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

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

Item # 118719
Our Price: $68.71
You Save: 39%
Custom Fit Vehicle Wiring

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Shipping Weight: 1.75 lbs
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118719 - 4 Flat Tekonsha Trailer Hitch 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. 1-800-940-8924 to order Tekonsha custom fit vehicle wiring part number 118719 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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  • Reviews (37)
  • Q & A (0)
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Tekonsha Custom Fit Vehicle Wiring - 118719

  • Custom Fit
  • Trailer Hitch Wiring
  • 4 Flat
  • 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
    • Connect hot lead to car battery
  • Includes ModuLite power module that 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: 4.2 amps per circuit
    • Tail lights: 7.5 amps per circuit
  • 1-Year limited warranty


This custom-fit T-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. Once you've plugged in the connector, run the hot lead up to your car battery. Connect the included fuse holder, and then connect the fuse holder to the positive terminal on your battery.

T-One Connection Location Points Behind Tail Lights

Once installation is complete, the 4-way 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. 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.

118719 Tekonsha T-1 T-Connector - 4 Wire - Modu-Lite Converter Included

Replaces 118662

Installation Details 118719 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 - 118719

Average Customer Rating:  4.5 out of 5 stars   (37 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.

2015 Ram ProMaster City

12v wire to battery too short



Fine! Power cable to battery was not long enough. I used my own cable to connect the harness to the battery


Works as intended. My second purchase on very satisfied. The etrailer YouTube page is also a great resource.

2019 Ram ProMaster City

Everything went smooth with the wire installation except your power line is too short it should be at least a foot longer to comfortably reach the battery

2015 Ram ProMaster 2500

I too installed this at the same time as the Draw-Tite hitch. I installed mine into a Promaster City Wagon instead of the Cargo Van. The install is a little different. You have to remove the screws holding the speaker panel in and then pull up to remove that part. Then you have four screws under the speaker panel plus a couple more holding the larger panel. You do not have to completely remove the larger panel. Just pry and hold it back about a foot to allow access to the hole described in the video. Everything else is the same EXCEPT where the trailer wiring has to be stored and exit the side metal. There is a little triangular plastic panel near the bottom. This panel just pops out and trailer wiring can be hid behind it.

I do wish the trailer wiring was long enough to be run to the outside and down by the hitch but it is just too short.

I also found the power wire to be about one foot short of ideal. It works, but it is not the ideal length.


This is actually a good wiring kit but I will mention two things. The instructions want you to mount the wiring junction block behind the right tail light. I think it should be pointed out that there isn’t room directly behind the light but there is room in the body cavity directly behind the light enclosure.
When you connect the harness for the first time to each of the tail light plugs take the time to disconnect them again and check to see if any of the pins in the connector got pushed in. If so use needle nose pliars to gently pull on the loose pin until you feel it lock onto place. I mention this because it is easier to double check while you have the tail light removed than it is to take the light out again.

2018 Ram ProMaster City

Without the trailer video this would have been a difficult install. Instead of installing the electronic module with double-stick tape, I found it easier to mount it using the same bolt & nut assembly I used for the grounding wire install—I provided the bolt, nut and star washer. As with all other reviews for this product, the black wire going from the electronic module installed on the rear passenger side of the van to the battery is short by at least two+ feet. Suggestion for the RAM Pro Master City cargo van; the instructions say the harness going to the trailer can be stored in the snap-on panel in the rear. I brought my harness out through a small vent in the corner.

2016 Ram ProMaster City

Everything was included and I installed it in about an hour. Two suggestions I would offer is to provide about one more foot of the power wire and consider wire nuts rather than butt connectors. Without a proper tool the butt connectors don't work so well but wire nuts don't require any special tool. Hope it works!


Easy to install. I installed the hitch as well so I had the bumper off which made running wires easier. You do have to run a wire to the battery but it's easy to run on this vehicle. I've done thousands of brake control installs and this is one of the easiest especially with the plugs.

