SAE J1978-1_202312

SAE J1978-1 specifies a complementary set of functions to be provided by an OBD-II scan tool. These functions provide complete, efficient, and safe access to all regulated OBD (on-board diagnostic) services on any vehicle which complies to SAE J1978-1 The SAE J1978-1 content of this document is intended to satisfy the requirements of an OBD-II scan tool as required by current U.S. on-board diagnostic (OBD) regulations. This document specifies: A means of establishing communications between an OBD-equipped vehicle and an OBD-II scan tool. A set of diagnostic services to be provided by an OBD-II scan tool in order to exercise the services defined in SAE J1979 and SAE J1979-2. The presentation of the SAE J1978 document family, where SAE J1978-1 covers first generation protocol functionality defined in SAE J1979, and SAE J1978-2 covers second generation protocol functionality defined in SAE J1979-2. The SAE J1978 document family does not preclude the inclusion of additional capabilities or functions in an OBD-II scan tool. However, it is the responsibility of the OBD-II scan tool designer to ensure that no such capability or function can adversely affect either an OBD-equipped vehicle, which may be connected to the OBD-II scan tool, or to the OBD-II scan tool itself. Differences in the SAE J1978-1 requirements are highlighted by bold italic text in the technical requirements sections of this document. This SAE Recommended Practice supersedes SAE J1978 May 2022. This document, SAE J1978-1, reflects a task force decision to embark on a family-of-documents approach for SAE J1978 OBD-II Scan ool. SAE J1978-1 content has been generated with content from SAE J1978, technical reference to SAE J1979, and regulation requirements. The evolution of the SAE J1978 family of documents is illustrated in Figure 1. Note: SAE J1978 will become stabilized at the same time SAE J1978-1 reaches publication date milestone. Changes that have been made to related SAE documents (e.g., SAE J1979) will also affect the content of this document, requiring changes herein. For reference, the evolution of the SAE J1979 family of documents is illustrated in Figure 2.