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OBD-II PIDs (On-board diagnostics Parameter IDs) are codes used to request data from a vehicle, used as a diagnostic tool.. SAE standard J1979 defines many OBD-II PIDs. All on-road vehicles and trucks sold in North America are required to support a subset of these codes, primarily for state mandated emissions inspections.
A PC-based OBD analysis tool that converts the OBD-II signals to serial data (USB or serial port) standard to PCs or Macs. The software then decodes the received data to a visual display. Many popular interfaces are based on the ELM327 or STN [41] OBD Interpreter ICs, both of which read all five generic OBD-II protocols. Some adapters now use ...
The data link connector (DLC) is the multi-pin diagnostic connection port for automobiles, trucks, and motorcycles used to interface a scan tool with the control modules of a given vehicle and access on-board diagnostics and live data streams. [1] Prior to 1996, many OBD-I data link connector's were in the engine compartment, usually near the ...
The ELM327 is a programmed microcontroller produced for translating the on-board diagnostics (OBD) interface found in most modern cars. The ELM327 command protocol is one of the most popular PC-to-OBD interface standards and is also implemented by other vendors.
When a DTC is raised by the ECU it stores a freeze frame of data (eg rpm). This is often helpful when trying to figure out what caused the problem (eg maybe it raises a DTC for misfire but only when rpm is higher than 5000, which indicates maybe a weak coil). "Freeze DTC" merely indicates which DTC triggered the freeze frame data to be stored.
SAE J1939 defines five layers in the seven-layer OSI network model, and this includes the Controller Area Network (CAN) ISO 11898 specification (using only the 29-bit/"extended" identifier) for the physical and data-link layers. Under J1939/11 and J1939/15, the data rate is specified as 250 kbit/s, with J1939/14 specifying 500 kbit/s.
Transport-layer services include the transmission of multi-CAN-frame messages based on the ISO 15765-2 multi-frame messaging scheme. It was developed and is used primarily by General Motors for in-vehicle communication and diagnostics. [3] GM's Tech2 uses the CANdi (Controller Area Network diagnostic interface) adapter to communicate over GMLAN.
When the computer detected a fault, it illuminated the MIL. Up until OBDII, on most cars the MIL could output codes. When two pins on the ALDL are jumped, the light would flash the codes, for instance (blink) (pause) (blink) (blink) for code 12. Some manufacturers, such as Honda, retained this feature even after OBDII.