PID A4 - Transmission Actual Gear

Hello all (especially the nerds),

can someone help me out how to use the Service ID 0x01, PID 0xA4?
The Wiki only says the following:
4 bytes
1st is 0xA0 - unsupported, 0xA1 - supported.
2nd ?!?
3rd & 4th *1000 should give you the ratio.

Tried to emulate that with several different ELM327-Apps, but never got a meaningful result.

If someone might just send out 01 A4 and post the response on two or three different gears, that would be amazing!
My car does not support it...
And as a bonus, I´m sure that these findings will help to add the current gear to RaceChrono as well ;)

Best regards and many thanks in advance!


  • Maybe I was able to answer this to myself.
    But not in total, so I just describe what I found out.

    Another Source (an open source SAE J1699 tester) does it like that:
    Byte1 describes with value & 0x00 unsupported, 0x01 gear supported and 0x02 ratio supported.
    Byte2 contains the gear, but 4 bit shifted.
    Byte3 & Byte4 are the ratio like described above.

    Tested that with another app (Car Scanner) and it didn´t work.
    So why the bitshifting?
    This can only mean two values combined into one! Tested it that way
    0x01, Neutral
    0x11, 1. Gear
    0x21, 2. Gear
    0x31, 3. Gear

    And it worked! I´m still unsure if the app or tester is wrong, but I´ll leave them a comment and maybe can proove it.
  • Which car or bike supports this? None of my vehicles does unfortunately.
  • All of my bikes have the current gear available, but as you know, by their very own (none OBD) implementation...
    Cars mostly had the gear information somewhere in their transmission control units, depending on the manufacturer.
    Since 2019 it was officially announced into OBD2 SAE J1699 - 2020 on PID A4.

    So I guess not many cars have it already, but they will have it in the future!

    My translation from my Suzuki ECU to OBD II now works with some different apps and I will create a custom PID on RaceChrono to proove it also works!
    Should be something like A>>4.

    PS: I´ll mail you my source of equations, maybe this will help you out for future PID´s.
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