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  1. Custom Fit Vehicle Wiring
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  3. Custom Fit
  4. Trailer Hitch Wiring
  5. 4 Flat
  6. Powered Converter
T-One Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector

T-One Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector

Item # 118278
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Custom Fit Vehicle Wiring

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118278 - Powered Converter Tekonsha Custom Fit Vehicle 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 OEM tow package harness - no cutting, splicing or tapping required. Call 800-298-1624 to order Tekonsha custom fit vehicle wiring part number 118278 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 for Factory Tow Package - 4-Pole Flat Trailer Connector. Custom Fit Vehicle Wiring reviews from real customers.
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  • Reviews (95)
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Tekonsha Custom Fit Vehicle Wiring - 118278

  • 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 OEM tow package harness - no cutting, splicing or tapping required.


Features:

  • Provides a 4-way flat trailer connector at the back of your vehicle to power your trailer's signal lights
    • Designed for use with a factory tow package
    • Compatible with 5-pole, 6-pole, and 7-pole adapters (sold separately)
  • Connects quickly and easily - no cutting or splicing of wires
    • Locate connection points in rear cargo area
    • 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
  • 1-Year limited warranty


Installation

This custom-fit T-One connector plugs into your vehicle's factory tow package wiring harness, which is located in your rear cargo area. You will have to remove the rear threshold plate and interior paneling to access this harness.


Once installation is complete, the 4-way 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.



118278 Tekonsha T-1 T-Connector - OE Replacement - 4-Way

Installation Details 118278 Installation instructions

This Product Fits The Following Vehicles



California residents: click here



Customer Reviews

T-One Vehicle Wiring Harness for Factory Tow Package - 4-Pole Flat Trailer Connector - 118278

Average Customer Rating:  4.9 out of 5 stars   (95 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 OEM tow package harness - no cutting, splicing or tapping required.

- 118278
by:

So far so good. Have yet to trailer anything. Wiring harness is pretty straight forward but takes a little patience taking off panels.



- 118278
by:
2016 Mazda CX-9

If you have a 2016 MAZDA CX-9 - this kit WORKS. It appears all 2016 Mazda CX-9's have the trailer wiring harness already installed. It is located behind the rear passenger side interior panel - the Tekonsha instructions show you how to get to it. You do NOT need to get a "generic" wiring kit as many of the other responses are suggesting. Just plug this one in and it works. I have submitted pictures below of the installation on my vehicle. I also installed the 76020 Draw-Tite Class 3 Trailer Hitch Receiver which fit nicely.



- 118278
by:
2016 Mazda CX-9

Nice product and easy to install the "Draw-tite Max-frame Trailer Hitch Receiver" with T-One wiring harness for Factory Tow Package- 4 Pole Flat Trailer Connector...



- 118278
by:
Mazda

Great service and Delivery, Justin B. Was very helpful with products, His knowledge and expertise answered All questions. product arrived a day early which was very pleasing and much needed !! Product installation videos made it a snap to install, and wire installation tools that came with hitch hardware made installing bolts in frame so easy. Using a strap to support exhaust was a great recommendation !! Every part fit perfectly and operated as specified. Wiring, Hitch and bracket took me approximately 2.5 Hrs. doing this on my driveway. These components were installed on my 2017 Mazda CX-9 AWD. I did not take any photos because what you see on E-trailers videos is exactly how it looks.



- 118278
by:

Took about 45 minutes to install. Just follow the installation video and you can't go wrong installing this.



- 118278
by:
2018 Mazda CX-9

I wish Etrailer would consult every company I shop with on how to create an amazing buying experience. From finding what you need, to installation videos - Perfection!



- 118278
by:

Followed videos which were for my exact vehicle. The videos are really helpful. Anybody can put the hitch on and install the wiring harness. I probsbly saved $600 doing it myself.



- 118278
by:

The hitch looks so nice and durable They shipped so fast And the price are fair I will recommend to anyone who is looking for a great hitch



- 118278
by:
2019 Mazda CX-9

I installed in about 45 min. Very easy to do if you follow along with the video. This is my second etrailer elect kit. Great product!!!



