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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 # 118402
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Custom Fit Vehicle Wiring

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Tekonsha Trailer Hitch Wiring - 118402
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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 118402 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.
  • All Info
  • Reviews (16)
  • Q & A (0)
  • Photos
  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118402

  • 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 beneath your vehicle, near the trailer hitch. A mounting bracket (sold separately) is recommended to keep the connector secure.

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.

118402 Tow Ready T-1 T-Connector - 4 Wire - Modu-Lite

Installation Details 118402 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 - 118402

Average Customer Rating:  4.8 out of 5 stars   (16 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.

- 118402
Dodge Magnum

This was a 2nd purchase of a trailer wiring for my dodge magnum and had zero issues with. Just sold the car recently so cannot tell you anything further on this.

- 118402

This wiring harness went in without a hitch (no pun intended). Instea of running the power line to the front of the vehicle and attching it to the battery jumping location I drilled a small hole behind the light and was able to run the wire into the trunk and hook directly to the battery. Saved a bunch of time and hassle.

I did the same thing when I installed it in July 2012 but now May 2013 I only get a left turn signal.I remounted the ground and now looking to wiggle the parts to see it if that helps but a visual inspection showed nothing.
-- comment by: Tom L - 05/23/2013

Tom, sorry to hear the harness if giving you trouble. I have added a link on diagnosing trailer harness problems, and you can always give us a call at 1-800-298-8924 and one of our Customer Service team will walk you through diagnosing wiring woes.

-- Etrailer Expert Patrick B - 5/24/2013

Thanks Patrick B., I wiggled all the wires and nothing.Cant I just open up the board box and directly link the wires?Is this still under warranty?I did forget to unplug the connection when I put it in the water. Would this do it?I will call Tuesday, May 28. Thank you for a great site.
-- comment by: Tom L - 05/27/2013

No way to open up the box, it is molded to the board, so opening the box will destroy it. The risk with submerging a trailer in the ramps with the harness connected is two fold, the hot bulbs contacting cold water can pop and if the water could induce a short but that should blow the fuse. Give us a call on Tuesday and we can help you out.

-- Etrailer Expert Patrick B - 5/28/2013

I bought another harness. If you want the old one back to see what happened let me know. I find it hard to believe putting the trailer in the water with the buss hooked up would short out the harness but I guess it did. I will never do that again. It is a cost I would rather now pay each season.
-- comment by: Tom L - 06/28/2013

It is always best to un-plug before backing the boat trailer into the water. Most of the time it is not a problem, but taking the extra reduces the risk to the harness.

-- Etrailer Expert Patrick B - 7/2/2013

- 118402
2006 Dodge Magnum

I placed my order on a Friday evening around 9pm. I was not expecting to get any shipping notice until after the weekend. I received an email about 2 hours later saying my hitch was about to ship! No other company I've ever shopped online with was that quick. I choose the 3-5 day shipping and got it Tuesday afternoon. Both the hitch and wiring harness purchased are top quality. Only negative I have is that I have to download and print out the mounting instructions...

- 118402
2006 Dodge Magnum

Last time i went to trailer my boat for my final fishing trip the harness failed. Had weak signal to the trailer / tester i had hooked up. Had a blown fuse and replaced but the issue remained. I have not tried to trouble shoot beyond my angry day in the pouring rain that day.

- 118402

Not sure why they recommend running the power wire all the way to the front of the vehicle (to the remote jumper terminal) when the battery is located in the right rear corner of the car. Otherwise, the product itself is easily installed and works as intended.

- 118402
2006 Dodge Magnum

Perfect. Looks like they made a change in the harness which is where the last one failed after years of use. Great product.

- 118402
2005 Dodge Magnum

Shipping, awesome! Part was right and worked great!! When I need trailer parts or anything to do with trailer needs, I'm buying from this website. Prices are right on! And shipping is fast! Thank you! Jessie

- 118402
2007 Dodge Magnum

Installed this to replace one that smoked. Has been working great all year.

- 118402
2006 Dodge Magnum

Items arrived on time as advertised. Instructions were great and had no problems with installation. Great product!

- 118402

Product works great. Very fast delivery.

- 118402
2008 Dodge Magnum

Easy to install and work.

- 118402

Easiest kit ever. 100% accurate descrip tion!!

- 118402
2005 Dodge Magnum

Fits well. Installation video was very helpful. Shipping was very fast. Good price.

- 118402
2001 Dodge Magnum

very happy with the service...

