AHD J1939 On-Vehicle Data Connectors Amphenol Sine Systems AHD J1939 On-Vehicle Data Connectors are industry-standard connectors designed for vehicle diagnostic and data communication in various harsh-environment uses. The AHD J1939 connectors feature a higher-layer protocol based on a Controller Area Network (CAN). These Amphenol Sine Systems on-vehicle data connectors are used widely in the diesel engine industry and provide diagnostic data. This diagnostic information includes vehicle engine speed, temperature, oil temperature, and exhaust emissions.