7 Pin To 6 Pin Wiring | etrailer Hopkins Trailer Connector Adapter - 7-Pole Round Pin to 6-Pole. This adapter plugs quickly and easily into your 7 -way, round- pin, vehicle-end connector to convert it for use with a 6 -way round, trailer-end connector. How to Wire a 6-Pin to 7-Pin Trailer | It Still Runs How to Wire a 6-Pin to 7-Pin Trailer. Go to a hardware store and select an adapter that joins the two different types of wiring harnesses. Slide the 6-pin side of the adapter into the vehicle's harness by pushing the two together. Slide the 7-pin side of the adapter in the trailer's harness. Test that the trailer's lights respond to the vehicle's systems as appropriate.