Timing constraints (e.g., how many milliseconds an ECU has to respond to a DM14 request before a timeout occurs).
The standard is the "Application Layer for Diagnostics" within the broader J1939 protocol suite. It defines how heavy-duty vehicles—such as trucks, buses, and tractors—report faults, perform repairs, and maintain emissions compliance. Core Functions of SAE J1939-73 Sae J1939-73 Pdf
: Initiating self-tests and commanding specific actuator behaviors. Timing constraints (e
Because J1939 is built on CAN, it utilizes 29-bit identifiers. Diagnostic messages use specific Parameter Group Numbers (PGNs). For example: 65226 (0xFECA) DM2 PGN: 65227 (0xFECB) Handling Multi-Packet Messages Timing constraints (e.g.