This V-belt transmits rotational force from the engine crankshaft pulley to the alternator rotor. It sits in the accessory drive loop, maintaining tension to keep the alternator charging the electrical system at the required output. A worn or glazed belt slips under load, causing the alternator to undercharge and the battery warning lamp to illuminate. The belt has four ribs on its inner face, matching the pulley grooves for positive engagement. As an original-manufacturer component, it is molded to the same cross-section and length as the belt fitted during production, so no adjustment of the tensioner beyond its normal range is needed.