T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
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2004 Lexus LS 430
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2004 Lexus LS 430
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Say goodbye to the hassle of complex wiring setups. The T-One Vehicle Wiring Harness from Tekonsha offers a plug-and-play solution that connects directly to your vehicle's existing wiring, providing a seamless connection to your trailer's signal lights with a 4-way flat trailer connector. This makes getting on the road quicker and ensures a clean, professional installation with minimal effort.
Traditional wiring setups can overload your vehicle's electrical system, but not with the T-One's built-in ModuLite. This powered converter module connects directly to your car battery, ensuring your trailer's lights are powered without putting stress on your vehicle's circuits. It's designed to handle the amperage for both stop/turn lights (4.2 amps per circuit) and tail lights (7.5 amps per circuit), ensuring reliable performance on the road.
When it comes to vehicle compatibility, this harness shines. It's custom fit for specific vehicles, meaning you don't need to cut or splice wires. Located inside the trunk and behind the tail lights for easy access, it’s perfect for those who want a straightforward, damage-free installation. Just remove a bit of interior trim, and plug it in for a quick setup.
Durability is key for a dependable connection, and this harness delivers with its 16-gauge bonded wire construction. The sturdy build ensures the system withstands road conditions and prevents premature wear. It also includes a dust cap to keep the connector safe from dirt and grime, prolonging its lifespan.
Pulling a trailer with LED lights? No worries. This harness is designed to be fully compatible, ensuring your LED taillights function perfectly. With LED compatibility, your trailer's advanced lighting technology won’t face any interference or performance issues, giving you peace of mind regardless of your lighting setup.
Protect your connections with ease. The harness includes a dust cap for the connector and it is recommended to apply a small amount of grease on the electrical connections to prevent corrosion. This ensures your setup remains in top condition, even in harsh weather conditions, for long-lasting performance.
This custom-fit T-One connector plugs into your vehicle's wiring harness, which is located inside your trunk, 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 the 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 in an out-of-the-way location within your trunk.
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.
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.
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I'm very happy with this product. I installed it on a mk6 facelift Jetta S. It was really easy to install thanks to the brake light piggyback connectors supplied. The blade connector pigtail stows perfectly in the spare well underneath the cargo mat in the trunk, just pull it out when ready to use. I've used it towing a 5x8 cargo trailer cross country and a 12ft boat trailer. The set up works perfectly, is easy to install and well made... theres nothing not to like
Love how easy it was to install
Works as designed. Quite difficult and time consuming to install into VW Jetta, but when all is said & done, tested/works as it should.
We are a 74 year old couple. This install took us One hour and 35 minutes from the time I backed the car up on the ramps till I rolled it off. My wife did the pattern for cutting the slot and it was exact fit. IF you have some tools and a helpful partner this well planned out trailer kit is for you
I’m a very happy customer! Shipping was fast, install videos made it a breeze! Installed in less than 1hr. Product is also great, and it’s handling my jet ski just fine
Easy to install plug and play with no s plicing
Works good, easy install, overpriced for what it is tho.
The Video's helped a great deal! The hitch came in good condition however, I'd advise more wrapping around it because there was a 1" x 2" scratch that I touched up with paint.
Wiring went very well also. I pushed a pencil through and taped the wire on and pulled the wire through to hook it to the battery.
I saved a lot of money by doing it myself!
Thank You!
Very easy to do with only one person. Watched the video on both the hitch and wire installations and then went to work. Less then 2 hours all was done and worked perfect and looks even better. My complements to a well organized company who has the perfect teams
The wiring kit worked as expected, however there were a few issues. The instructions were not super clear on where to route the wiring. I was able to make it all work out, but if you aren't aware of good routing practices it may be bit hard to figure it out.
Also, the fact that the kit comes with a black wire for the positive lead you run to the positive terminal is pretty lame. If you get this kit, I recommend replacing that with a red wire, use some corrugated split loom to help protect the wires from chafing.
Gwendolyn Y.
9/18/2025
I'm sorry to hear that the install experience was not the best, especially with the instructions lacking. If you don't mind sharing, how did you end up routing the wires on your Jetta, Daniel?
Perfect, easy to install design
When I'm not hauling heavy and I still want 38MPG. Heaviest I have hauled yet is my Honda rincon 680.
Easily plugged into existing wire harnesses. Plenty of slack in the wires for good installation. The trailer lights work!
Jp
5/21/2021
Worked as expected every time I used it.
Works great
This review is a copy of the one I submitted for the trailer hitch kit but is totally applicable for the wiring harness kit
Well..... here it goes.
I'm not usually one to write reviews on ANYTHING, anytime, BUT I'm gonna make a exception this time concerning etrailer, aka, etrailer.com.
I priced purchase and installation of class one hitches at all of the local installer outlets (muffler shops, tariler rentals, etc.) and found that their markup on the parts alone was ridiculous plus their labor seemed a bit much as well. I then started researching online sites for trailer hitches and accessories from major manufacturers and suppliers.
