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Thread: Mode 22 help?

  1. #1
    Join Date
    Sep 2010
    Madison, WI

    Mode 22 help?

    I am new to this forum and writing my own ELM based digital dash. I have things setup to individually read values from the ECU (mode 1), but would like to extend to features I suspect are in Mode 22. I have an ECU from a 2000 vette in a vehicle I can test with, and another from a 2002 GM on the bench. What I am looking for is the standard stuff to flow near real-time if possible from the ECU (RPM, Speed) and the other stuff (Water Temp, Oil Press, Volts) could actually be polled. Is there a way to have the ECU just send me these values? I've seen a couple of posts that indicate that is possible provided you send keep alive packets every once in a while.

    Any pointers to documentation on this would be greatly appreciated. This is just a hobby for me, planning on putting a digital dash in my '65 GTO that I am currently restoring.

    Thanks in advance for any help/pointers.

  2. #2
    VENDOR - ScanTool Vitaliy's Avatar
    Join Date
    Dec 2006
    Phoenix, AZ
    What is the problem with requesting the data that you need, as opposed to coercing the ECU to periodically push this data to you?
    OBDLink MX: world's smallest, fastest, most advanced OBD/Bluetooth adapter with SW and MS CAN support. Read the review to learn more.
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  3. #3
    Join Date
    Sep 2010
    Madison, WI
    No real problem asking for the data each time, just thought there might be a more efficient way to do this. The RPM and Speed are the ones that i was hoping I could just tell the ECU I wanted on a stream basis.

    Is this the way most of the scanner products work, send each command and display the results? I was just thinking that this was a lot of two-way data on the serial bus. But, if that is the way it's generally done, makes what I want to do fairly straightforward.

  4. #4
    Low Bitrate
    Join Date
    Jul 2005
    With GM.. most of the mode $01 pids translate into mode $22 pids.. So if you want PID $0C, you can use mode $22 PID $000C.. (just add a preceding $00).

    The rest of the PIDs are enhanced stuff and proprietary. You can purchase them through a trade organization called ETI ( But it is very expensive.. and those who get the data are not allowed to share it.. (of course).

    Good luck.
    Hack your car's CAN BUS at

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