How to Install Trailer Wiring | Color Coded Diagrams If your vehicle is not equipped with a working trailer wiring harness, there are a number of different solutions to provide the perfect fit for your specific vehicle. Complete with trailer wiring color code diagrams, this guide walks through each available trailer wiring installation solution, including custom wiring, splice-in wiring and replacement wiring. Tow Wiring Harness - RV Upgrade Store Get the best deal from RV upgrade online store for Tow Wiring Harness. We offer a variety of Tow Wiring Harnesses at an affordable price. Visit our store TODAY.