for single byte headers J2178-4 – Defines standards for network messages with three byte headers* J2284-3 – Defines 500K CAN physical and data link layer J2411 – Describes the GMLAN (Single-Wire CAN) protocol, used in newer GM vehicles. Often accessible on the OBD connector as PIN 1 on newer GM vehicles. SAE standards documents on HD (Heavy Duty) OBD J1939 – Defines a data protocol for heavy duty commercial vehicles ISO standards ISO 9141: Road vehicles – Diagnostic systems. International Organization for Standardization, 1989. Part 1: Requirements for interchange of digital information Part 2: CARB requirements for interchange of digital information Part 3: Verification of the communication between vehicle and OBD II scan tool ISO 11898: Road vehicles – Controller area network (CAN). International Organization for Standardization, 2003. Part 1: Data link layer and physical signalling Part 2: High-speed medium access unit Part 3: Low-speed, fault-tolerant, medium-dependent interface Part 4: Time-triggered communication ISO 14230: Road vehicles – Diagnostic systems – Keyword Protocol 2000, International Organization for Standardization, 1999. Part 1: Physical layer Part 2: Data link layer Part 3: Application layer Part 4: Requirements for emission-related systems ISO 15031: Communication between vehicle and external equipment for emissions-related diagnostics, International Organization for Standardization, 2010. Part 1: General information and use case definition Part 2: Guidance on terms, definitions, abbreviations and acronyms Part 3: Diagnostic connector and related electrical circuits, specification and use Part 4: External test equipment Part 5: Emissions-related diagnostic services Part 6: Diagnostic trouble code definitions Part 7: Data link security ISO 15765: Road vehicles – Diagnostics on Controller Area Networks (CAN). International Organization for Standardization, 2004. Part 1: General information Part 2: Network layer services ISO 15765-2 Part 3: Implementation of unified diagnostic services (UDS on CAN) Part 4: Requirements for emissions-related systems Security issues Researchers at the University of Washington and University of California examined the security around OBD, and found that they were able to gain control over many vehicle components via the interface. Furthermore, they were able to upload new firmware into the engine control units. Their conclusion is that vehicle embedded systems are not designed with security in mind. There have been reports of thieves using specialist OBD reprogramming devices to enable them to steal cars without the use of a key. The primary causes of this vulnerability lie in the tendency for vehicle manufacturers to extend the bus for purposes other than those