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J1939 specifications

Revisions and updates

The SAE J1939 committee meets quarterly and reviews the different parts. The Digital Annex, the compliance test, and the marine diagnostics specifications have been released in new versions.

J1939 documents are periodically reviewed and updated (Photo: CiA)

The SAE J1939 committee holds four meetings per year, in which the J1939 documents are reviewed and updated in several task forces. Most important are the updates on PGs (parameter group) and SPs (suspect parameter). In October, the J1939DS digital annex has been released. It covers parameters approved in the August meeting. The recently published J1939/84 update improves the January 2016 version by improving Table A1 for non-OBD modules that provide battery voltage and Component ID. Table A1 ADDS parameters that are required of 2016MY engines has been improved. An informative message classification is added for certain warning messages that are of general interest. Non-OBD responses for commonly reused SPNs among non-OBD modules will no longer receive warning messages when provided by non-OBD modules. Four key destination specific queries in section 6 were changed to allow a retry with failure, to better assure that key data used in criteria and other tests would be captured. The purpose of this Recommended Practice is to verify that vehicles and/or devices are capable of communicating a required set of information, in accordance with the diagnostic messages specified in SAE J1939-73.

The J1939/5 document describes the application of the SAE J1939 recommended practices for compliance with on-board diagnostic malfunction detection system requirements for marine sterndrive and inboard spark ignition engines, as mandated by the California Air Resources Board (CARB). These Otto-cycle engines are not derived from automotive diesel-cycle engines. The revised version published recently supports now the J1939/14 physical layer (500 kbit/s data rate). It recognizes recent changes in J1939/73.

The J1939 committee discusses also the migration to CAN FD and specifies a functional safety protocol to be used for transmitting safely PGs and the mapped SPs. Another important work item is the recommended practice for hybrid heavy-duty vehicles.


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