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Transforming your vehicle into a towing machine has never been easier thanks to the T-One Vehicle Wiring Harness. Install a 4-way trailer connector on your vehicle quickly and hassle-free. This custom wiring harness plugs directly into your vehicle’s existing wiring, making it a straightforward process to navigate. With the included Powered ModuLite, you won’t have to worry about overloading your vehicle’s wiring system, providing peace of mind every time you hitch up.
For drivers navigating various trailer types, the T-One Harness's powered converter opens a world of possibilities. It seamlessly integrates with your vehicle’s wiring, allowing compatibility with 5-pole, 6-pole, and 7-pole adapters. Whether you’re towing a compact trailer or a larger setup, this harness ensures your vehicle and trailer signals sync perfectly, empowering you to hit the road without a second guess.
Dreading the days of scrambling for the right fit? Say goodbye to those headaches with the T-One Harness. Designed to be a custom fit for your specific vehicle model, this harness nestles perfectly behind the tail lights in your car's cargo area. No two vehicles are quite alike, and with this tailor-made harness, you are on the road knowing everything fits like a glove.
Avoid the pitfalls of overloaded circuits with the integrated ModuLite Power Module. Designed as a tail light converter, it combines brake and turn signals into a two-wire system compatible with most trailers. Not only does this alleviate stress on your car’s electrical system, but it also bypasses those pesky electrical routes that can lead to failures, offering you unfettered reliability on the go.
Whether you’re navigating through rain-soaked roads or dusty trails, the T-One Harness has your back. Constructed with 16-gauge bonded wire, it’s engineered to withstand the elements, offering enduring performance wherever you travel. The included dust cap protects unused connectors, ensuring you’re never caught off guard by weather-related malfunctions.
This custom-fit T-One connector plugs into your vehicle's wiring harness, located inside your trunk or cargo space, behind the tail lights on both the driver's side and passenger's side. You will need to remove some interior trim or carpeting to access this harness. 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.
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.
This will not affect how the tail lights on your vehicle operate.
California residents: click here
Very fast delivery!.. Nice packing and looks to be a pretty install.
Fantastic. Keep up the good work. I'll be back.
Excellent shipping, packaging and service.
Follow the directions and the install was a success. Everything worked on first test.
I have not installed the trailer hitch yet, but the instruction are very good, the product arrived in less time than expected and was in grest shape. I won't hesitate in ordering from etreailer again.
I was pleasantly surprised by the rapid processing and delivery of my order. The product was of top quality. I was informed that my delivery method was upgraded without cost to me and resulted in a faster delivery.
I will reccomend your company for any future orders.
Worst instruction sheet ever!Item may be good. Have not had enough time to gauge life span but it does do what it is supposed to but the instruction sheet is the worst. Once you decipher the instructions it installs easily.
Wiring harness was as described. Very easy to install. Workers great. Received item very fast. Would buy again from etrailer.
easy install, I took my time about an hour and 15 minutes. Hardest part is getting into the small area's of a Toyota to plug in the harness.
Real easy to install, at the beginning I thought it was hard to install, but after watching the video provided it was a piece of cake.
Julio and Pepelui of Buena Park, CA
I loved the fact that the harness plugged right into the factory wireing. Instructions and pictures were great. Took a little over an hour to install. Will definitely buy from etrailer again.
Product does what it's supposed to do. Huge pain to run a power wire from the trunk area to the battery up front, but that's not this product's fault. That's what happens when you install a towing set-up on a vehicle that really wasn't designed for it.
Only thing this product didn't have enough of was zip-ties. They give you 5 or so, but when you run a power wire under your car, I felt the need to secure it better in certain places, so I used an additional 10 or so of my own. Not a huge deal though as I think zip ties are as crucial to have on hand as duct tape.
Idiot proof connectors. A pain to run the wire to the front, but easy enough. I used the rubber grommet on the left side of the cargo area, just behind the rear seat, and stayed on the left side right up the front wheel well into the motor compartment. Take your time. Glad I didn't pay for a tow package. Everything you need in the kit. 9.9 out of 10
Easy wire hookup. Running the wire to the battery under the vehicle took the most time. You'll need extra wire ties to make sure the wire doesn't sag. Instruction said to run the wire through a grommet in the storage compartment. This will not work if you have dual exhaust. Ran the wire through a grommet just behind the back seat.
