Body Wiring Harness - Discount Auto Body Parts Online Body Wiring Harness. Once the harness stops holding wires together, the wires are left just lying around your car's engine bay. The problem worsens when the rubber insulators covering each wire are cracked and worn through exposed metal wiring in the engine bay, the risk of shorted circuits and current arcing is increased. Body Wiring Harness - Wiring Harness | AutoPartsWarehouse The specialty body wiring harness, on the other hand, is used for vehicles with complex electrical systems, including factory amplifiers, special sound assemblies, and warning chimes. This harness comes with accessory power wires that can provide the required voltage for aftermarket electrical units.