A CURT custom wiring harness (also called a T-connector) is a simple, plug-and-play electrical device that eliminates the need for cutting, splicing and soldering when installing vehicle-to-trailer wiring. Most vehicles do not come ready to tow. Unless your vehicle has a towing package, it is probably not equipped with a trailer wiring connector. This is where CURT's custom wiring harnesses come into play. Custom wiring harnesses plug into your vehicle's electrical system using original equipment (OEM) connectors. Our custom wiring harnesses use two or more OEM connectors to plug in at the taillight assembly and provide a standard trailer socket to allow a trailer to be plugged into your vehicle's power system. This harness provides a 4-way flat connector socket and comes with a circuit-protected converter. It is designed to be a custom wiring harness for certain years of the Ram ProMaster (to verify your vehicle compatibility, see the CURT application guide at curtmfg.com). CURT custom wiring harnesses are long-lasting and quick to install. They come with dust covers to keep your connector clean when not in use and feature a one-year limited warranty to give you peace of mind.