What Is the Purpose of an Electrical Wiring Harness in an Automobile?

An automotive wiring harness lies at the heart of the car’s electrical system and allows mechanics and automotive designers to connect all of the wiring for parts under the hood to a central area. This provides excellent organization and makes it easier to follow wiring diagrams to troubleshoot problems and replace wiring or fix faulty connections.

The wiring harness connects to the primary fuse box, or all fuse boxes on some models, under the hood. The fuse box takes power from the battery, which is in turn charged by the alternator, and protects the wires in the harness against surges that could damage sensitive components. The wiring harness provides a series of connections that allow experienced mechanics and vehicle owners to narrow down problems to specific systems and electrical connections, making it easier to work on the vehicle’s electronics.

Components commonly connected to the wiring harness include the on-board diagnostic computer and fuel-injection system of many vehicles, auxiliary lights and dashboard controls. The emissions system and similar electrical components also connect directly to the harness, as do turn signals and other required systems. On many automobile wiring harnesses, the connectors and wires that connect these systems swap out easily for quick repairs and replacement.