Boat trailer lights are easy to understand and change.
WIRE HARNESS 5 WAY - Boat Trailer Parts
Amazon.com: Trailer Wiring Harness Kit 4-Way Wishbone Style, Y Style 18AWG Pure Copper Core Color Coded Wire with Standard 4-pin Flat Plug Connector, 4' Female and 25' Male for 12V Trailer Boat
Trailer Wiring 101
T-H Marine 4-way 25' Trailer Wiring Harness in the Trailer Parts & Accessories department at Lowes.com
Amazon.com: MaxxHaul 4-Pin Flat Trailer Wiring Harness Kit 25' Male and 4' Female [18 Gauge Color Coded Wires] for Utility & Boat Trailer Wire Kits Blue : Automotive
25 Ft Marine Grade Boat Trailer "Y" Wishbone Tinned Copper Wiring Harness Set - White's Marine
Bass Pro Shops Trailer Wire Harness 4-Way | Bass Pro Shops