Trailer Wiring Harness Kit | etrailer Quickly and easily install a 4-way and 7-way trailer connector on your vehicle with this custom harness.T-connector plugs directly into OEM tow package wiring harness - no cutting or splicing vehicle's factory tow package wiring harness, which is located at the rear of your vehicle, slightly toward the driver's side installation is complete, the connectors will be stowed beneath your Amazon: trailer wiring kit 4 pin wwwon›Search›trailer wiring kit 4 pinAmazon: trailer wiring kit 4 pin. Skip to main content. ROSI 6ft 4 Wire 4-Flat Trailer Light Wiring Harness Kit 4 Way Trailer Wire Extension & Wishbone-Style with 20 Gauge White Ground Wire SAE J1128 Rated，with 4 Flat Connector for Under 80" Wide Trailers. $11 $ 11. 49.