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

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

Item # 118778
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Custom Fit Vehicle Wiring

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118778 - Powered Converter Tekonsha Custom Fit Vehicle Wiring
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Customer Photos

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. Call 800-298-8924 to order Tekonsha custom fit vehicle wiring part number 118778 or order online at etrailer.com. 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 (17)
  • Q & A (25)
  • Photos
  • Why etrailer?

Tekonsha Custom Fit Vehicle Wiring - 118778

  • Custom Fit
  • Trailer Hitch Wiring
  • Tekonsha
  • 4 Flat
  • Powered Converter

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.


Features:

  • 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 point on the back wall of the cab
    • Plug in T-connector
  • 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


Specs:

  • Maximum amperage:
    • Stop/turn lights: 4.2 amps per circuit
    • Tail lights: 7.5 amps per circuit
  • 1-Year limited warranty


Installation

This custom-fit T-connector plugs into your vehicle's wiring harness. The connection point for the T-connector is located towards the center of your vehicle on the back wall of the cab. The converter plugs into the gray 12-pin tow plug. Once you've plugged in the connector, insert the included fuses into your fuse panel as indicated in the instructions.


Once installation is complete, the 4-way flat connector will be stowed beneath your vehicle, under the bumper. Secure the connector with the included cable ties.


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.



118778 Tow Ready T-1 T-Connector - 4 Wire - Modu-Lite

Installation Details 118778 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 - 118778

Average Customer Rating:  4.5 out of 5 stars   (17 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.

- 118778
by:
2017 Honda Ridgeline

Just finished installing the T-One Trailer connector on my 2017 Honda Ridgeline RTL-T. Installation was not too difficult. Instructions were sparse with respect to exactly how to locate and access the plug on the back firewall. Also the instructions on how to remove the cover on the plug under the rear bumper were not very helpful. A short video on these tricky things would help immensely. How and where to attach zip ties or sticky tape is not needed. Beyond that I am very pleased with my trailer connector. 561181



- 118778
by:
2019 Honda Ridgeline

The four wire trailer kit installed successfully on a 2019 Honda Ridgeline RTL-T. Installing the black box module is easy once Honda's connector is located behind the driver's side rear seat. Carefully remove plastic panel (near floor) next to where seat belts bolt to frame. Panel has two flexible tabs near top - one on either side of the seat belts - that must be carefully moved a bit to release the panel at top. Check other reviews for photos on locating the cable (it's the thicker one) and connector that plugs into black box. The connector will be tucked behind some thin insulation material. Gently pull it down to expose connector. Its cable shroud is tied to back wall at one point but there's enough slack to connect to module. Secure the module to your taste, install three fuses under hood, and finally connect up trailer cable (very easy). Don't forget to grab the boat and trailer then head to the lake. The kit has high quality parts. 643239



- 118778
by:
2019 Honda Ridgeline

The product is high quality and the instructions are very good. It took me about an hour to install and worked perfectly when complete. I would recommend it. The only difficult part was finding where Honda hid the gray plug for the powered converter module behind the back seat and behind the sound deadening material.. Be patient and persistent and you will find it. etrailer is always my “go-to” supplier for anything towing related. 633409


Comments
Works fine. I recommend it.
Gary - 04/20/2020

73706

- 118778
by:
2019 Honda Ridgeline

SO far very poor instructions. I mean really the photos do not match my truck, they are not clear at all. They make it sound so simple, but I still cannot find the harness connector in the back seat of my brand new truck. 595987


Comments
I have linked you to instructions for the Curt application for your 2019 Ridgeline. Curts photos and written description are much more clear and easier to understand, and should help you complete the installation. The Curt harness looks a bit different than the Tekonsha model you purchased, but they would install in the exact same manner.
-- Mike L - 01/10/2019

48405

- 118778
by:

Product was expected. Easy installation instructions clear. Looks professional. 822657



- 118778
by:

Working great use it once a week 809357



- 118778
by:

Good sale , good item. 5 stars across the board. Item was plug and play. Really fits perfect. Super fast shipping. 790101



- 118778
by:
2019 Honda Ridgeline

The trailer turn signal control module kit worked perfectly when installed and still does a year later. Honda wanted over $200 for the kit. E-trailer's kit was less than $40 dollars. Couldn't be happier! 785563



- 118778
by:

No problem at all other than having to remove to back seat only to find out it was right where the instructions said it was. 771115



- 118778
by:
2018 Honda Ridgeline

Perfect fit!Great price!Good instructions.Wish that Honda could have made it easier to get to the hidden wiring though. 765617



- 118778
by:

Product worked just fine after I figured out how to get the cover off of the connector at the back of the truck. I did use information from the etrailer website to conquer it. 739611



- 118778
by:

The wiring at rear hitch was easy and simple. Finding the connection behind the rear seat involved removing the entire seat bottom and back to make a simple connection of the converter. Once that was done the real problem came with trying to follow the fuse placements. After consulting the we then owners manual , was able to figure it out 703320



- 118778
by:

Great product. Horrendous instructions. The instructions have one picture to show where to mount the module. In black and white! I could not find the connector for the module for my vehicle. Called support two separate times and could not find it. Finally through another review there was more detailed information. There really needs to be 1st hand knowledge on how to install these for all different models. I figured since it was a for a honda it would show me exactly where to go. But all in all figured it out. Works fine. UPDATE the instructions with color DETAILED pictures! 669808



- 118778
by:
Honda

Parts worked great and a lot less than the $400 Honda wanted to charge. Parts fit as advertised. I'm very satisfied. 651392



- 118778
by:

The support that eTrailer provides for their products is unequaled. Shipping is quick. Thanks, eTrailer. - Ed 635180


Comments
It does didn’t work, there was no place to plug in the module like the photo showed I can only assume that there is a difference between the Sport model and the regular Ridgeline.
Edwin - 04/26/2020

74180

The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # 118778 is compatible with 2017 - 2020 Honda Ridgeline all styles including the Sport. The black box module will plug into the 12 pin connector. First, remove the rear seat trim panel to access the connector area. The 12 pin vehicle tow plug connector will be located near the green relays on the driver’s side. The square plug of the towing harness will plug into the factory gray plug shown in the instructions with an arrow pointing to it. There is a cap on this plug that needs to be removed by sliding it rearwards. It has locking tabs as well so press down on those and that should remove the protective cap carefully.

-- Heather A - 5/21/2020


- 118778
by:
2019 Honda Ridgeline

etrailer is my place to go whenever I need towing harnesses, wiring, etc. Always professional and great service. 605322



- 118778
by:

seems to be a good product at a good price....however...your 'install video' says A) open the rear door B) locate the receptacle and plug in the device..... There is a lot of unexplained hard work to get from A to B....like remove the entire back seat....etc.....at least 1/2 hour each way....... 577741


