last pin is right turn signal and brake...
    view full answer...
  • Recommended Wiring Harness with 4-Way Flat for a 2012 Volkswagen Passat
    The Upgraded Modulite Vehicle Wiring Harness Kit # 119147KIT that you referenced is a universal kit so technically it will fit all vehicles. However, since we have the Tekonsha T-One # 118646 at a similar price that is a custom fit for your 2012 Volkswagen Passat there is no need to use a universal item. The universal option requires hardwiring everything while the T-One clips in behind your tail lights and then a 12V power lead is run to the battery. This is a much easier install. I...
    view full answer...
  • 2012 Audi A6 Trunk Liner Removal for Trailer Wiring Install
    From the research I did on your 2012 Audi A6 it looks like to remove the trunk liner you will need to remove the warning triangle that is in your trunk and then remove the screw that holds the emergency release handle in place. There are 10 panel clips that hold the trim panel in place. You can use a panel removal or gently pull on the panel to get it to remove.
    view full answer...
  • Troubleshooting Intermittent Trailer Light Functioning on a 2001 Kia Sportage
    Bizarre tail light behavior on a trailer is almost always due to a bad ground. I would recommend you check the ground you used for the tail light harness and make sure it is connected to a clean metal surface. You might even try a totally different location for the ground. You could even try running the wire up to the negative side of the battery just to rule out the possibility. If that does not fix it I would try uninstalling the trailer wiring harness and reinstalling it. There may...
    view full answer...
  • Trailer Hitch Receiver Fit For 2013 Volkswagen Passat w/ 2.0L Diesel Engine
    There is a trailer hitch that fits your 2013 Volkswagen Passat with the 2.0L diesel engine, from Draw-Tite: - Draw-Tite Sportframe Trailer Hitch Receiver # 24880 The # 24880 is a 1-1/4 inch hitch and is nice because the crosstube is concealed behind the bumper so only the receiver shows, which means your Passat will maintain its factory appearance. Additionally, if you are going to use this hitch for towing and also need a 4-way trailer connector, the correct fit for your '13 VW Passat...
    view full answer...
  • Troubleshooting Trailer Wiring Kit On a 2011 Volkswagen Touareg that Blew Fuse and Stopped Working
    What you will want to do is test the wires going into the box of the converter box for voltage with a circuit tester like the # PTW2993 to see if there is voltage going into the box when the taillight functions of your vehicle are applied, and then test the output side of the box to see if the current is making it through the converter. If not then the problem is that the converter box has shorted itself out and would need to be replaced. Before you replace it you will want to inspect...
    view full answer...
  • Magnetic Tow Lights Recommendation For 2015 Volkswagen TDI Beetle Being Flat-Towed
    For the easiest and most convenient lights for towing your 2015 VW Bug, I recommend using magnetic lights, the Peterson # PE26UR.
    view full answer...
  • Trailer Hitch Recommendation for a 2015 Volkswagen Passat Sport
    For a trailer hitch confirmed to fit your 2015 Volkswagen Passat you would want the Draw-Tite part # 24880. I attached an install video for this hitch for you to check out as well. If you were planning on towing a small trailer, you might lean toward the Curt hitch, as the draw bar and pin and clip are included. You might also need the following to complete your towing system. Trailer wiring harness # 118646 2 inch trailer ball # 19258 1-7/8 inch trailer ball # 19256
    view full answer...
  • 4-Pole Trailer Wiring Harnesses for 2015 Volkswagen Golf and 2015 Volkswagen GTI
    The 2015 Volkswagen Golf and the 2015 GTI do call for different wiring harnesses. Tow-Ready 4-pole # 118646 is a custom-fit powered harness that plugs in at the tail lights of the 2015 Volkswagen Golf using vehicle-specific connectors. For the 2015 GTI only universal-fit harnesses are available, Tow-Ready # 119250KIT and Curt # C59236, both of which are hardwire installs. These do not have the connectors to match the car. Both of these will require splicing of wires and you'll need to...
    view full answer...
  • Recommended Trailer Hitch Receiver For 2014 VW Passat 1.8L Turbro Wolfsburg Edition
    For your 2014 Volkswagen Passat 1.8L Turbo Wolfsburg, I recommend the Draw-Tite Sportframe Trailer Hitch Receiver - Custom Fit - Class I - 1-1/4" # 24880. This is a bolt on installation hitch with a sturdy square tube design. The Draw-Tite Class I hitches do not require a stabilization strap like the Curt hitches do for accesories. If you will be doing light towing with this hitch or want a lighted accessory, I recommend the Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat Trailer...
    view full answer...
  • How To Find Correct Trailer Wiring Harness for 2019 VW Golf
    There are multiple trailer wiring harness options for a 2019 Volkswagen Golf because there are so many different trim levels; GTI, Alltrack, R, Sportwagen, etc. In order for us to confirm fit we will need to know which exact one you have. The Tekonsha T-One part # 118646 fits most models but there are ones it does not fit such as the Sportwagen and Alltrack and in which case you would use the ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation...
    view full answer...
  • Trailer Wiring Harness Options for a 2014 Volkswagen Golf
    The ZCI harness # 119250KIT is one of the wiring harnesses that you can use on the 2014 Volkswagen Golf. It is the only one that does not require splicing into the wiring on the vehicle. The other option, # C59236, requires splicing into the vehicle wiring.
    view full answer...
  • What is the Correct Tekonsha Wiring Harness for a 2015 Volkswagen Golf SportWagen
    I took a look at the answer pages that you were referring to and you are correct that the T-One # 118646 was recommended. It is no longer a fit for the 2015 Volkswagen Golf SportWagen and those questions were completed before a statement came from Tekonsha stating that it won't fit the 2015. I have sent an update for those answer pages to change, thank you for helping us out with that. The T-One # 118730 that you mentioned is a fit for all models of the 2016 Volkswagen SportWagen and the...
    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 Jameson C
Expert Research:
Jameson C
Employee Adam R
Expert Research:
Adam R
Employee Jeffrey L
Expert Research:
Jeffrey L
Employee Lindsey S
Edited by:
Lindsey S
Employee Jacob T
Video Edited:
Jacob T
Employee Dustin K
Video Edited:
Dustin K
Employee Chris R
Video Edited:
Chris R
Employee Kathleen M
Video by:
Kathleen M
Employee Laura H
Updated by:
Laura H
Employee Wilson B
Updated by:
Wilson B
Employee Isabelle B
Updated by:
Isabelle B
Employee Cole B
Installed by:
Cole B
Employee Alexander C
Written by:
Alexander C
Employee Shane H
Test Fit:
Shane H

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