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 Amazon: 7 pin wiring harness. Skip to main content. Try Prime All CURT 58180 Trailer-Side 7-Way Round Trailer Wiring Harness Socket with Spring, 7-Pin Trailer Wiring. 4.8 out of 5 stars 17. $10 $ 10. 39. Get it as soon as Mon, Jul 22. FREE Shipping on orders over $25 shipped by Amazon.