I finally decided that price-wise, etc., I'd try etrailers.com and found their products, (the same used by the major installers), to be definitely as advertised.... perfect.
I checked w/ a buddy that has a small repair/ service biz and got his quote for a simple 'plug & play' hitch and wiring installation labor and was pleased, thus giving money to an independent mechanic known for his service vs. a big (screw ya over) company.
I called etrailer and spoke w/ a rep named Lisa and layed out my needs. She assured me that the parts that I was interested were in fact applicable and the kit would definitely be all inclusive. She followed up, via e-mail, after the fact, to be sure that all had gone well. I am now about to forward this review to her AND her superiors.
I am very pleased with everything about our deal, as was my mechanic. When I asked his opinion after he finished the installation, he nodded w/ a smile and said, "Nice, no probs, not even a missing scew." He added that in the future he would definitely suggest etrailer for customers wanting him to do installations.
Sooooooooo... Thank You Lisa! Well Done! Pat
After I installed hitch # C11410 on my 2012 Jetta TDI I proceeded to install this "easy" trailer wiring kit. The biggest challenge is wiring routing and only the black "hot" wire to the battery. The rest of kit with the T-Connectors works great and is not hard to access the taillight area. Once connected was able to hide the wiring under rear plastic trunk trim. I located the black box module to left side under side threshold panel. I routed the black wire through part of subframe via access plug in trunk to forward of axle and ran it between the long plastic shield under middle part of car along side the black fuel lines to just under forward firewall, then fished it up to the battery on left side. I used a piece of heat shrink on the splice between the fuse holder and black wire. I used a DMM to check the operation and seems to work properly. The instructions are not the best but adequate. Would recommend.
High quality product! Looks great on my 2015 VW Jetta TDI.
Installation was straight forward. I also got the light hookup harness. The trailer light kit wanted its own 12v power and ground. I opted to power it from the 12v outlet in the back seat area so I didn't have to run to the battery.
I don't usually do my own electrical work so I took it to my regular mechanic to install. It didn't cost a lot and the install was very clean, just like the videos show. The unit is hidden in the trunk and the wire comes out of the trim. It's been installed for a year and the trailer lights work every time I plug it in. Great product, works as advertised.
This harness was recommended by etrailer customer support and was well worth the few extra dollars. It just plugs in with no cutting or splicing of wires in just a few minutes. I did hire a mechanic to feed the wire through my chassis because I couldn't reach under my Jetta, but after that the installation was a breeze. Five stars to customer support.
The product is very likely not a bad product, but the installation is a pain in the rear end!!! Just trying to find a good place for the wire to exit the inside took more than an hour. Removed the rear seats, paneling, covering, etc. ... ended up taking out the aft portion of the left rear wheel well where there's a covered/plugged access point. Tie wrapped it onto the break lines all the way forward with about 20 or so ties, and then worked my way into the area where the battery is located. What a pain!!!
The manufacturer could do a much better job at giving more detailed instructions! A video like the one for the hitch installation would safe future customers a ton of time!
That's why this product is only getting a 3 star rating.
Very easy and clean install. I installed a 12volt cigarette lighter type plug on the 12 volt power lead, and can open rear center seat and plug into the outlet at the rear of the center console. When not using it, simply tuck it away.
Very easy install on this wire kit. The power wire to the battery is the only challenge. I ran mine up the drivers side along the trim by the carpet sills. The trim pieces pop off easily, and the rear seat also pops off with no required tools. There is a rubber boot for the main wire harness you can cut a small slit in behind the bettery where you can pass the wire from the cabin to the engine compartment. Not a bad job.
Pain to install the wire to the battery. I ran mine under the trim on the right side of the vehicle. I did not like how the video ran theirs on the left, and stated "stay as far away from the exhaust" while running their wire right next to the exhaust! Hypocritical... Also, the grommet on the right side of the vehicle is easier to remove and you don't have to destroy it for the installation, either. Finally, their lead wire should be longer and NOT black, black is conventional for negative and it seems contradictory to attach it to the positive lead on the battery. The poor quality electrical connector crimps seem like something very cheap and not suitable for a permanent installation. I would recommend not trying to save a few pennies by skimping on the electrical, after all this could lead to a vehicle fire! I used my own water-proof connectors. I also had to look for a metric bolt to fasten the electrical connection to the fuse box. I don't know why E-trailer cannot provide 1 simple nut with their kit to do this. Again, saving pennies in the wrong place and creating frustrated customers.
Great wiring harness it is built very well and of good quality components. Everything is included for the install. Very easy to connect into you existing wiring with the attached connectors and it is even easier after watching the etrailer install video. Thanks etrailer
Very nice wiring kit works well. Instructions are good and it does take some work to install. 4 stars because it comes with a very minimum amount of wires length where it becomes necessary to cut some corners. An extra 2 feet of run for the power wire would have been perfect.
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Karl C.
6/17/2014
Still Working Great! Thank you!!!