Car wiring diagrams: Ford Trailer Harness Kit, wiring diagram, wire wiring harness, schematic circuit diagram, wiring diagran, wireing diagram, wirring diagram, wiring daigram, wiring diagrams. Ford Trailer Wiring Harness from JC Whitney. We offer a wide variety of Ford Trailer Wiring Harness to choose from and only include the best brands in the business..Find great deals on eBay for Trailer Wiring Harness in Towing Systems. Shop with confidence..Plug into existing taillight harness. No cutting or splicing. flat connector, gauge wire. Taillight converter included with kits when needed..