To see if this custom-fit item will work for you please tell us what vehicle you'll use it with.
Wiring up a trailer doesn’t have to mean cutting into your vehicle’s factory wiring. The Curt T-Connector makes the job simple with plug-in connectors that match your tail light plugs. Just click them in place and you’ve got a working 4-flat trailer connection without touching a single factory wire. It’s clean, quick, and easy to do yourself.
This harness includes a powered converter that keeps the trailer lights running smoothly without drawing too much from the vehicle circuits. It delivers the correct power for running, brake, and turn signals through the 4-flat connector, giving you dependable lighting every time you tow.
The 4-flat connector covers the basics—running lights, brake lights, and turn signals—all in one simple plug. It’s the standard connection used for most small and mid-size trailers and makes this kit ideal for anyone adding towing capability for the first time.
Vehicles that don’t come with a tow package can still get full trailer lighting with this harness. The powered converter provides an independent power source so you can tow safely without relying on factory wiring. It’s a complete plug-and-lead setup ready to install right out of the box.

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 look at this Curt T Connector Vehicle Wiring Harness with four pole flat trailer connector. Now this wiring harness has been designed specifically for your 2014 and 2015 Cadillac CTS Sedan and then your 2016 to 2019 CTS Sedan with a CTS-V or excluding the CTS-V. Now in custom fit parts such as this harness, I do recommend taking advantage of our vehicle fit guide here at etrailer.com. Enter the year, make and model of your vehicle and our fit guide will confirm that this will work for you or if we have another harness that will work for you.
Now this harness is going to give you that four pole flat trailer connector at the back of your Cadillac to power the trailer signal lights. This is going to be compatible with five pole, six pole and seven pole adapters. Those adapters are of course sold separately. This does include a dust cap for that four pole flat connector. That cap is going to cover up those connection points when the plug is not in use.
Now this black box that you see here on this harness is a powered taillight converter. This is going to make sure that your vehicle's wiring matches out of your trailer. It does connect directly to your vehicle's battery to avoid overloading its electrical system, reducing strain on its wiring system. By the way, Curt does build each converter using surface mount technology for consistent reliable performance. It maximizes trailer light yield and intensity while producing minimal heat.
That's gonna make sure that you get superior operation in rough road conditions. Now this harness is designed to connect quickly and easily. You will need to locate your vehicle's wiring harness located in your trunk. To access those connection points, you will have to remove your rear scuff panel and some lining. But once you locate the connectors, you're gonna separate them and you wanna be careful not to break the locking tabs.
And then you're going to insert these T connectors in between those connectors in your vehicle. Now these T connectors are custom fitted for your Cadillac, so they're gonna match up perfectly with the connection points on your vehicle and they're gonna snap and lock together for a tight, secure fit. Once you have these 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. It does come with a self-tapping screw, so you can get this grounded to a suitable location such as your vehicle frame or cross member. You just wanna make sure that the surface is clean and rust free. Next, you will need to mount this converter box to a safe, out of the way location. You can do that with the double-sided adhesive tape that's included with this kit, or maybe even one of the many cable ties that's included with this kit. Then you will need to run the hot lead to your vehicle's battery in the trunk. And as you can see, this does already have a ring terminal attached to it and a fuse case here. It does come with a 10 amp fuse, so you'll just pop that into the fuse holder, close the cap to keep that fuse safe and protected. You will be able to secure any excess or slack in your wiring with the cable ties that's included with this kit. And once the installation is complete, you'll just stow your four-way connector in your trunk when it's not in use. Instructions are also included to guide you through that installation process. And it is also recommended that you use a small amount of dielectric grease on all of your electrical connections, like the plugs on the vehicle end and the four pole flat connector itself. That grease is designed to help prevent any electrical failures caused by corrosion and moisture. So on your screen, I am including our item number for that grease. You can just take that item number and pop it in the search field of our website. That will take you to that grease and you can add that to your order. Well, that's gonna wrap up our look today. I do hope that it was helpful for you. Again, my name is Andy. Thank you for joining me.
Ratings & Reviews
Easy to install once trunk lining is removed. Looks good.
Wiring was very easy to install. Instructions were very easy to follow and wire size was appropriate for this application. I highly recommend this product.
I hate giving it a 3 star rating but this is the second one I have purchased as the first one failed after only a couple of uses (I rarely pull anything with my Cadillac).
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