To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.
Wiring a trailer doesn’t have to mean cutting into factory wires. The Curt T-Connector plugs directly into the vehicle’s existing wiring to create a clean, 4-flat trailer connection. It’s designed as a hidden, plug-in harness that keeps the install simple and the wiring protected.
Once connected, you get a standard 4-pole flat trailer connector that powers your trailer’s running lights, turn signals, and brake lights. It’s all built into one plug-and-lead setup made for reliable signal transfer every time you hook up.
Vehicles without a factory tow package or those using sensitive wiring systems benefit from the powered converter built into this harness. It draws power directly from the battery rather than the vehicle’s lighting circuits, protecting onboard electronics and ensuring consistent trailer lighting performance.
The harness tucks neatly out of sight and uses existing trim paths for a clean finish. Once installed, only the 4-flat connector is visible when you’re ready to tow, keeping everything else protected from road grime and weather.

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Hi, everybody, Andy here with etrailer.com. Let's take a real quick look at this CURT T-Connector Vehicle Wiring Harness with 4-pole flat trailer connector. Now, this wiring harness has been designed to fit your 2024 and newer Buick Envista, and on custom-fit parts such as this harness, I do recommend taking advantage of our Vehicle Fit Guide here at etrailer.com. Simply input the year, make, and model of your vehicle and our Fit Guide will confirm if this will work for you or if we have something comparable that will work for you. Now, this harness is going to give you that 4-pole flat trailer connector at the back of your Buick to power your trailer signal lights. This will also be compatible with five, six, and 7-pole adapters.
Those adapters are sold separately, and this black box that you see here is a powered taillight converter. This is going to ensure that your vehicle's wiring matches out of your trailer. It will connect directly to your vehicle's battery to avoid overloading its electrical system, reducing strain on its wiring system, and CURT builds each converter using surface-mount technology for consistent, reliable performance that's gonna help maximize trailer light yield and intensity while producing minimal heat and ensuring superior operation, even in rough road conditions. Now, this harness is designed to connect quickly and easily. You will need to locate your vehicle's wiring harness, which is located behind the driver's side and passenger's side bumper, and you will probably have to remove the floor coverings and the driver's side taillights to access that harness, but once you locate the connectors, you wanna separate them, and you wanna be careful not to break the locking tabs, and then you're going to insert these T-connector ends between the vehicle's wiring, the wiring connectors rather, and then lock them into place.
These T-connectors are custom-fitted for your vehicle, so they're gonna match up perfectly to the connection points on your vehicle, so they're gonna snap and lock together for a tight, secure fit. Now, once you have these connectors plugged in, you will need to make a good ground connection. The ground wire is this white wire, and as you can see, it does have a ring terminal attached to it, and it does come with a self-tapping screw that you can see right there, and so you're gonna be able to get this grounded to a suitable location, such as your vehicle's frame or crossmember. You just wanna make sure that the surface is clean and rust-free, then you do wanna mount the converter box to a safe, out-of-the-way location. You can do that with another mounting screw that you might have on hand in your garage, or you can use the double-sided adhesive tape that's included with this and you can definitely use that, but I would imagine that this would come loose over time, maybe especially due to heat, so you could also use one of the cable ties here to help secure that or some other way.
You just wanna make sure that that's going to be mounted securely. And then you will need to run the hot lead to the vehicle's battery, and that's going to be this black wire that's coming out of the converter box. This short black wire is going to get connected to one end of this included bundle of black wire using one of the included butt connectors, and then you're going to route the other end of this black wire to your vehicle's battery. And once you have the other end of this bundle routed to the vehicle's battery, you're going to take this fuse holder along with the second butt connector and you're gonna take one of those wires with the butt connector and connect it to the routed end of this bundle of black wire, and then you're gonna take that ring terminal and attach to the other end of this fuse holder, and then that ring terminal will get it attached to your vehicle's positive post battery, and then this does include a 10-amp fuse. You'll pop that fuse into the fuse holder, it has a cap there to keep that fuse safe and protected.
Again, I mentioned the cable ties. You can use that to secure any slack in your wiring, and not all wiring harnesses come with this, but I noticed that this does come with a small tube of black silicone so if you have to make any punctures or cuts in gaskets, you can use that black silicone to fill in that hole or fill up that crack to help maintain that water resistance, so that is included with this. Now, once installation is complete, your 4-way connector can be stowed in an out-of-the-way location in your cargo area. Instructions are included to guide you through that installation process, and then I also wanted to recommend some dielectric grease. Dielectric grease is recommended on all of your electrical connections, like your plugs and the 4-way connector itself. That grease is designed to help prevent electrical failures caused by corrosion and moisture. So, on your screen, I am including the model number for that grease. You can just take that model number, pop it in the search field of our website. That will take you to the grease, and you can add that to your order. Well, I think that's gonna wrap up our quick look today. I do hope that it was helpful for you. Again, my name is Andy, thank you for joining me.
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