SAE international has released a new version of the J1939-73 diagnostics application layer. Besides some editorial improvements, some messages have been modified and added.
The updated document specifies the diagnostic messages (DMs), which provide the utility needed when the commercial vehicle is being repaired. DMs are also used during vehicle operation by the networked ECUs to report diagnostic information and self-compensate as appropriate based on information received. The document was first released in 1996. The new version contains some editorial improvements. This includes the strengthened wording around legacy requirements for DM1. DM3 and D11 response requirements have been revised. Other modified messages are DM7 and DM24, while DM1, DM2, DM12, DM13, DM19, and DM35 have been just clarified.
The SPN names in PGN layout have been updated to match actual SPN names. In general, parameter and message names have been aligned with the J1939 digital annex (DA) and the SAE J2403 specification. Other DTC reporting messages have been revised to follow the pattern of the recommended settings for unused bytes. The updated 193-pages document is part of the J1939 specification series and can be purchased from the SAE website.
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