(This SAE Recommended Practice combines, revises, and replaces two previous recommended practices: SAE J555a and SAE J556.) This SAE recommended Practice covers the application of primary wiring distribution system harnesses to automotive, truck, and similar type vehicles. This is written principally for new vehicles but is also applicable to rewiring and service. It covers the areas of performance, operating integrity, efficiency, economy, uniformity, facility of manufacturing, and service. This practice applies to wiring systems of less than 50 V.