Trailer Wiring Harness Kit: Amazon Anyway, the installation was pretty straight forward and took about 1.5 hours to fish the new wiring harness with the help of the old one. I soldered and used heat shrink tubing to connect the rear taillights. Routing the Power Wire for a Trailer Wiring Harness Some trailer wiring harness 4-Way and 7-Way connectors require a power wire to be routed from the harness to the vehicle battery. The power wire is required on trailer wiring harnesses for some vehicles because the electrical system on those vehicles cannot handle the amperage draw associated with trailer lights.
Related with straight to wire trailer wiring harness truck