2017 Dodge Ram Pickup

The hitch receiver & wiring kit for my '17 RAM ProMaster City was perfect. Installed easy & work great! Saved me a lot of money, BIGTIME!!!


This is second hitch from etrailer.
and received on time.
The best reason i buy from etrailer is the great video's
that show how to install.
Seems like there is always something that would hang up the install
if you did not view video.

2017 Ram ProMaster City

The first powered trailer light converter didn't last 5 months. I really don't know if it ever did work as the first time I used it it did not work. Ordered another and will see about this one.

2017 Ram ProMaster City

Product did not install as per instructions. The module was to be attached to the inner passenger side after quarter panel with double side tape. The space shower on the instructions and video is not there on our 2017 model. the harnes worked as designed.

2016 Ram ProMaster City

power wire for 118719 was 1' short. Otherwise, good.


The product was easy to install and works great the video was dead on and I didn't have access to a lift but it was still very easy to do. Great product.

2021 Ram ProMaster City

Following the instructions included, I found the harness with the plug was too short to reach the drivers side of the hitch, I had to lengthen that. other wise everything else went as instructed!


I watch the video that each trailer put online and it seemed easy enough and I was able to install it and begin pulling my trailer right away. It was the first time I’ve ever done any work on a vehicle before and it went together smoothly

2018 Ram ProMaster City

just had problem with retracted pin in plug not making connection but easy fix after locating problem


everything that I have ordered from etrailer has been spot on and high quality. thank you very much.


great product. easy install with you tube help.


Streamline service

2015 Ram ProMaster City

Good quality delivered on time and in good condition. Easy to install


Looks good but haven't installed it yet. Thanks for the prompt delivery, sooner than expected.


this is the 2nd time I have ordered, I wouldn't order from anywhere else. Very helpful.
Thank you

2016 Ram ProMaster City

easy to follow best price available


They guy was great got my return in email and the new one arrived Monday.

