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On-board diagnostics (OBD) is an automotive term referring to a vehicle's self-diagnostic and reporting capability. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle subsystems. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of on-board vehicle computers. Early versions of OBD would simply illuminate a malfunction indicator light or "idiot light" if a problem was detected but would not provide any information as to the nature of the problem. Modern OBD implementations use a standardized digital communications port to provide real-time data in addition to a standardized series of diagnostic trouble codes, or DTCs, which allow one to rapidly identify and remedy malfunctions within the vehicle. ==History== * 1968: Volkswagen introduces the first on-board computer system with scanning capability, in their fuel-injected Type 3 models. * 1975: Datsun 280Z On-board computers begin appearing on consumer vehicles, largely motivated by their need for real-time tuning of fuel injection systems. Simple OBD implementations appear, though there is no standardization in what is monitored or how it is reported. * 1980: General Motors implements a proprietary interface and protocol for testing of the Engine Control Module (ECM) on the vehicle assembly line. The 'assembly line diagnostic link' (ALDL) protocol communicates at 160 bit/s Implemented on California vehicles for the 1980 model year, and the rest of the United States in 1981. The only available function for the owner is "Blinky Codes" that transmit the Diagnostic Trouble Code (DTC) with the blinking pattern of the "Check Engine" (MIL) light. * 1986: An upgraded version of the ALDL protocol appears which communicates at 8192 bit/s with half-duplex UART signaling. This protocol is defined in GM XDE-5024B. * 1988: The Society of Automotive Engineers (SAE) recommends a standardized diagnostic connector and set of diagnostic test signals. * 1991:〔http://www.arb.ca.gov/msprog/obdprog/obdfaq.htm〕 The California Air Resources Board (CARB) requires that all new vehicles sold in California in 1991 and newer vehicles have some basic OBD capability. These requirements are generally referred to as "OBD-I", though this name is not applied until the introduction of OBD-II. The data link connector and its position are not standardized, nor is the data protocol. * ~1994: Motivated by a desire for a statewide emissions testing program, the CARB issues the OBD-II specification and mandates that it be adopted for all cars sold in California starting in model year 1996 (see CCR Title 13 Section 1968.1 and 40 CFR Part 86 Section 86.094). The DTCs and connector suggested by the SAE are incorporated into this specification. * 1996: The OBD-II specification is made mandatory for all cars manufactured in the United States to be sold in the United States. * 2001: The European Union makes EOBD mandatory for all gasoline (petrol) vehicles sold in the European Union, starting in MY2001 (see European emission standards Directive 98/69/EC〔http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1998L0069:19981228:EN:PDF〕). * 2003: The European Union makes EOBD mandatory for all diesel vehicles sold in the European Union * 2008: All cars sold in the United States are required to use the ISO 15765-4〔http://www.iso.org/iso/catalogue_detail?csnumber=33619〕 signaling standard (a variant of the Controller Area Network (CAN) bus).〔http://www.epa.gov/fedrgstr/EPA-AIR/2005/December/Day-20/a23669.htm, U.S. EPA regulations requiring ISO-15676 CAN standard to be supported for all U.S. sold cars model year 2008 and later.〕 * 2008: Certain light vehicles in China are required by the Environmental Protection Administration Office to implement OBD (standard GB18352〔http://english.mep.gov.cn/inventory/Catalogue_Standards/200807/t20080718_125885.htm〕) by July 1, 2008.〔http://baike.baidu.com/view/171354.htm, Chinese news article on implementation of OBD (Google translation http://translate.google.com/translate?hl=en&sl=zh&tl=en&u=http://baike.baidu.com/view/171354.htm)〕 Some regional exemptions may apply. * 2010: HDOBD (heavy duty) specification is made mandatory for selected commercial (non-passenger car) engines sold in the United States. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「On-board diagnostics」の詳細全文を読む スポンサード リンク
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