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Thread: Get Current Gear with ODB II

  1. #1
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    Get Current Gear with ODB II

    Hi all,
    i just started interacting using OBDII protocol with my car (RAV4) through a VB program i did.

    I managed to find out the standard PIDs such as RPM, Speed etc but i have not managed to find anything related to current speed.

    After some googling, i was pointed to the PID 19F5 but with no information on what mode it should be used.

    Does anyone have any idea of how to get the current gear ?

    Thanks in advance
    Chris

  2. #2
    Variable Bitrate
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    Current Speed: Pid 0D Current gear is not available, only manufacturer specific.
    http://en.wikipedia.org/wiki/OBD-II_PIDs

  3. #3
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    Thanks for the link,
    the info i found and it made me think its standard is this one

    http://obdproject.com/OBD2Info/Specs/pidlist.htm

    May be i should talk to the author.

  4. #4
    Variable Bitrate
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    That's what I call an old and incomplete list. Even back in 1996 we started out with more standard pids than $1C. Any pids with 4-digit number is non-standard and manufacturer specific.

  5. #5
    North of the land of Hey Huns
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    You could use speed and rpm to figure out what gear you're in. It would be fairly easy with a standard transmission. A bit tougher with an auto... but not entirely impossible.
    "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
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  6. #6
    Constant Bitrate firstorbit84's Avatar
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    ^^^ Ya that's exactly what I was thinking. It'd be easier if you knew the gear ratios and final drive.

  7. #7
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    Thanks for the comments,
    as a final question can anyone let me know the formula that relates speed , rpm and gear ratio ?

  8. #8
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    Quote Originally Posted by chrisstavrou View Post
    Thanks for the comments,
    as a final question can anyone let me know the formula that relates speed , rpm and gear ratio ?
    I'm not sure that's going to work. The rpm can change depending upon engine load (up hill, down hill, pulling a heavy load) while the gear and speed remain the same. Probably get a general idea, but it's not going to be accurate under every circumstance. Besides, I thought the whole point of an automatic transmission was so you didn't have to worry about the gears?

    VegasGuy

  9. #9
    SuperMod - OBDII GPS Logger forum
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    Spend a few minutes logging data, rpm and vss, in each gear. Draw out a chart of rpm/vss. The height at the long flat bits are the gear ratios. Write down those numbers.

    Now go back and while you're driving, pick the rpm/vss ratio that's closest to your known gear. Done.

    Of course, doing this automatically is a fair bit harder. My current plan is to [when I have time] do the ratios, use FFTs to throw away the high frequency stuff, and calculate the flat bits.

    Gary (-;
    OBDGPSLogger, for logging OBDII and/or GPS data
    OBDSim, an OBDII/ELM327 software simulator
    mp3car forums: obdgpslogger, obdsim

  10. #10
    VENDOR - ScanTool Vitaliy's Avatar
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    And they say people never use higher math in everyday life. Way to go Gary.
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