Show More Reviews

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

  • Does Install of Tekonsha Trailer Wiring Harness # 118719 Require Accessing Both Rear Taillights
    To install the Tekonsha trailer wiring harness part # 118719 that you referenced you need to be able to access both sides of the vehicle's taillights. This is because you need the turn signal circuit from both sides and either side isn't available on the opposite side if that makes sense.
    view full answer...
  • Does Battery Wire Need to be Ran to Install Trailer Wiring on 2021 Ram ProMaster City
    You do have to run a power wire up to the battery of your 2021 Ram ProMaster city to install the Tekonsha harness part # 118719. This is a pretty standard step now for trailer wiring since it allows your trailer wiring to be powered actually from the vehicle battery instead of the taillight wiring which prevents shorts from damaging the vehicle wiring as well as gives the trailer lighting more amperage. This wasn't the standard way to wire up trailer wiring a few years back but since vehicles...
    view full answer...
  • Does T-One Vehicle Wiring Harness For 2018 Ram ProMaster City Need to Connect to Battery
    To ensure it works properly at all times, you will need to connect the hot lead directly to the battery of your 2018 Ram ProMaster City when you install the wiring harness that fits, which is the following part: - T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118719 I have added a link below to an install of this harness on a similar model year ProMaster City which will detail the process for you.
    view full answer...
  • Does Spare Tire Affect Installation of Draw-Tite Trailer Hitch on 2016 Ram ProMaster City
    A full-size spare tire on your 2016 Ram ProMaster City will not affect the installation or fit whatsoever of the Draw-Tite Trailer Hitch Receiver # 75219. The reason is the hitch gets installed behind the bumper cover, as you can see by the linked installation instructions. So the spare tire of your van is not going to be a hindrance or come into play during the install. Along with the instructions I have also added a link to a video install for you to check out of the Draw-Tite Trailer...
    view full answer...
  • Can 12V Power Wire of Tekonsha T-One be Connected to 12V Outlet on a 2015 Ram ProMaster City
    That is a great question that a lot of people have been wondering about. The purpose of the black 12V wire that comes with the Tekonsha T-One # 118719 is to bypass drawing power off of your OEM wiring. If you were to tie it into the 12V accessory outlet at the rear of your 2015 Ram ProMaster City then it could possibly overdraw that circuit. To ensure that everything works properly and that you don't damage any OEM wiring on your vehicle I highly recommend running the power wire to your...
    view full answer...
  • What are Differences Between Curt and Tekonsha Harnesses?
    There are a couple of differences between the wiring harnesses for your 2016 Ram ProMaster. The biggest difference is the technology used. The Curt # C56270 uses what is called Surface-Mount Technology. Essentially what this does is almost eliminate the draw on tail light circuits. which traditionally draw the most amps. The Curt harness also has a maximum amperage of 7.5 amps per circuit on the stop and turn lights, while the Tekonsha # 118719 has a max amperage of 4.2 amps per circuit....
    view full answer...
  • 4-Pole Trailer Taillight Wiring Harness Recommended for 2020 Ram ProMaster City Van
    We'd be happy to help you out with that! We'd recommend the Tekonsha # 118719 4-pole taillight converter/wiring harness for your 2020 Ram ProMaster City. The harness/connector will provide basic lighting functions for your non-braked trailer. We recommend the Tekonsha model over the Curt # C56270 you'd looked at, because in our experience they're more reliable in the long run. Check out the linked install video that will walk you through the installation, step by step. Also, we've linked...
    view full answer...
  • Will the Curt T-Connector or T-One Disable Park Sensor Warning on a 2016 Ram ProMaster City
    The only trailer wiring harness I am aware of that disables the park sensor warning message on a Ram ProMaster City is the Mopar Trailer Tow Wiring Harness. The T-One Vehicle Wiring Harness part # 118719 and the Curt T-Connector Vehicle Wiring Harness part # C56270 will not disable the park sensor warning message so if you use either of these you may get an in-dash error message while in reverse with a trailer attached. This will not have an effect on anything but it can be rather annoying....
    view full answer...
  • Park Sensor Warning Message on a 2018 Ram ProMaster City While Reversing with Trailer
    I took a look in the owner's manual for your 2018 Ram ProMaster City and did not see any way to manually disable the ParkSense. More often than not, you can disable the parking sensors in the information panel on your cluster but I was not able to confirm this for your Ram ProMaster City. The sensors are supposed to automatically deactivate when the transmission is placed in reverse with a trailer connected but this is for Mopar wiring harnesses only. You can try turning the key ignition...
    view full answer...
  • Trailer Wiring Harness Recommendation for a 2015 Ram ProMaster City
