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Hooking up trailer lights doesn’t need to be complicated. The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector plugs directly into the vehicle’s existing tail light wiring. There’s no cutting or splicing—just pop the connectors in behind each tail light and you’re ready to go. The built-in converter handles the signal transfer for running lights, turn signals, and brake lights so everything works right from the start.
The harness connects behind the tail lights using factory-style plugs, keeping the install hidden and tidy. Once connected, you can route the 4-flat wire out through the trunk or a rear panel when towing, then tuck it away when you’re not. It gives you a clean setup that’s ready when you need it without extra loose wiring hanging around.
A solid ground is key to good trailer lighting, and this harness makes that easy. The white ground wire comes with a ring terminal to mount directly to bare metal on the frame. When grounded properly, it keeps your running, turn, and brake lights consistent without flickering or weak signals.
The 4-pole flat connector provides power for running lights, turn signals, and brake lights—the standard setup for small and midsize trailers. It’s ready to pair with accessories like a 7-way adapter if you decide to add a brake controller or need a charging circuit later on.
The included dust cover keeps dirt and water out of the connector when it’s not in use. It helps prevent corrosion so your trailer lighting stays reliable season after season. When it’s time to tow, just remove the cap, plug in the trailer, and hit the road knowing your wiring is ready to work.

Customer Satisfaction Score:
96% were satisfied with this product
4% of customers were not satisfied
Ratings & Reviews

Frederick
2/20/2026
Great works everytime. No issuse at all


Michael G.
9/16/2015
Weve had our Curt hitch for over a year now and it still looks like new. Were very satisfied and recommend Curt and Etrailer.

Jeff
5/17/2015
Thanks so much.

Jd
6/18/2016
I use the hitch mostly for my bicycle rack and it works as designed with no problems.I have tested the wiring harness and it operates the lights on my boat trailer also with no problems.Im happy with the products.

Joseph
6/7/2018
Works perfect still. Pulled my little 5x8 trailer all over Texas. Its worked out really well.

Robert B.
8/12/2020
Zero trouble with wiring. Had to wire brush rust from receiver once. Good Wisconsin rust never sleeps. Generally the whole package is so perfect that you forget its even there till you go to tow something.
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Tim W.
7/27/2018
I havent had to pull any more trailers, but I have no doubt it will work just fine, the next time I need to unroll it from the spare tire well!