Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
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2004 Volvo S40
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2004 Volvo S40
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Wiring a trailer doesn’t have to mean cutting into factory wires. The Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector plugs directly into the existing tail light wiring. It’s a hidden, plug-and-lead style setup that keeps the install clean and avoids splicing or taping connections. Once in place, the harness provides a standard 4-flat connection ready for your trailer lights.
Many factory tail light circuits can’t handle extra trailer load, so this harness includes a powered converter that draws 12-volt power straight from the battery through an included 12-gauge wire. That design protects the vehicle’s wiring while giving the trailer full brightness for running, turn, and brake lights. A fuse is added in line for protection and reliable operation.
The converter is built to manage typical trailer lighting draw—3 amps per stop/turn circuit and 6 amps per tail light circuit. That’s plenty of power for standard trailers, and it supports either incandescent or LED lights without damaging sensitive electronics. It’s a dependable way to power every light on your trailer without overloading your vehicle circuits.
Once installed, the 4-pole flat trailer connector gives you all the basics—running lights, turn signals, and brake lights—right where you need them at the hitch. It’s a simple, weather-resistant connection that works with common trailers and adapters when you need to tow different setups.
Customer Satisfaction Score:
96% were satisfied with this product
4% of customers were not satisfied
Ratings & Reviews
Robert L.
11/15/2016
Great. Went on a five month trip up the California-Oregon coast. No problems with wiring ??
Gregg H.
6/9/2017
works great! I use it 2 or 3 times per week.
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Kevin
4/20/2026
Still working perfectly.