SAE J1939-73 defines the SAE J1939 messages to accomplish diagnostic services and identifies the diagnostic connector to be used for the vehicle service tool interface. Diagnostic messages (DMs) provide the utility needed when the vehicle is being repaired. Diagnostic messages are also used during vehicle operation by the networked electronic control modules to allow them to report diagnostic information and self-compensate as appropriate, based on information received. Diagnostic messages include services such as periodically broadcasting active diagnostic trouble codes, identifying operator diagnostic lamp status, reading or clearing diagnostic trouble codes, reading or writing control module memory, providing a security function, stopping/starting message broadcasts, reporting diagnostic readiness, monitoring engine parametric data, etc. California-, EPA-, or EU-regulated OBD requirements are satisfied with a subset of the specified connector and the defined messages.
The document has been updated to reflect additional regulatory requirement as listed below.
HD OBD “NOx Bin Tracking” and “GHG Tracking”
Greenhouse Gas (GHG) Tracking Specific to Hybrids
HD ZEP CCR 1956.8
Diagnostic Message DM59 (Continuous-MI Time While Engine Operating, Time Elapsed Since DTCs Were Erased)
Updated SPN 1220 for new regulation entries
Included in: On-Board Diagnostics for Light and Medium Duty Vehicles Subscription Learn More
On-board diagnostics (OBD)
Variable valve timing
Diesel / compression ignition engines
Exhaust gas recirculation (EGR)
Diesel particulate filters
Engine cooling systems
Also known as: SAE J 1939/73
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