17
17

Ask the Experts about this Tekonsha Custom Fit Vehicle Wiring

  • No Trailer Running Lights On a 2019 Honda Ridgeline with T-One Vehicle Wiring Harness 118778
    I called Tekonsha and they said they have had one other customer with this issue while using the T-One Vehicle Wiring Harness part # 118778 on a 2019 Honda Ridgeline. The cause of this issue was a bad converter box so that may be what is causing your running lights not to work as well. I also took a look through the instructions and compared them to the Curt T-Connector Vehicle Wiring Harness part # C56365. It looks like each manufacturer recommends installing fuses in different places...
    view full answer...
  • Connector Location for T-One Black Box on a 2019 Honda Ridgeline
    Thank you for the pictures! It looks like you found the connector for the pigtail with the 4-Way from the T-One # 118778 on your 2019 Honda Ridgeline. The reason that you are having trouble finding the connector that the black box plugs into is because you aren't quite looking in the correct place for it. The Tekonsha picture in the instructions doesn't do a great job at explaining where to look but the Curt T-Connector # C56365 instructions have some great pictures for this. I have...
    view full answer...
  • Locating 12 Pin Plug to Install Trailer Harness in 2019 Honda Ridgeline
    What we have found is that when installing a wiring harness such as the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118778 in a 2019 Honda Ridgeline, that 12-pin plug you are referring to can be frustratingly difficult to find and not exactly where the directions always say it is. We have had customers tell us that on some models of their Ridgeline they were required to actually remove the rear seat (instead of just fold it up) and remove the back trim (on the...
    view full answer...
  • Differences in Tekonsha #118778 & Curt #C56365 for 2019 Honda Ridgeline
    Curt went a slightly different route when they designed their trailer wiring kit for your 2019 Honda Ridgeline than Tekonsha did when they created the # 118778. The fuse is there to protect the converter box in case of a short on the trailer wiring, which this doesn't surprise me as Curt's boxes have proven to us to be slightly more susceptible to a short causing them to fail than Tekonsha. The extra ground is harder to speculate but it seems they found too that it worked better with a...
    view full answer...
  • Help Finding Gray Connector on 2019 Honda Ridgeline to Install Trailer Wiring
    The Tekonsha pictures in the instructions for the # 118778 don't do a great job at explaining where to look but the Curt T-Connector # C56365 instructions have some great pictures for this. I have attached a clip from the instructions which shows that the location is a little further back behind another panel just to the left of the green relays (pictures J, K, L, and M). I have attached links to instructions for both the T-One and T-Connector so you can compare them with what you see...
    view full answer...
  • Trouble Locating 12-Pin Connector for Black Box On a 2017 Honda Ridgeline
    It can indeed be difficult to locate the correct pigtail that is needed for the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # 118778 on your 2017 Honda Ridgeline but I assure you this is present. That said, others have had better luck finding the connector after removing the entire seat bottom which is more than required but will make things easier. If you still need help I have attached for you a write-up a fellow customer did that breaks down the process to...
    view full answer...
  • Where Is the Inside Connection for the T-One Vehicle Wiring Harness On a 2020 Honda Ridgeline
    In regards to the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # 118778 which is a fit for a 2020 Honda Ridgeline, there will be two connections one inside the vehicle and one outside. These locations will both be listed in the installation instructions. I have however attached for you below a snip of the instructions which points out the first connection.
    view full answer...
  • Best Trailer Wiring Harness for 2019 Honda Ridgeline
    The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118778 is the best choice to add a wiring harness to your 2019 Honda Ridgeline because it is a simple installation that will only require you to make a plug-in connection at the rear of your vehicle and install provided fuses. Additionally, the harness manufacturer, Tekonsha, has a very strong reputation for creating high-quality, reliable wiring products. I have added a link to a video review of this harness for you...
    view full answer...
  • Installation Instructions for the Tekonsha Wiring Part # 118778
    I currently do not have any install videos of the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # 118778 on the Ridgeline even in different years. I have linked the instructions for you and overall it is not a very involved installation. The plug and play nature removes the need to cut, splice or modify your factory wiring.
    view full answer...
  • Installation of Wiring Harness on 2019 Honda Ridgeline
    This can be a bit tricky but it sounds like you might be looking in the wrong spot on your 2019 Honda Ridgeline to install the T-One Vehicle Wiring Harness # 118778. The directions don't do a great job of making this more transparent but the connector should be directly to the left of the connectors with the green relays which sounds like the one you have found. It may take some more digging to pull this connector out but you should be able to find and locate it on the side of the connector...
    view full answer...
  • Troubleshooting No Trailer Running/Tail Lights with T-One on a 2019 Honda Ridgeline
    If you aren't getting running/tail lights on the T-One # 118778 installed on your 2019 Honda Ridgeline then I recommend checking the following: First, make sure that you turn the headlights on for your Ridgeline prior to testing (this has been forgotten by other people so I felt it necessary to mention). Also check the vehicle side connectors to make sure that nothing is damaged or bent. If you're still having issues then check the fuses in the following positions: Position...
    view full answer...
  • ModuLite Connector Location for T-One Wiring Harness for 2019 Honda Ridgeline
    The pictures that come with the installation instructions for the T-One # 118778 are kind of the end result of finding that wiring connector. If you look at the pictures I attached from the equivalent T-Connector # C56365 from Curt you get more of a step-by-step process in locating the connector for the ModuLite. We also have some customer reviews on the T-One page that you can use to help you locate this connector. We don't have any videos right now of either kit on a 2019 Honda Ridgeline...
    view full answer...
  • How to Remove Tow Plug Cap to Install 4-Way Harness on 2018 Honda Ridgeline Sport
