The specification for this link is as defined by GM's Emissions Control System Project Center document XDE-5024B. It reports real-time sensor data, component overrides, and Diagnostic Trouble Codes. The protocol communicates at 160 baud with Pulse-width modulation (PWM) signaling and monitors all engine management functions. Included in this system is a proprietary 5-pin ALDL that interfaces with the Engine Control Module (ECM) to initiate a diagnostic request and provide a serial data stream. 1981: General Motors introduces its 'Computer Command Control' system on all US passenger vehicles for model year 1981.

Diagnostic Trouble Codes (DTC's) are displayed through the electronic climate control system's digital readout when in diagnostic mode. 1980: General Motors introduces the first data link on their 1980 Cadillac Eldorado and Seville models.These systems are also analog in nature, though some provide rudimentary diagnostic capability through factory tools, such as the Kent Moore J-25400, compatible with the Datsun 280Z, and the Cadillac Seville. 1975: Bosch and Bendix EFI systems are adopted by major automotive manufacturers in an effort to improve tail pipe emissions.This system is entirely analog with no diagnostic capabilities. 1968: Volkswagen introduces the first on-board computer system, in their fuel-injected Type 3 models.You can help by converting this section, if appropriate. This section is in list format but may read better as prose. 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 a person to rapidly identify and remedy malfunctions within the vehicle. Early versions of OBD would simply illuminate a malfunction indicator light (MIL) or ' idiot light' if a problem was detected, but would not provide any information as to the nature of the problem. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of on-board vehicle computers. OBD systems give the vehicle owner or repair technician access to the status of the various vehicle sub-systems. On-board diagnostics ( OBD) is a term referring to a vehicle's self-diagnostic and reporting capability. Used to connect to the SAE J1962 Data Link Connector (DLC) found in many cars of the era.

Various angles and details of a 'MaxScan OE509' - a fairly typical onboard diagnostics (OBD) handheld scanner from the first decade of the 21st century.

Nissan scan data 1 phone adapter