- 118278
by:

Harness was simple to install, and has worked great for last year.



- 118278
by:
2019 Mazda CX-9

Perfect match with the vehicle. Plugged right in and works! The installation video provides step-by-step instructions for pulling panels and removing anchors. The electrical installation took less an hour and looks clean.



- 118278
by:

One year in and this wiring harness is working like a charm. I would recommend it to anyone looking to hook up electrical to a tow vehicle. Instructions were simple with minimal tools required. If I need anything tow related etrailer.com is my first go to.



- 118278
by:
2019 Mazda CX-9

This kit installed seamlessly on our 2019 Mazda CX-9. The instructional video from etrailer perfectly walked me through step-by-step which was very reassuring, since I'd probably have been a LOT more delicate removing the necessary side panels in the back of the SUV without it. Just like the trailer hitch I purchased, the instructions were spot-on and made installation of this wiring harness an absolute breeze. etrailer has definitely set the bar on installation and support for their products.



- 118278
by:

truly plug and play. Only hard part was disassembling the interior of the car to get to the factory plug in



- 118278
by:

Well designed and built.



- 118278
by:

Easy peasy. 20 minutes taking your time. It was like Mazda designed it. Dealer wanted $600-$700 for receiver and wiring with installation. Out the door for [much less] with etrailer. I'd say difficulty was more like 3 stars.



- 118278
by:

Perfect fit, good video, easy install



- 118278
by:
2018 Mazda CX-9

Easy to fit on-line video instructions were very helpful. The included paper instructions were less helpful.



- 118278
by:
2016 Mazda CX-9

This is in reference to a 2016, Mazda CX9. This comment adds to the 2 previously posted comments. It deals with getting the interior panel to release. There are 2 screws that must be removed before attempting to remove the panel. One screw is at the top of the panel under the black plastic hook.The other screw is under a piece of plastic trim that must be removed where the lower chrome anchor is. Then remove the jack, and the other plastic parts near the jack. Once everything is removed, carefully start popping the trim panel off with a trim panel pry tool. Keep prying until you can reach the plug that part #118278 goes into.


Comments
It is only a 4-wire harness. I really need a five wire for my boat trailer. I wish ETRAILER had a five-wire.
Marty W - 10/07/2017



- 118278
by:
2016 Mazda CX-9

The hitch receiver is easier to install than the wiring harness, but that is only because I hate taking apart all the snap fasteners on interior panels. But, once removed, this simply plugs in and you are good to go. Like in the video, I secured the ground on the 10mm bolt. One tip is to pull out the trays straight up and with some good force to pull out the white retaining pins. Otherwise, you will have to pry them out using a forked interior panel pry bar, like the one in the video. Overall, this is a great product.


Comments
Awesome thank you!
R. H - 10/04/2018



- 118278
by:
2017 Mazda CX-9

I had ordered the recommended hitch and wiring install kit through the trailer rental place and found not only were there no instructional videos but the wiring kit they recommended for my vehicle make and model was incorrect. etrailer had the right wiring kit (at a lower price) and the most helpful instructional videos! Will recommend them every time in the future.



- 118278
by:
2020 Mazda CX-9

Installation and fitment went perfectly! The paper instructions were nothing compared to the installation videos on etrailer. I'm so happy with this purchase!



- 118278
by:

Watching the installation video prior to installing made the world of difference! I was able to install this within 20 minutes and was very easy. If I was to do this by the directions alone it would have taken 3x as long and would have been challenging!! Way to go etrailer, you guys are the best!! I purchased the bracket to install this outside the car but now contemplating whether to just keep it inside until I need to tow.



- 118278
by:

The hitch arrived quickly, I installed the wiring myself, this was very easy after watching your video. I had a local company install it, as I don't have a pit or hoist and I am way too fat to squeeze under this vehicle. the installation took 35 minutes. I am extremely happy with the product and the service.



- 118278
by:
2019 Mazda CX-9

Wiring harness plugs right into factory plugs. The BEST part, the etrailer howto video was perfect. It matched my year and model exactly and give me a very clear, detailed step by step on the installation, showing how to remove and replace all the panels and bits without damage.