- 118402

- 118402
2005 Dodge Magnum

great prices. accurate and speedy delivery. will use them again


Ask the Experts about this Tekonsha Custom Fit Vehicle Wiring

  • Trailer Lights Do Not Turn On but Wiring Harness on 2006 Dodge Magnum Shows Power
    Sounds like the wiring on the 2006 Dodge Magnum is working since you have tested it. But, make sure that the main ground for the converter is attached to a bare metal surface. Moving the ground might help as well. Sometimes, when there is very little load on a system with a bad ground, like using a tester, the problem will not show up until there is more power draw. I also recommend trying out the trailer on another vehicle if possible. After checking that, that leaves the trailer. Most...
    view full answer...
  • Installation of the Positive Connection from Wiring Harness To Battery on My 2005 Dodge Magnum
    If you installed the power line from the converter to the battery you should have power to the trailer lights. The terminal under the hood is fused so it would provide an extra layer of protection, but is not necessary as long as the inline fuse is used. If all the other wiring is connected properly to the connection points behind the taillights. You may have a bad ground somewhere or the fuse may be bad if you did not remove it before installing the power wire. If you did not install...
    view full answer...
  • Troubleshooting T-One Vehicle Wiring Harness # 118402 on 2007 Dodge Magnum
    It sounds to me like you may have a ground problem. There are several places to look for a poor ground connection. I recommend starting with the trailer connector on the vehicle. You will want to check to make sure it is securely grounded to a clean metal surface on the vehicle frame or chassis. Next, I would take a look at the connector on the trailer. Check to make sure that it is free of dirt and corrosion and that the ground wire is securely grounded to a clean metal surface on the...
    view full answer...
  • Why Does Power Wire of the Trailer Wiring Harness for 2005 Dodge Magnum Need to be Run to Battery
    The reason you want to run the power wire all the way up to battery is so that you bypass all of the delicate wiring of your vehicle. The power wire is required on trailer wiring harnesses for some vehicles because the electrical system on those vehicles cannot handle the amperage draw associated with trailer lights. Powering the converter box with a power source that doesn't come from the battery would defeat the purpose. I attached an FAQ article on routing the power wire for you to...
    view full answer...
  • Why Would Going with Larger Fuse in Tariler Wiring Cause it to Burn Up
    The higher fuse you installed is the reason the harness burned up. The rating of the fuse is designed to kill the connection if a short is present that would cause damage. By going with a higher rated fuse you essentially allowed the connection to stay in tact beyond the amperage rating of the wiring so it ended up burning itself. The fact that you were blowing the properly rated fuse indicates that you had a short or were overdrawing the harness which should have been what was addressed...
    view full answer...
  • Troubleshooting Trailer Wiring Harness on 2007 Dodge Magnum with Always-On Left Brake Light
    You did indeed purchase a trailer hitch from etrailer back in January of this year but I did not find a record of a wiring harness purchase. In any case the problem you describe is most likely caused by either a damaged wiring harness or by a bad connector at the vehicle or trailer. I suggest you first check that the ground wire is firmly attached to a clean bare metal surface. A bad ground can cause all sorts of weird issues. If this does not help next disconnect the harness connectors...
    view full answer...
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  • Troubleshooting Trailer Wiring that has Blown Up Two Tail Light Converters
    Although taillight converters, just like any other electronic device have a set lifespan, losing two of them in rapid succession tells us that something is going on. The two most likely causes are a short circuit in the trailer wiring and overloading the converter. First, check the wiring on your trailer. Beginning at the trailer connector and working your way back to each lamp, closely examine the wiring. Wire insulation can become brittle over time, look for any cracked or worn wire...
    view full answer...
  • Hitch Recommendation for a 2005 Dodge Magnum
    The Curt Trailer Hitch Receiver # 13465 that you referenced is the confirmed to fit your 2005 Dodge Magnum. For trailer wiring you would want the part # 118402. For ball mounts I recommend the etrailer Ball Mount Kit # 989900. It comes with 2 ball mounts, 2 balls, a hitch pin with clip, and a carrying bag.
    view full answer...
  • Does Wiring Harness for 2006 Dodge Magnum Install on Specific Side of Vehicle
    The wiring harnesses for your 2006 Dodge Magnum, the Hopkins Plug-In Simple Vehicle Wiring Harness # HM11142195 and T-One Vehicle Wiring Harness # 118402 won't have a specific side of your vehicle to install on. They utilize the taillight assemblies to install. I have added links to the instructions as well as an install I recommend checking out on a 2006 Dodge Magnum of the T-One Vehicle Wiring Harness # 118402. This will give you a good idea of how the install will go. Additionally...
    view full answer...
  • Parts Needed to Install Brake Controller in 2005 Dodge Magnum
    You will need to start with a 4-way (if you do not have one). For that you would want the # 118402. From there you would need to convert the 4-way to a 7-way so that you can install the brake controller. For that you will want the Brake Controller Install Kit and 7-Way Adapter part # ETBC7. I attached installation instructions and an install video for this product as well. For a brake controller I would recommend the Prodigy P2 Brake Controller part # 90885. This is our best selling brake...
    view full answer...
  • Recommended Curt Receiver Hitch for 2005 Dodge Magnum RT
    Curt offers two different receiver hitches for your 2005 Magnum, the Class II you mentioned, part # 12240 or a Class III, part # 13465. Although both receivers would work great on your vehicle, I always recommend choosing a Class III with a 2 inch receiver opening over the Class II with the 1-1/4 inch opening whenever the option is available. The more common Class III 2 inch receiver will provide a better selection of hitch mounted accessories like bike racks or cargo carriers. If you...
    view full answer...

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