    Both trailer wiring harnesses that you mentioned part numbers # C56270 and # 118719 have been confirmed as fits for your 2015 Ram Promaster City. Since we tend to have better luck with the Tow Ready brand I would recommend the # 118719. The price is also better for this harness we asll.
    view full answer...
  • Can Hot Lead From Wiring Harness be Run Inside Vehicle
    It sounds like you are referring to the hot lead for the Tekonsha T-One Vehicle Wiring Harness # 118719 that needs to be run up to the vehicle's battery. You can definitely route the wire inside your Ram ProMaster City as opposed to through the frame or underneath the vehicle. Every vehicle is a bit different, so the particular path you will need to take when routing the wire in this manner will depend on the interior of your ProMaster City. Ideally you will be able to loosen or remove...
    view full answer...
  • Does Trailer Wiring Install for 2018 Ram ProMaster City Require Running Wire to Vehicle Battery
    When installing trailer wiring in your 2018 Ram ProMaster City like the # 118719 you do have to run the power wire up to the battery to ensure your vehicle's wiring circuits are totally protected. Otherwise you run risk of damaging the circuit that powers the 12 volt power circuit you mentioned which would kill the trailer lighting and potentially damage the vehicle wiring. I attached an install video for this kit that shows it installed in a similar 2017 Ram ProMaster as yours that covers...
    view full answer...
  • Recommended Wiring Harness Kit for Towing with a 2018 Ram ProMaster City
    Yes, we do! The wiring kit I recommend purchasing to use with your Draw-Tite # 75219 on your 2018 Ram ProMaster City is the Tekonsha T-One # 118719. This plugs in behind your tail lights and draws power from your battery via the black wire. This bypasses all of the wiring on your ProMaster City so that if anything goes wrong with the wiring on your trailer it won't backfeed into your new vehicle. You also need a ball mount, hitch pin & clip, and a hitch ball to complete your towing setup....
    view full answer...
  • Troubleshooting Curt T-Connector Wiring Kit on 2015 Ram ProMaster City
    If the Curt T-Connector Vehicle Wiring Harness # C56270 on your 2015 Ram ProMaster City is sending those same signals whether your trailer is connected or you're using a circuit tester to check functions then it likely means the Curt wiring is bad if the lights on your ProMaster City are acting normal. You can verify this by testing the wiring going into and coming out of the Curt control module. If the wiring going in is operating properly but you get that abnormal operation on the output...
    view full answer...
  • Trailer Hitch and Wiring for a 2016 Ram ProMaster City
    For your 2016 Ram ProMaster City I recommend trailer hitch # C13215. This is a Class III trailer hitch with a 2 inch receiver rated for 350 pounds tongue weight and 3,500 pounds gross trailer weight. Since you plan on doing some towing I recommend etrailer ball mount kit # 989900. It comes with 2 ball mounts; one with a 3/4 inch rise or 2 inch drop and one with a 2-3/4 inch rise or 4 inch drop. It also includes a 1-7/8 inch ball, 2 inch ball, hitch pin with clip, and a storage bag. If...
    view full answer...
  • Parts Needed To Tow Trailer With 2018 Ram Promaster City
    To tow a small trailer with your 2018 Ram Promaster City you will need a hitch, trailer wiring, hitch pin, ball mount and ball. For the hitch, I recommend Draw-Tite Max-Frame Trailer Hitch Receiver - Custom Fit part # 75219 which is a custom fit hitch for the Promaster that bolt right up to the existing frame holes instead of drilling. The hitch is a concealed cross tube hitch so the only portion of the hitch that is visible once installed is the receiver tube. I have attached an installation...
    view full answer...
  • Recommended Trailer Hitch Receiver and Bike Rack for 2021 Ram ProMaster City
    For your 2021 Ram ProMaster City I recommend the Draw-Tite Max-Frame Trailer Hitch Receiver # 75219. This custom-fit hitch will be perfect for a bike rack and towing your trailer. It has a 2" receiver with a maximum gross trailer weight of 3,500 lbs and tongue weight of 350 lbs. Make sure to check your owner's manual for the towing capacity of your vehicle so you know what it is capable of. For wiring, the best option is the Tekonsha T-One Vehicle Wiring Harness # 118719. This plugs directly...
    view full answer...
  • Best Trailer Hitch Receiver, Vehicle Wiring Harness and Bike Rack For a 2020 Ram ProMaster City
    I recommend using the Draw-Tite Max-Frame Trailer Hitch Receiver # 75219 on your 2020 Ram ProMaster City. This hitch does not need additional stabilizing straps when carrying hitch mounted accessories. The Curt Trailer Hitch Receiver # C13215 recommends the use of Curt Cam Buckle Stabilizing Strap # 18050 when you use it with hitch mounted accessories such as a bike rack which you intend to use. I would recommend installing the Tekonsha T-One Vehicle Wiring Harness # 118719 at the same...
    view full answer...

Do you have a question about this Custom Fit Vehicle Wiring?

Info for this part was:

Employee Zack K
Video by:
Zack K
Employee Joshua S
Video by:
Joshua S
Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Jameson C
Expert Research:
Jameson C
Employee Jacob T
Video Edited:
Jacob T
Employee Wilson B
Updated by:
Wilson B
Employee Isabelle B
Updated by:
Isabelle B
Employee Alexander C
Written by:
Alexander C
Employee Brent H
Test Fit:
Brent H
Employee Ryan G
Test Fit:
Ryan G

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