Trailer Wiring Diagrams | etrailer Trailer Wiring Diagrams. Trailer One has flat pins, which are often referred to as blades. The other has round pins. The round pin style is very rare. The RV style 7-way with flat pins (or blades) is very common. It is often found on newer trucks and SUVs that come equipped from the factory with a trailer hitch. 7-Way Round TrailerNissan Rogue · Best Accessories · Jeep Wrangler Unlimited · Honda CR-V · Ford F-250 Super Duty 7 Pin Hitch Wiring Diagram | Free Wiring Diagram Assortment of 7 pin hitch wiring diagram. A wiring diagram is a streamlined standard pictorial depiction of an electric circuit. It shows the elements of the circuit as streamlined shapes, as well as the power and signal links in between the devices. Wiring diagrams for 7 pin 12N 'N' type trailer lights Wiring diagrams for 7 pin 12N 'N' type trailer lights plugs and sockets. 7 pin 12N wiring diagram. This is slowly being replaced by the European 13 pin plug and will become less popular as the reverse light is introduced to new trailers between now and 2012 when it will be legal requirement.