T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
This item does not fit your vehicle
2009 Ford Flex
These items fit your vehicle
2009 Ford Flex
Arrives before Christmas To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.
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Installing a trailer wiring harness often feels like a daunting task, but the Tekonsha T-One Vehicle Wiring Harness with a 4-Pole Flat Trailer Connector makes it a breeze. Designed as a custom-fit for your vehicle, it plugs directly into existing wiring without the need for cutting, splicing, or tapping into your car's electrical system. Just locate the connection points in the rear cargo area, plug in the T-connector, connect the lead to your battery, and you're set. It's that simple!
Worried about overloading your vehicle’s electrical circuits? The integrated ModuLite power module in this T-One connector draws power directly from your car’s battery, ensuring your trailer’s lights are powered without straining your vehicle’s system. With the ModuLite, there’s virtually no draw on your vehicle's tail light circuits, delivering a worry-free connection every time.
Ever struggled with corroded connectors? The Tekonsha harness includes a dust cap for the 4-way flat connector to keep dirt and debris at bay. Plus, using a bit of grease on all electrical connections helps prevent corrosion, ensuring a reliable connection every time you hook up your trailer.
Whether you’re towing a small utility trailer or a larger setup, this connector is compatible with 5-pole, 6-pole, and 7-pole adapters (sold separately), making your towing setup versatile. This adaptability ensures you’re not restricted to a particular type of trailer, giving you the flexibility to tackle various towing tasks.
Constructed with 16-gauge bonded wire, this wiring harness is built to handle up to 5 amps for stop/turn lights and 7.5 amps for tail lights, offering reliable performance even in challenging conditions. Its robust build ensures it remains dependable and durable over time, providing peace of mind on every trip.
Perfectly designed for vehicles like the Mercedes GLC 300 models, this harness provides a hassle-free installation, assuming your car doesn’t have the Premium Package. It’s a favorite among those who want to maintain their vehicle's warranty without the need for cutting wires, making it a top choice for ease and reliability.
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I have a 2022 glc 300, and the wiring kit is not compatible. Thus kit is only for the models that don't use led lights.
Quick and easy install. With the rear fuse panel right there, it was an quick install. Everything you need is included in the package.
Keep up the good work. They come as expected and fast. Also good quality. You also have videos explaining each step which I think is great
After one year, the wiring harness looks and functions perfect. Nice quality wire and connectors.
It is hot and raining so I haven't installed my new trailer/car light kit. But, I have it out of the box, right off it didn't say China. The quality, fit, packing, spare parts and even the directions made more sense. This is designed in USA and made in Mexico. Looks to be a great product.
Fast shipping. Good prices. The wiring kit in the box with the hitch got beat up pretty bad, but appears functional. Hitch had some shipping scars also. Second or third hitch from you so I am a repeat customer.
Wrong harness supplied
Mike L.
11/9/2025
I see that you're already working with our customer service folks regarding your return. Please let me know if you need additional assistance!
Have not installed it yet, but it looks like good quality and exactly what I need. Wanted a wiring harness to add to GLC300 without splicing into the production wires.
Plan to update after install with how it went.
I purchased this product for my 2018 GLC 300.
It works really great and I highly recommend this product. It was super easy to connect the original harness no need to find what color for a signal.
The only thing that you have to figure out is the 12 volt to the battery connection. Lucky that Mercedes-Benz glc300 has the fuse box on the trunk so no need to run a cable all the way to the front.
This T-one harness from Tekonsha makes the installation easy without cutting any wires in the vehicle, will not void the vehicles warranty.
Pleased with the way the order was hand le.
It was installed by my local 4wheel parts store and has worked perfectly every since.
Good product. Install well. Work well.
Performance as indicated. No issues.
Still works great. Thanks!
They rock, super easy to work with
Great job
Good product i good service.
Do you have a question about this Custom Fit Vehicle Wiring?
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Mike L.
9/9/2025
Per Tekonsha (and our fitguide and the Tech Tip shown on the fitguide page) the harness won't work on vehicles equipped with the P03 Premium package. Is your GLC 300 equipped with that?