At this point, I have only just installedthe hitch and wiring. The hitch was installed very easily and the on-line video at etrailer.com was very helpful (actually, the video was a primary reason for purchasing from this company). Hitch looks very good.
The trailer wiring was relatively easy to install. As others have commented, the trickiest/most time consuming part was getting the black (power) wire to the front of the car and the battery.
Overall, very happy with my purchase. The price was as good as I could get anywhere, the on-line video, and (free) delivery as promised are very positive for me. Would purchase from e-trailer again and will recommend to others.
Great product. Installation was not too difficult, instructions was easy to follow. Team at Trailer was very helpful.
I have a 2017 Mazda 3. I ordered the product because I was hesitant about splicing into my car’s wires. This wiring harness made things a lot easier. I watched a YouTube video to get a quick idea of how to do it. The only thing I did different was I ran the wire which connects to the battery through the inside of my car. The wire runs from the trunk, easily squeezed between the rear seat, tucked into the floor panels by the doors, goes up near the driver side, through a small pre-existing gap in the body and to the battery. No drilling though the firewall, no need to go beneath the car. See photos for reference.
Great part, great service
Keith 
5/24/2025
It does exactly what it was designed for.
We really like the hitch we ordered for our Camry. It was extremely easy to install. Fit perfectly!
My second hitch purchased from etrailer for a Mazda hatchback (first '02 Protege5, now '15 Mazda3). Both good experiences.
Very easy hitch install, the inclusion of the fish wires for the frame hanger bolts is a stroke of genius. Don't be afraid of the exhaust isolators, just spray some soapy water and support muffler with a jack or strap. If you can change a flat tire then you can work a wrench well enough to do this in an hour.
'14-15 Mazda3 has a couple of things making wiring easy to integrate. There's a grommet in the left rear quarter floor that's perfectly placed. Just trim some electrical tape to allow an opening, clip the new connector near the lighting adapter & reconnect inside after fishing from outside. I ran power neatly along driver's side rocker & out through the firewall. It's both easier and less vulnerable, just fish one more wire through the mass that exits above the driver's left foot. (Just DO NOT use anything sharp, you don't want to nick any wires and short something out). Finally the battery on my car already had several open connections to use right at the positive terminal, each protected by a fusible link no less! (See photo.) All I needed to add was an M6 stainless nut to connect the new wire.
Only a couple of minor downsides:
Aesthetically this is one of the uglier installs, mostly because the 3's huge muffler is right against the rear valence, leaving no room to tuck anything out of sight. My Protege5's hitch was entirely hidden except for the receiver. Here, unless you're willing to butcher your bumper cover (assuming there's a hitch made to fit that way) you're stuck with what you see in my picture. I saw the round-tube alternative on another similar car and it looked a little better, but that one requires support straps for a rack with any carrying capacity.
Design-wise I ran into one surprisingly annoying thing the first time I went to insert my drawbar. The hole in the receiver for the hitch pin is set really close to the hitch frame, and there's a gusset plate on top, which leaves basically no room for the clip that secures the pin. My existing clip didn't fit at all until I ground the ends a little. The clip that came with the new hitch sort of fit, but only jammed up against the hitch so hard that it scratched right through the protective powder coat. Weird in a product from such an experienced manufacturer, but easy to rectify.
All equipment was delivered on time. Hitch, wiring harness, receiver and ball. Watched video's on installation of harness and hitch. Went down to my garage and installed both with the help of my girlfriend. Very satisfied with the products and the installation. etrailer supplied the goods and the knowledge. I am very happy that I went this route.
It still works after a year.
Hitch installed easily on my 2014 Toyota Corolla.
Wiring had poor instructions in the box but the video posted on etrailer’s site answered my questions.
No issues and everything worked.
Thanks.
This was a good recommendation from the etrailer expert. Installation was straightforward (although a little more involved than I remember from last time. He told me it is more reliable than my Curt product that had failed.
etrailer is a company I always look forward to dealing with.
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Christopher
11/28/2021
Still works great. Got exactly what I paid for. Extremely satisfied!