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Ask the Experts about this Tekonsha Custom Fit Vehicle Wiring



  • Trailer Wiring Recommendation that Fits 2018 Mazda CX-9
    Actually the trailer wiring harness part # 118278 is a confirmed fit for the 2018 Mazda CX-9. I attached an install video for you to check out as well.
    view full answer...
  • Does Tekonsha Trailer Wiring Harness Fit 2018 Mazda CX-9 Grand Touring
    The Tekonsha trailer wiring harness part # 118278 is a confirmed fit for all models of the 2018 Mazda CX-9 so it does fit your Grand Touring model.
    view full answer...
  • Installing a Draw-Tite Hitch on a 2021 Mazda CX-9
    The Draw-Tite # 76020 does have a tech tip of needing to modify the heat shield as it does fit a few years of the Mazda CX-9. Some of the 2018 models did need this shield modified slightly to fit properly, but it looks like that may have been limited to that year. I have an install video we did on a 2020 CX-9 and there was no modification needed. As we have not had a 2021 to do an install on as of yet, I can't 100% confirm the need to modify the heat shield, but odds are you will not need...
    view full answer...
  • Best Trailer Wiring Harness for a 2014 Mazda CX-9 with Factory Tow Package
    I do have an option for you but the T-One Vehicle Wiring Harness for Factory Tow Package part # 118278 is not a confirmed fit for your 2014 Mazda CX-9. Instead, you will want to use the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector part # 118520 which fits models both with and without the factory tow package. The wiring harness that you originally asked about is only a confirmed fit for a Mazda CX-9 from 2016-2018 and will not work on your 2014. I have also attached an...
    view full answer...
  • Installing 5-Way Connector on 2016 Mazda CX-9
    There is not a 5-Way connector available that is designed to install on your 2016 Mazda CX-9. With this in mind, the best solution is still to install a 4-Way connector with the Tekonsha # 118278 and use the Wiring Adapter # 20036, which is what it sounds like you are doing. The harness and adapter will give you the 5-Way needed to connect to your trailer.
    view full answer...
  • Hidden Trailer Hitch Recommendation for 2019 Mazda CX-9
    The most hidden and best hitch option for your 2019 Mazda CX-9 is the Draw Tite hitch part # 76020 as only the hitch opening hangs below the rear bumper and it has a 7-way bracket built into it which will make mounting a 7-way like you are wanting as easy as possible. I attached an install video and picture for this for you to check out as well. For trailer wiring you'd need to start with a 4-way like the part # 118278 which installs easily and then you'll need to convert it to a 7-way...
    view full answer...
    Image 1 for
  • Trailer Hitch and Wiring for a 2021 Mazda CX-9
    The Draw-Tite Max-Frame Trailer Hitch # 76020 is going to be a great option for your 2021 Mazda CX-9. This hitch has a concealed cross tube and good towing capacities. It has a 2" receiver opening and includes an integrated mounting point that lets you attach a bracket for a 4-way like the T-One Vehicle Wiring Harness # 118278, which is the correct wiring harness for your CX-9. The T-One connector plugs into your vehicle's factory tow package wiring harness, which is located in your rear...
    view full answer...
  • Trailer Wiring Harness Recommended for 2012 Mazda CX-9
    Some vehicles are partially prewired at the factory for the trailer connector, but the 2012 Mazda CX-9 didn't have that provision. I'd recommend going with the Tekonsha T-One connector, part # 118520 as their hitch wiring harnesses seem to be a bit more reliable in the long term. If you haven't chosen a hitch yet, I'd recommend the Curt Class III, part # 13575. I've linked to installation videos that you might find helpful.
    view full answer...
  • Parts Needed to Tow Small Utility Trailer with 2017 Mazda CX-9 Equipped with 1-1/4" Hitch
    In order to pull a 4x6 utility trailer with your 2017 Mazda CX-9 you will need to add a wiring harness and ball mount/hitch ball combo. Starting with the wiring harness I highly recommend the Tekonsha T-One # 118278. This custom harness simply plugs into a factory port behind the passenger side trim panel for a complete "plug-and-play" install. This will provide you with a 4-Way connector to connect with and power the trailer's basic signal lights. I have attached an install video on...
