On board diagnostics Wikipedia. On board diagnostics OBD is an automotive term referring to a vehicles 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 1. 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. Tech 2 Scan Tool Saab' title='Tech 2 Scan Tool Saab' />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. Historyedit1. 96. A comparative list of functions and features for a large selection of aftermarket scan tools from 20 equipment manufacturers. GM-tech2-add-key-6.jpg' alt='Tech 2 Scan Tool Saab' title='Tech 2 Scan Tool Saab' />ALLDATA Debuts NextGeneration Technology that turns a tablet into a powerful scan tool SEMA 2017 Booth 10631, North Hall. HTB1TS7nbb3XS1JjSZFFq6AvupXaa/For-GM-TECH2-Scanner-Support-6-Softwares-for-GM-OPEL-SAAB-ISUZU-SUZUKI-HOLDEN-for-GM.jpg_640x640.jpg' alt='Tech 2 Scan Tool Saab' title='Tech 2 Scan Tool Saab' />Volkswagen introduces the first on board computer system with scanning capability, in their fuel injected. Type 3 models. 1. Datsun 2. 80. Z 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. 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 broadcasts at 1. Implemented on California vehicles for the 1. United States in 1. Most owners can read DTCs Diagnostic Trouble Codes by commanding the ECM Engine Control Module to flash the CEL Check Engine Lamp or MIL Malfunction Indicator Lamp on and off. A PC based Software package called Win. ALDL will listen to the CLCC Closed Loop Carburetor Control and early CLC EFI datastreams over a fairly easy to construct interface cable that converts the 1. TTL serial data being transmitted by the ECM to RS2. USB2 serial data but there is not much information transmitted by these early ECMs. An upgraded version of the ALDL protocol appears which communicates at 8. UART signaling. This protocol is defined in GM XDE 5. B. 1. 98. 8 The Society of Automotive Engineers SAE recommends a standardized diagnostic connector and set of diagnostic test signals. The California Air Resources Board CARB requires that all new vehicles sold in California in 1. 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. 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 1. CCR Title 1. 3 Section 1. CFR Part 8. 6 Section 8. The DTCs and connector suggested by the SAE are incorporated into this specification. The OBD II specification is made mandatory for all cars manufactured in the United States to be sold in the United States. The European Union makes EOBD mandatory for all gasoline petrol vehicles sold in the European Union, starting in MY2. European emission standards Directive 9. EC4. 2. 00. 3 The European Union makes EOBD mandatory for all diesel cars sold in the European Union. All cars sold in the United States are required to use the ISO 1. Controller Area Network CAN bus. Certain light vehicles in China are required by the Environmental Protection Administration Office to implement OBD standard GB1. July 1, 2. 00. 8. Some regional exemptions may apply. HDOBD heavy duty specification is made mandatory for selected commercial non passenger car engines sold in the United States. Standard interfaceseditGMs ALDL Assembly Line Diagnostic Link is a General Motors proprietary onboard diagnostic interface that started with the late 1. CLCC Closed Loop Carburetor Control and early GM EFI systems. Theres an appearance of standardization because the diagnostic jack didnt change over the years ALDL was utilized by GM. GM North America used a proprietary 1. Metripack 2. 80 diagnostic jack. Sheridan College Animation Program Reviews here. GM Australia Holden used a 6 position Metripack 2. The GM Europe Opel and Vauxall used a 1. Metripack 2. 80 diagnostic jack. ALDL was not a standard. It was actually extremely fragmented. The information exchange changed with each powertrain control module aka PCM, ECM, ECU. A PCM integrates transmission and engine control on one Processing unit. ECMECU are engine control only with a separate TCM Transmission Control Module if needed. While ALDL is the closest thing to standard onboard diagnostics prior to 1. ALDL was not a standard. ALDL was even fragmented within GM brands, models, and model years. Trim levels in the same model year, division, and nameplate can use different communications. Different versions presented differences in diagnostic jack pin outs, data protocols, and data rates this is the reason for the Mask files needed for aftermarket software communication. Earlier versions used 1. PCM or ECMTCM. 1. ALDL on 1. 99. 1 and later California emissions GM vehicles met the 1. California OBD I communication standard. This does not mean that ALDL is OBD I. OBD I was an early 1. California only mandate, not a United States federal mandate. It was not used on non California emissions vehicles. Some Asian, European, and North American diagnostic ports are sometimes incorrectly referred to as ALDL. A small number of vehicles manufactured before 1. GM Delphi Electronics engine and powertrain controllers however, these used a modified ALDL communication protocol. Most did not and there was not a homogeneous name for these other proprietary diagnostic protocols and interface ports. Ford EEC, Toyota DLC, Chrysler, Nissan, Volkswagen, and others used their own onboard Diagnostics protocols and connectors, and are also not OBD I compliant outside California. Multiplex OBD or M OBD is an OBD variant protocol used by Toyota, prior to OBD II compliance. Toyotas DLC3 Data Link Connector 3 is the standard 1. OBD II connector, but a proprietary cable and software is required as generic OBD II cables and software will not interface with it. The bus line is SIL Pin 71. A 1. 99. 1 and later California standard. It is not a USA Federal standard. The regulatory intent of OBD I was to encourage auto manufacturers to design reliable emission control systems that remain effective for the vehicles useful life. The Diagnostic Trouble Codes DTCs of OBD I vehicles can usually be found without an expensive scan tool. Each manufacturer used their own diagnostic link connector DLC, DLC location, DTC definitions, and procedure to read the DTCs from the vehicle. DTCs from OBD I cars are often read through the blinking patterns of the Check Engine Light CEL or Service Engine Soon SES light. By connecting certain pins of the diagnostic connector, the Check Engine light will blink out a two digit number that corresponds to a specific error condition. The DTCs of some OBD I cars are interpreted in different ways, however. Cadillac gasoline fuel injected vehicles are equipped with actual on board diagnostics, providing trouble codes, actuator tests and sensor data through the new digital Electronic Climate Control display. Holding down Off and Warmer for several seconds activates the diagnostic mode without the need for an external scan tool.