Trailer Wiring Diagrams | etrailer Mounting Your Trailer Wiring Harness Often the 4-pole trailer connector will remain in the trunk or cargo area of a car or SUV when not in use. This helps to extend the life of the connector by protecting it from the elements and accidental damage. When it is needed for towing, simply pull the connector out and shut the trunk or rear door. Roadmaster Universal Hy-Power Diode Wiring Kit - e trailer Recommended Flat Towing Wiring Harness for 2000 Jeep Wrangler Towed Behind Motorhome I'd recommend the Hopkins flat towing wiring harness, part # HM56202. The harness is a plug and play installation, with no cutting or splicing required.