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Wiring a trailer doesn’t have to mean splicing into factory wires. This Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector plugs directly into your vehicle’s existing wiring. No cutting, no tapping—just a quick plug-in connection that keeps the factory wiring intact and working like it should.
The included 4-flat trailer connector gives you the standard lighting functions you need for towing—running lights, brake lights, and turn signals. It’s an easy way to power your trailer lights and stay safe and visible every time you hook up.
Getting the harness inside the vehicle is simple. You can route the power wire through an existing firewall grommet or under the vehicle using the grommet near the spare tire compartment. That means no drilling or messy routing—just a clean, factory-style finish.
If your vehicle didn’t come with trailer wiring, this harness has you covered. The built-in converter handles the signal translation needed for trailer lights, so it works even if your vehicle doesn’t have a tow package. It’s a straightforward way to get reliable trailer lighting without extra adapters or custom wiring work.

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Speaker 1: Today we're taking a look at the Curt T-connector vehicle wiring harness with a four-pull flat trailer connector. This product fits certain years and models of the Toyota Yaris. To ensure that this is a fit for your vehicle, you can use the vehicle fit guide located at etrailer.com.This unit, once installed, provides a four-way flat connector at the back of your vehicle to power your trailer's signal lights. It is compatible with five-pull, six-pull, and seven-pull adapters. Adapters are sold separately. And it comes with a dust cap for the four-way flat connector.
That way you can cover up the connection points when the plug's not being used.All the wire on the unit runs to this black box. This is the included tail light converter. This ensures that your vehicle's wiring matches that of your trailer's the powered module connects directly to the vehicle battery through the wiring to avoid overloading the vehicle's electrical system.The unit's constructed using surface mount technology for consistent, reliable performance. What that does is it maximizes the trailer light yield and intensity while producing minimal heat and ensures superior operation, even in rough road conditions.The unit is designed to connect quickly and easily. All you need to do is locate the connection points in the rear cargo area and plug in your T-connectors.
These are custom fit for your vehicle, so they're going to match up perfectly with the ports on the vehicle, and they snap lock together for a nice, tight, secure fit.Once you have those plugged in, you will need to make a ground connection. Your ground wire is the white wire with the ring terminal attached to it. You want to get that grounded to a suitable grounding location, and you can use the included grounding screw to do that if needed.Then you'll need to mount the converter box to a safe, out-of-the-way location, and you can do that with the cable ties. You can also use the double-sided adhesive foam tape provided with the kit.Next, you'll run the hot lead to the vehicle battery. That's the short black wire coming out of the box.
This gets connected to one end of the bundle with one of the included butt connectors. The other end of the bundle runs to the vehicle battery, gets another butt connector attached to it, and gets connected to one half of the fuse holder. The other half of the fuse holder gets a ring terminal attached to it and gets connected to the positive post of the vehicle battery. It does come with your 10-amp fuse, goes directly into the fuse holder, and it's got the cap that goes over to keep it safe and protected.Once you have that done, you can secure any excess or slack in the wiring with the included cable ties. Once your installation's complete, the four-way connector will be stowed in an out-of-the-way location within your rear cargo area.
Plenty of wiring here, so you can extend it out the back when you need to use it, roll it up, tuck it away when you don't.It is recommended that you use a small amount of dielectric grease in all of your electrical connections, like the plugs on the vehicle and the 4-port connector itself. That grease is specifically designed to prevent corrosion to the connection points. It's sold separately and available at etrailer.com.When it comes to the maximum amperage for the stop and turn lights, we're looking at 3 amps per circuit, and the for tail lights we're looking at 6 amps per circuit.That's going to do it for today's look at the Curt T-connector vehicle wiring harness.
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