Ground Strap (Earth Strap)

Every electrical circuit needs a return path; in cars this is the body and engine, linked by ground straps. Engines sit on rubber mounts, so without a strap they would be electrically isolated from the body. There are usually several ground points around the engine bay and inside the car.

Current from the battery positive flows through each consumer and returns to the battery negative through the metal body and ground straps.

A corroded or broken ground strap can cause slow cranking, dim lights, strange gauge readings, sensor faults and even damage to throttle cables. A voltage drop test between the battery negative and the engine block quickly shows a poor ground.