7 Pin Trailer Wiring Harness | etrailer Install a 7-way, RV-style trailer connector on your vehicle with this easy-to-splice harnessLite draws power directly from the battery to avoid overloading your vehicle's circuits. Brake electrical system Includes harness with 4-pin connection point for plugging in a brake controller wiring adapter (sold separately) Supplies required fuses, wire taps, and additional hardware Constructed Amazon: 7 pin wiring harness ANTO 4 Wire Flat to 7 Way RV Trailer Light Custom Plug Wire Harness Electrical Converter Adapter. 4.6 out of 5 stars 12. $16 $ 16. 99. Get it as soon as Fri, Jul 19. 7-Pin Wiring Harness with Junction Box - 7 Blade Wire Cable for Truck Camper RV - Weatherproof and Corrosion Resistant Breakaway Kit - 10 FT. 3.4 out of 5 stars 4.