    view full answer...
    Image 1 for
  • Trailer Hitch and Wiring for 2020 Mazda CX-9
    We have a Draw Tite Class III part # 76020 as a confirmed fit for your 2021 Mazda CX-9 that I would recommend highly as it's mostly hidden and has great towing capacities. Then for a custom trailer wiring harness we have the Tekonsha part # 118278 which installs easily and has a very reliable converter box. If you wanted to do some towing you might be interested in 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...
    view full answer...
  • Will T-One Connector Fit 2018 Mazda CX-9 With or Without OEM Hitch
    According to my research, and my contact at Tekonsha, the 2016 and 2017 CX-9 models both came with the connector for the T-One # 118278 as a standard. Since your 2018 Mazda CX-9 is the same generation it would be surprising if you didn't have that connector. I did check the online version of your owner's manual and it states on page 6-58 that the #8 "Trailer Hitch" fuse is only included on some models. You may want to check the left side of your fuse block compartment to make sure that...
    view full answer...
    Image 1 for Image 2 for
  • Recommendation for Adding 5-Way Trailer Connector to 2019 Mazda CX-9
    On your 2019 Mazda CX-9 there is a factory port behind the passenger side trim panel that accepts a custom 4-Way trailer harness plug. If this is what you are referring to when you mentioned that your vehicle has the trailer ready connector, then you will want to start with the Tekonsha T-One Wiring Harness # 118278. This will plug right into that factory port to provide you with a 4-Way connector. From there (or if you already have the 4-Way connector) I recommend simply adding the Tow...
    view full answer...
  • Which Curt Hitch Fits 2020 Mazda CX-9
    Yes, the Curt hitch part # C13284 that you referenced is confirmed as a fit for your 2020 Mazda CX-9. For trailer wiring the Tekonsha part # 118278 is a confirmed fit and easy to install as well! I attached install videos for both of these for you to check out too. If you wanted to do some towing you might be interested in 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...
    view full answer...
  • Is There a Class II Hitch with 2 Receiver Available for the 2020 Mazda CX-9
    I have a solution for you, but there is not a Class II hitch with a 2" receiver available for the 2020 Mazda CX-9. Instead, you can use a Class III hitch like the Draw-Tite # 76020 which has a 2" hitch receiver like you're seeking and also has a hidden cross-tube like the EcoHitch so it's going to keep the clean factory look on your CX-9. If you're going to be towing with your CX-9, you'll also need a wiring harness, ball mount and hitch ball. For the wiring harness I recommend using the...
    view full answer...
  • Recommendation to Install 5 Pole Connector on 2017 Mazda CX-9
    If your 2017 Mazda CX-9 already has a 4-Way connector installed, I recommend using the Tow Ready 4 Pole to 5 Pole Trailer Wiring Adapter # 20036. This will easily change the 4 pole flat on the vehicle to a 5 pole flat. The additional blue wire will simply get spliced into the reverse light wire on the CX-9 with the included quick splice connector. You can use a circuit tester like # 3808 to determine which wire is the reverse wire on your vehicle. If you do not have a 4-Way already installed...
    view full answer...
  • Can the Tekonsha Wiring Harness # 118278 Fit a 2016 Mazda CX-9
    The Tekonsha Wiring Harness # 118278 is only confirmed to fit 2016 Mazda CX-9's with a factory tow package. If you do not know if you have a factory tow package, you can check behind your rear trim panels to see if you find the factory connectors. If you find factory connectors, you can use a circuit tester like part # 40376 to probe the connectors to see if they are active with taillight functions. If not, you will have to check with your dealer to see if the factory connectors can be...
    view full answer...
  • 4-Way to 5-Way Adapter Recommendation for 2016 Mazda CX-9
    The back up circuit will be found at the reverse light harness of the vehicle. You will need to find the circuit that carries 12 volts only when the vehicle is in reverse that runs to the reverse light circuits of your 2016 Mazda CX-9. For an adapter to convert the 4-way to a 5-way you will want the part # 20036. To find the circuit you will need a tester like the part # PTW2993.
