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SAE J1979

(R) E/E Diagnostic Test Modes

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Organization: SAE
Publication Date: 1 February 2017
Status: active
Page Count: 143
scope:

Introduction

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,

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.

Document Scope

This document supersedes SAE J1979 May 2007, and is technically equivalent to ISO 15031-5 2010, with the addition of new capabilities required by revised regulations from the California Air Resources Board and revised regulations from the European Commission.

This document is intended to satisfy the data reporting requirements of On-Board Diagnostic (OBD) regulations in the United States and Europe, and any other region that may adopt similar requirements in the future. This document specifies:

a. message formats for request and response messages,

b. timing requirements between request messages from external test equipment and response messages from vehicles, and between those messages and subsequent request messages,

c. behavior of both the vehicle and external test equipment if data is not available,

d. a set of diagnostic services, with corresponding content of request and response messages, to satisfy OBD regulations.

This document includes capabilities required to satisfy OBD requirements for multiple regions, model years, engine types, and vehicle types. Those regulations are not yet final for some regions, and are expected to change in the future. This document makes no attempt to interpret the regulations and does not include applicability of the included diagnostic services and data parameters for various vehicle applications. The user of this document is responsible to verify the applicability of each section of this document for a specific vehicle, engine, model year and region.

SAE J1979/ISO 15031-5 specifies diagnostic services and functionally addressed request/response messages required to be supported by motor vehicles and external test equipment for diagnostic purposes which pertain to motor vehicle emission-related data. Any external test equipment meeting the requirements of SAE J1978 is intended to be able to use these messages to retrieve emissions-related information from the vehicle.

Each section of this part of SAE J1979/ISO 15031-5 which specifies additional detail to existing sections of ISO 9141-2, ISO 14230-4, SAE J1850, and ISO 15765-4 supersede those specifications.

This part of SAE J1979/ISO 15031-5 references the SAE J1979-DA (Digital Annex), which includes all definitions of PIDs, OBDMIDs, TIDs and INFOTYPES.

NOTE: SAE J1979/ISO 15031-5 provides the mechanism to satisfy the requirements included in the country-specific regulations and not all capabilities included in this document are required by the country-specific regulations. SAE J1979 is not considered a final authority for interpretation of the regulations, so readers should determine the applicability of capabilities defined in this document for their specific needs.

Document History

SAE J1979
February 1, 2017
(R) E/E Diagnostic Test Modes
Introduction 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...
August 1, 2014
(R) E/E Diagnostic Test Modes
Introduction 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...
February 1, 2012
E/E Diagnostic Test Modes
Document Scope This document supersedes SAE J1979 May 2007, and is technically equivalent to ISO 15031-5 2010, with the addition of new capabilities required by revised regulations from the...
September 1, 2010
(R) E/E Diagnostic Test Modes
Document Scope This document supersedes SAE J1979 May 2007, and is technically equivalent to ISO 15031-5 2010, with the addition of new capabilities required by revised regulations from the...
May 1, 2007
(R) E/E Diagnostic Test Modes
Purpose This document supersedes SAE J1979 Apr 2002, and is technically equivalent to ISO 15031-5:2006, with the addition of new capabilities required by revised regulations from the California Air...
April 1, 2002
(R) E/E Diagnostic Test Modes Equivalent to ISO/DIS 15031-5:April 30, 2002
Purpose - This document supersedes SAE J1979 SEP1997, and is technically equivalent to ISO/DIS 15031-5:April 30, 2002. This SAE Recommended Practice is intended to satisfy the data reporting...
September 1, 1997
E/E Diagnostic Test Modes
This SAE Recommended Practice defines diagnostic test modes, and request and response messages, necessary to be supported by vehicle manufacturers and test tools to meet the requirements of the...
July 1, 1996
(R) E/E Diagnostic Test Modes, Recommended Practice
A description is not available for this item.
July 1, 1996
(R) E/E Diagnostic Test Modes
A description is not available for this item.
June 10, 1994
E/E DIAGNOSTIC TEST MODES
This SAE Recommended Practice defines diagnostic test modes, and request and response messages, necessary to be supported by vehicle manufacturers and test tools to meet the requirements of the...
December 1, 1991
E/E DIAGNOSTIC TEST MODES
This SAE Recommended Practice defines diagnostic test modes, and request and response messages, necessary to be supported by vehicle manufacturers and test tools to meet the requirements of the...

References

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