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Thread: Tundra speedometer calibration

  1. #1
    Potential Tuner
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    May 2019
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    Tundra speedometer calibration

    Im needing some help with speedo calibration there are 2 boxes for tire radius, 2 boxes for transfer case and 2 boxes for rear gear. Are the values supposed to be the same in each box? Or is this a before and current scenario? The description is less than helpful. i have tried changing the values and speedometr still reads 8-9 mph too slow. Please help

    upload_2019-4-16_22-5-40.jpg
    Last edited by rbosley2; 06-04-2019 at 09:12 PM.

  2. #2
    Tuner in Training
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    May 2016
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    The Tacoma only has one set of boxes, but I have adjusted them to match my new tires without any effect on the speedometer itself.. I have not yet scanned the OBD to see what the ECM is reporting (because I am lazy), but I suspect the ECM has its own internal speed reading that is separate from the speedometer cluster.

    Can anyone shed some light on this?

  3. #3
    Pretty much all Toyota's take the speedo cluster input direct from the ABS controller which calculates the speed from the wheel sensors. This signal is then passed on to the PCM which calculates it own vehicle speed for OBD2 and other things. Automatic vehicles will also calculate a backup vehicle speed value which is used in some transmission calculations. Most manufacturers make a complete mess of vehicle speed inputs and calculations, it seems Toyota is no exception... This means that changing these gear/tire values will not result in a change of the speedo cluster.
    I count sheep in hex...

  4. #4
    Tuner in Training
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    May 2016
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    Good to know.. I don't suppose there's anything on the horizon allowing us to reprogram either the ABS controller or the instrument cluster itself to apply a correction factor? I know hypertech sells an inline speedometer calibrator but I'm having trouble justifying $220 on top of wheels and tires...

  5. #5
    Quote Originally Posted by njedwardz View Post
    Good to know.. I don't suppose there's anything on the horizon allowing us to reprogram either the ABS controller or the instrument cluster itself to apply a correction factor? I know hypertech sells an inline speedometer calibrator but I'm having trouble justifying $220 on top of wheels and tires...
    No plans at this time sorry
    I count sheep in hex...