This SAE Standard encompasses connectors that form the electrical interface(s) between the heavy duty lighting device(s) and the truck and truck/trailer wiring harness system. This document provides design and performance requirements based upon the mechanical, electrical and environmental conditions and covers applications of connectors for direct current electrical systems of 24 V nominal or less in heavy-duty signaling and marking devices. This standard excludes forward lighting devices (i.e., fog lamps) but includes the following list of lamps: