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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 # 118502
Our Price: $60.76
You Save: 43%
Custom Fit Vehicle Wiring

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Shipping Weight: 1.66 lbs
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Tekonsha Powered Converter Custom Fit Vehicle Wiring - 118502
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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. 1-800-496-5010 to order Tekonsha custom fit vehicle wiring part number 118502 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.
  • All Info
  • Reviews (11)
  • Q & A (0)
  • Photos
  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118502

  • 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 behind tail lights
    • 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 behind the driver's-side and passenger's-side tail lights. You will have to remove the tail light assemblies to access this harness.

T-One Connection Location Points Behind Tail Lights

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 trunk or 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.

118502 Tow Ready T-1 T-Connector - 4 Wire - Modu-Lite

Installation Details 118502 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 - 118502

Average Customer Rating:  5.0 out of 5 stars   (11 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.

2010 Mercury Milan

Great price for a great product. I’ve been doing lots of trailering delivering various things to the house I just bought, and the trailer light package has never let me down. Insulation on the wiring is high quality. The northeast winters don’t bother the computer, and the salt doesn’t bother the underbody wires.

2008 Mercury Milan

Price of products were very good and shipping was quick and right on time as indicated in tracking. If I ever need any other products I would being using this site again. John Caul


Solid construction. Fit perfectly. Works great. Very happy with etrailer customer service and support.

2007 Mercury Milan

I ordered in the morning and got instant response that my order was in stock. About 2 min. later a email that my order was ready to be shipped. Then 1/2 hour later a email that my order has been shipped. That in my mind can not be beat. I tried to order from a different nationally known place and it had a lead time of 6-8 weeks. I received my order 5 days after I ordered, and that was over the weekend. That was not express delivery either. Fit perfectly and easy to follow instructions. Will use again and tell my friends. THANKS Steve


Very Nice was, not difficult and was nice not having to cut and splice any wires


Great product. The kit simplified the whole process. I would definitely buy from you guys again. Thank you.


very easy to install



Real easy to put together. I was really surprised that they had a video specific to my car.


Exactly what I ordered. Packaged well and delivered quickly!


Awesome kit, everything I need for my hook up..


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

  • How Does the Trailer Wiring Harness # 118502 Install on a 2010 Mercury Milan Premier
    Installation of the trailer wiring harness # 118502 is fairly straight forward. The main connections from the harness connect in line with the tail light wiring on the vehicle. The converter will be grounded to a bare metal surface or existing ground location. The only real time-consuming part is routing the power wire to the vehicle battery. If your battery happens to be in the trunk or even under the backseat, this is not very difficult. Most cars and trucks have the battery under the...
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  • Troubleshooting Brake Lights that are Staying On
    I can help you troubleshoot this wiring connection issue. First thing I would do would be to use a circuit tester like # PTW2993 and test the 4-pole at the end of the vehicle to make sure all the functions are properly working. If they aren't, then I would move on to the wiring before the converter box. If this wiring is all running correctly, you may have a bad converter box on your harness. If all the poles are functioning normal, then you may consider checking the wiring on your...
    view full answer...
  • Can a 2009 Lincoln MKZ Pull a Pop-Up Camper
    In order to tow a trailer with a 2009 Lincoln MKZ you'll need a trailer hitch, trailer wiring harness, and ball mount/hitch ball. I will attach a list below with each of these options. In regards to capacity and compatibility, you'll have to refer to your copy of the owner's manual for this which should be located in the glove box. We cannot recommend deviating from the manufactures instructions. Draw-Tite Sportframe Trailer Hitch Receiver part # 24775 T-One Vehicle Wiring Harness with...
    view full answer...
  • Curt Trailer Hitch # 11329 Vs. Hidden Hitch # 60846 for a 2008 Lincoln MKZ
    Both the Hidden Hitch Trailer Hitch # 60846 and the Curt Hitch # 11329 are quality hitches and neither have had any quality or fit issues for us. I attached a page that shows both of these products side by side for you to check out. The only noticeable difference in construction between the two hitches is that the Hidden Hitch has a larger welded on bracket for securing the stinger of the hitch to the cross tube. This might give the Hidden Hitch a slight advantage. I attached installation...
    view full answer...
  • Troubleshooting Trailer Wiring Harness That Instantly Blows Fuse When Connecting to Battery
    The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118502 having a spark as well as blowing a fuse is a sure sign that the ground is not connected properly or the power wire at some point is touching a metal ground. I recommend tracing that power wire to ensure there is no insulation missing where it could be touching metal. You can see with our installation of this wire we used wire loom # 7509-10 in some areas to assist with areas that have sharp edges. If you need...
    view full answer...
  • No-Splice Plug-In 4-Pole Trailer Wiring Harness for 2008 Lincoln MKX
    We do offer both hard-wire and custom plug-in 4-pole wiring harnesses for the 2008 Lincoln MKX. The unit I recommend for your MKX is the custom plug-in harness from Tow Ready, part # 118551. This trailer wiring harness installs by plugging in to your MKX's tail light wiring; just one spliced connection is required, for the 12V power input wire to the converter. (Note that for the MKZ you can instead use harness # 118502 that installs in the same manner.) This connection is made from the...
    view full answer...

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Info for this part was:

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