    Thank you for the photo, it was helpful. From that it simply looks like you need to remove the locking tab of the tow plug on your 2018 Honda Ridgeline. The fastener at the top needs to be removed (what the arrow is pointing at) by sliding it rearwards. It has locking tabs as well so press down on those and that should remove the protective cap on the tow plug and you can complete your installation of the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118778. Once...
    view full answer...
  • How to Install Wiring Harness in 2019 Honda Ridgeline
    The installation of the T-One Vehicle Wiring Harness with 4-Flat Trailer Connector # 118778 on your 2019 Honda Ridgeline is a bit different because it uses a black box module, but it is still a straightforward install. What you will need to do is connect the black box module into the 12-pin tow plug that will be near the center of the back wall of your '19 Ridgeline's cab. Once you mount that, you'll need to look under the hood of your Ridgeline and find the fuse panel and insert the...
    view full answer...
  • Are Fuses Required for Installation of 4-Way in 2019 Honda Ridgeline
    The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118778 that fits your 2019 Honda Ridgeline has fuses and they are required for this particular installation. Thankfully the linked instructions make it very clear where the three fuses (which are included) need to go during the installation of this harness. Under the hood of your Ridgeline find the fuse panel and insert the pair of 7.5 amp fuses in Position 6 and Position 7. Following that you will install the 20 amp...
    view full answer...
  • Where Does Trailer Wiring Install on 2019 Honda Ridgeline
    I attached a picture that shows what both connectors on your 2019 Honda Ridgeline look like for installing the Tekonsha wiring kit part # 118778 that you referenced. The picture with the letter A on it is the 12 pin connector located near the back wall of the cab and the one with the letter D is the connector under the rear bumper by the driver's side.
    view full answer...
  • Recommended 4-Way Flat Wiring Harness for a 2019 Honda Ridgeline
    If you are looking for only a 4-Way Flat connector for your 2019 Honda Ridgeline then I recommend the Tekonsha T-One # 118778 because it has higher amp ratings than the Curt option and we have found the Tekonsha wiring units to be the most reliable out there. This connector gives you the basic lighting functions that you need for a smaller trailer and can be mounted using the Tow Ready # 18144 and a no-drill bracket like part # 18140. Since you have a pickup I do recommend installing...
    view full answer...
  • How to Install the Tekonsha Wiring Harness #118778 on my 2020 Honda Ridgeline
    I've got some answers but unfortunately we have not had the opportunity to install the wiring harness here at etrailer yet. I have linked the instructions for you that will have some pictures for you as a guide. I will also try to explain what you are looking for. For the large black box you want to look behind the rear drivers side seat. This location will be all the way down where the floor and rear wall meet. For the plug on the rear of the vehicle you will be looking right...
    view full answer...
  • How to Reset my Honda Ridgeline After Installing the Tekonsha T-One Harness Part # 118778
    To reset the system after installing the Tekonsha T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # 118778. Just return the ignition settings to the same as you would to park the Ridgeline. This will reset the electrical system and it will recognize the added wiring harness.
    view full answer...
  • Is Powered Converter Needed for Installing Trailer Wiring on a 2019 Honda Ridgeline
    The powered converter is what will send the actual power to the trailer connector so you will need to install it on your 2019 Honda Ridgeline whether you're installing the 4-Way flat or the 7-Way connector. I recommend going with the Tekonsha kits, 4-Way Part # 118778 or 7-Way Part # 118288, simply because we have found them to be the most reliable option. I'm attaching links to the installation instructions as well as our ball mount selection and a helpful article about choosing a ball...
    view full answer...
  • How To Install a 4-Way Trailer Wiring Harness On a 2020 Honda Ridgeline
    The T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # 118778 is all that is needed to tow a trailer with 4-way using a 2020 Honda Ridgeline. It does indeed require a connection inside the vehicle. Please note, if the vehicle is pre-wired for a 7-way it will also be pre-wired for a 4-way.
    view full answer...
  • Trailer Wiring Harness Recommendation for 2019 Honda Ridgeline
    For your 2019 Honda Ridgeline the trailer wiring harness I recommend is the Tekonsha part # 118288 if you need a 7-way or part # 118778 for if you need a 4-way. These are the best wiring harness solutions as the Tekonsha brand is the most reliable option currently available due to their higher quality converter boxes. If your trailer has a 7-way and brakes you'll need a brake controller to activate them for that our best option is the P3 # 90195. This is a proportional brake controller...
    view full answer...
  • Recommended 4-Way Trailer Connector for a 2018 Honda Ridgeline
    I do have an option for you but the T-One Vehicle Wiring Harness part # 118384 is not a confirmed fit for your 2018 Honda Ridgeline. Instead, you will need to use the T-One Vehicle Wiring Harness part # 118778 which plugs into a pre wired connector under the rear bumper. There is also a converter box that gets installed inside the cab which you can see from the attached install instructions. Unfortunately, there is no adapter that will allow you to use the T-One Vehicle Wiring Harness...
    view full answer...
  • Does Aftermarket Trailer Wiring for 2019 Honda Ridgeline Piggyback Off of Taillight Wiring Harness
    The trailer wiring harnesses we carry for the 2019 Honda Ridgeline do not piggyback off of the taillight circuits of the vehicle like some of the T-one style harnesses do. Our harnesses like the Curt # C56366 plug into factory wiring ports already present at the rear of the vehicle. So you'd be utilizing wiring on the vehicle that was intended to power trailer taillights. With this setup there are several fuses and relays that need to be plugged into fully activate the wiring. If you...
    view full answer...
  • Will Rampage SuperBrite LED Tailgate Light Bar # RA960134 Work on 2019 Honda Ridgeline
    The Rampage SuperBrite LED Tailgate Light Bar # RA960134 that you referenced is really a universal product that should work great on your 2019 Honda Ridgeline. The light bar simply mounts with the included 3M tape between the rear bumper and tailgate. It uses a standard 4-Way connector for power so as long as your Ridgeline is equipped with a 4-Way flat trailer connector this will plug right in. If not you can add one with the Tekonsha T-One # 118778 that will plug into a factory port...
    view full answer...

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Info for this part was:

Edited by:
Lindsey S
Expert Research:
Jameson C
Installed by:
Cole B
Updated by:
Alexander C
Updated by:
Isabelle B
Written by:
Ronnie R

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