SAE J1979 / ISO 15031-5 set includes the communication between the vehicle's OBD systems and test equipment implemented across vehicles within the scope of the legislated emissions-related OBD.
To achieve this, it is based on the Open Systems Interconnection (OSI) Basic Reference Model in accordance with ISO/IEC 7498-1 and ISO/IEC 10731, which structures communication systems into seven layers. When mapped on this model, the services specified are broken into:
—
Diagnostic services (layer 7), specified in:
—
ISO 15031-5/SAE J1979 (emissions-related OBD),
—
ISO 27145-3 (WWH-OBD),
—
Presentation layer (layer 6), specified in:
—
ISO 15031-2, SAE J1930-DA,
—
ISO 15031-5, SAE J1979-DA,
—
ISO 15031-6, SAE J2012-DA,
—
ISO 27145-2, SAE J2012-DA,
—
Session layer services (layer 5), specified in:
—
ISO 14229-2 supports ISO 15765-4 DoCAN and ISO 14230-4 DoK-Line protocols,
—
ISO 14229-2 is not applicable to the SAE J1850 and ISO 9141-2 protocols,
—
Transport layer services (layer 4), specified in:
—
DoCAN: ISO 15765-2 Transport protocol and network layer services,
—
SAE J1850: ISO 15031-5/SAE J1979 Emissions-related diagnostic services,
—
ISO 9141-2: ISO 15031-5/SAE J1979 Emissions-related diagnostic services,
—
DoK-Line: ISO 14230-4, ISO 15031-5/SAE J1979 Emissions-related diagnostic services,
—
Network layer services (layer 3), specified in:
—
DoCAN: ISO 15765-2 Transport protocol and network layer services,
—
SAE J1850: ISO 15031-5/SAE J1979 Emissions-related diagnostic services,
—
ISO 9141-2: ISO 15031-5/SAE J1979 Emissions-related diagnostic services,
—
DoK-Line: ISO 14230-4, ISO 15031-5/SAE J1979 Emissions-related diagnostic services,
—
Data link layer (layer 2), specified in:
—
DoCAN: ISO 15765-4, ISO 11898-1, -2,
—
SAE J1850,
—
ISO 9141-2,
—
DoK-Line: ISO 14230-2,
—
Physical layer (layer 1), specified in:
—
DoCAN: ISO 15765-4, ISO 11898-1, -2,
—
SAE J1850,
—
ISO 9141-2,
—
DoK-Line: ISO 14230-1,
in accordance with Table 1
SAE document reference concept
ISO 15031 references several SAE documents which contain all terms, data and DTC definitions.
See Figure 1 - SAE Digital Annex document reference with the following definition of content in ISO 15031 parts:
—
SAE J1930: the document is concerned with a procedure for naming objects and systems and with the set of words from which names are built. It references SAE J1930-DA which contains all standardized naming objects, terms and abbreviations.
—
SAE J1979: the document is concerned with the definition of emissions-related diagnostic services (diagnostic test modes). It references SAE J1979-DA which contains all standardized data items like PIDs, Test Ids, Monitor IDs and InfoType IDs.
—
SAE J2012: the document is concerned with the procedure for defining emissions-related diagnostic trouble codes. It references SAE J2012-DA which contains all standardized data items like DTCs and FTBs.
On-Board Diagnostic (OBD) regulations require passenger cars, and light, medium and heavy duty trucks, to support a minimum set of diagnostic information to external (off-board) “generic” test equipment.
SAE J1979-DA (Digital Annex)
This part of ISO 15031 references the SAE J1979-DA. The SAE J1979-DA is concerned with the definition of:
—
Parameter Identifiers (PIDs),
—
Test Identifiers (TIDs),
—
OBD Monitor Identifiers (OBDMIDs),
—
Unit and Scaling Identifiers (UASIDs), and
—
Info Types (INFOTYPEs);
SAE Digital Annex revision procedure
New emissions-related regulatory requirements drive new in-vehicle technology to lower emissions. New technology related OBD monitor data and diagnostic trouble codes need to be standardized to support the external (off-board) “generic” test equipment. All relevant information is proposed by the automotive industry represented by members of the appropriate SAE task force.
ISO 15031-5/SAE J1979 references a "Change Request Form" to be used for new data items to be defined by the SAE task force for standardization. The standardized data items will be defined in the SAE J1979-DA. Once the information has been balloted and approved, the documents will be published on the SAE Store Web Site.
The revision request form and instructions for updating ISO 15031 Part 5 / SAE J1979 can be obtained on the Registration Authority's web site at:
The column titled "Resources" shows a document with the title: J1979-DA_Revision_Request_Form.doc. Double click on the name and you will be asked to download the document with the filename:
SAE_J1979-DA_Revision_Request_Form.doc
Fill out the revision request form with your request.
Please send e-mail with completed revision request form as attachment to:
Rationale:
SAE J1979 is being republished with no appendices to complement the J1979DA document that is now avalailable. No other changes have been made since the last publication. The rationale from the previous publication has been retained below for reference.
Changes have been made to this document in order to keep pace with changes made to the California Air Resources Board legislation: Title 13, California Code Regulations, Section 1968.2, Malfunction and Diagnostic System Requirements for 2004 and Subsequent Model-Year Passenger Cars, Light-Duty Trucks, and Medium-Duty Vehicles and Engines (OBD II), and Regulation (EC) No 715/2007 of the European Parliament and of the Council of June 20, 2007 on type approval of motor vehicles with respect to emissions from light passenger and commercial vehicles (Euro 5 and Euro 6) and on access to vehicle repair and maintenance information as amended by Commission Regulation (EC) 692/2008.
Some clarifications and functional enhancements have also been included in this document.
Included in: On-Board Diagnostics for Light and Medium Duty Vehicles Subscription Learn More
Related Topics:
Electronic control units
Spark ignition engines
Diesel / compression ignition engines
On-board diagnostics (OBD)
Emissions control
Electronic control systems
Control systems
Also known as: SAE J 1979
Save money while getting up-to-date access to the standards you need! Subscribe to the SAE J1939 Standards Collection on the Web and get one year of anytime access and automatic updates to the J1939 family of documents, plus all cross-referenced and selected related documents.
SAE MOBILUS
Subscribers can view annotate, and download all of SAE's content.
Learn More »
