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Thread: How does OBDII protocol works?

  1. #1
    Newbie
    Join Date
    May 2011
    Posts
    7

    How does OBDII protocol works?

    Hi,
    I'm trying to understand how the OBDII protocol works.
    If I connect an OBDII dongle, how does it collects the data?
    Does it only listen on the bus and collect the data as it passes? or does it send a data-request and gets an answer?

    What else can I send to the engines computer other than MIL light reset? anyone knows a list or something?

    Thanks!

  2. #2
    Variable Bitrate
    Join Date
    Oct 2008
    Posts
    376
    You need a combination of Hardware and Software. The hardware is a cable between the diagnostic connector and the device that runs the software for reading codes and/or data. It doesn't matter whether you use a PC-program or a dedicated scanner.
    OBDII provides ways for reading/clearing codes and reading all kinds of data - live data, test results and ecu information.
    The way it works is the scanner will ask a question and the OBDII legislated ecu's (engine and automatic gearbox) will answer.

    Have a look here: http://www.mp3car.com/engine-managem...is-obd-ii.html
    and here: http://en.wikipedia.org/wiki/OBD-II_PIDs

  3. #3
    Newbie
    Join Date
    May 2011
    Posts
    7
    Thanks alot!

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