Routing the Power Wire for a Trailer Wiring Harness 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 Power Harness-73039G01 - Wiring - Battery & Chargers - E-Z-GO 6 Gauge Battery Cables; Battery Wiring Harness; Hour Meters. Hour Meter Kits; Hour Meter Wiring Harness & Bracket; Home; E-Z-GO ; Battery & Chargers; Wiring; Power Harness-73039G01; In stock. Power Harness-73039G01. $157. Part Number. 73039G01. This item is eligible for Free Shipping. Qty. Add to Cart View Fitment.