    view full answer...
  • Determining Towing Capacity of 2017 Mazda CX-9 with Draw-Tite Class III Trailer Hitch
    The Draw-Tite Class III Max Frame Receiver Hitch # 76020 referenced in your question is confirmed to fit your 2017 Mazda CX-9. As you mentioned, the 2 inch hitch features a 4,500 pound towing weight capacity and a 675 pound tongue weight capacity. I took a look at the online owner's manual for your CX-9 and found a towing capacity of 3,500 pounds. A towing setup is always going to be limited by its weakest component. This simply means that the weight of your trailer will need to fall...
    view full answer...
  • Recommended Hitch and 4-way Connector for a 2021 Mazda CX-9
    The hitch that I recommend for your 2021 Mazda CX-9 is the Draw-Tite Max-Frame Trailer Hitch Receiver # 76020.This hitch has a bolt-on, no-drill installation and will provide you with a 2" receiver opening which is the most common size used for hitch mounted accessories such as bike racks, cargo carriers and ball mounts. This hitch also includes a bracket you can use to mount the Mounting Bracket 4-Pole Flat # 18144 on for mounting your 4-way connector to your hitch. The 4-way wiring harness...
    view full answer...
  • Trailer Wiring and Hitch that Fits 2022 Mazda CX-9
    We have trailer wiring that fits your 2022 Mazda CX-9 with the Tekonsha kit part # 118278 but the Curt you mentioned is not a fit for your vehicle. This will work great with the Draw Tite hitch you plan on installing on your vehicle as well # 76020.
    view full answer...
  • Do I Need To Add Any Noise Reduction Material Between The Receiver and My 2021 Mazda CX-9?
    The Draw-Tite Max-Frame Trailer Hitch Receiver # 76020 will be tightly bolted to the chassis on your 2021 Mazda CX-9. There is no need for any type of insulating material to go between the receiver and the frame connections. I have not seen any complaints in either our expert questions or customer reviews describing any noise caused by the receiver itself. The Tekonsha T-One Vehicle Wiring Harness # 118278 will give you a 4-way flat connector to control the lights on a trailer you are...
    view full answer...
  • Compatability Of The Curt Trailer Hitch Receiver With The Hands Free Liftgate On 2021 Mazda CX-9
    We have received reviews for the Curt Trailer Hitch Receiver # C13284 confirming that the hands-free liftgate will operate with the receiver installed on a 2021 Mazda CX-9. You should not have any issues using yours on your CX-9 but as a general guide line I do recommend testing it after the receiver is installed as generally one side may work better at sensing the foot movement. The Tekonsha T-One Vehicle Wiring Harness # 118278 will allow you to have a 4-way flat trailer connector by...
    view full answer...
  • Hitch and Wiring Harness for a 2017 Mazda CX-9
    The Draw-Tite Max-Frame Trailer Hitch Receiver item # 76020 you were looking at is confirmed to fit your 2017 Mazda CX-9 and we have plenty of stock (2/22/22). This hitch is custom fit and bolts to your CX-9 with included hardware. It does not require any drilling or welding. I have attached an installation video and a picture so you can see what the hitch will look like once installed. If you are going to be towing with your Mazda then you'll also need the Tekonsha T-One Vehicle Wiring...
    view full answer...
    Image 1 for
  • Parts Needed to Add 5-Way to 2020 Mazda CX-9
    To install a 5-way on your 2020 Mazda CX-9 will require you to first install a custom fit 4-way like the # 118278 and then use a 5-way adapter like part # C57187 which plugs into the 4-way and requires you to run the extra wire to the reverse light circuit of the vehicle. Since 5-ways aren't nearly as popular as 4-ways they aren't available as plug and play options.
    view full answer...


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Info for this part was:

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Employee Andrew K
Video by:
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Employee Kathleen M
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Video by:
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Edited by:
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Employee Chris R
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