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Scangauge Xgauge for Inverter Coolant Temp in Centigrade?

Discussion in 'Gen 3 Prius Technical Discussion' started by GreenJuice, Nov 19, 2011.

  1. GreenJuice

    GreenJuice Active Member

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    Can anyone help with the Xgauge code for the Gen 3 inverter coolant temperature to be displayed in Centigrade/Celsius?

    I'm based in the UK and planning on some aggressive grill blocking as temperatures start to fall. Thought I should be keeping an eye on this.

    Thanks in anticipation
     
  2. jdcollins5

    jdcollins5 Senior Member

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    Here is a spreasheet of Gen III XGauges put together by PC member Adrian Black. It includes the XGauge you are looking for.

    The inverter coolant data in the spreadsheet is in F. If you will change the MTH to 000100010000 this should give you C.
     

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  3. F8L

    F8L Protecting Habitat & AG Lands

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    Jd, do you know the code for inverter temp for the GenII? I can only seem to find the battery temp.
     
  4. vincent1449p

    vincent1449p Active Member

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    That would be 40ºC too high.:confused:

    The MTH in ºF is 00090005FFD8. Let x = value read by SGII, so the equation is:

    F = 9 / 5 * x - 40

    But C = 5 / 9 * ( F - 32 )

    C = 5 / 9 * (( 9 / 5 * x - 40 ) - 32 )

    C = 5 / 9 * ( 9 / 5 * x - 72 )

    C = x - 40

    Therefore, the MTH should be 00010001FFD8.

    Vincent
     
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  5. vincent1449p

    vincent1449p Active Member

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    Hi F8L,

    What is your SGII firmware version? If it is 4.0x and higher, you can try these Xgauges.

    Vincent
     
  6. jdcollins5

    jdcollins5 Senior Member

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    Vincent,

    Yes, you explained this to me some time back. I keep forgetting about the 40 offset.

    Thanks for setting me straight again.

    Dwight
     
  7. F8L

    F8L Protecting Habitat & AG Lands

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    I forgot which version I have but it is at least a few years old. I'll check to see if I have that version or newer. Thanks! :)
     
  8. GreenJuice

    GreenJuice Active Member

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    Thanks guys!

    I wonder if the offset value is somehow linked to the convergence point of the Centigrade and Fahrenheit scales (-40 C = -40 F).

    I think I'm beginning to see how your MTH code offset is applied. I'm guessing that it is something to do with FFD8 (Hex) being equal to 65496 (Decimal) and FFFF (Hex) being equal to 65535 (Decimal), a difference of 39 in decimal. Therefore going backwards from 0000, FFD8 gives a value that is 40 less than zero....?

    Do you have 'Idiot's guide' to how MTH codes are constructed for someone with a little basic maths understanding? It would be helpful for applying scale conversions like US to Imperial (as we like to call it - can't forget the days of the empire!).
     
  9. vincent1449p

    vincent1449p Active Member

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    I don't think it is related. I've seen offset of -50 and other values. The value of the offset will determine what the minimum value it wants to measure.

    It uses two's complement system. FFD8 is -40 in decimal.

    I started to learn Xgauge programming from this guide. It is very brief and a lot of stuffs I 've to figure out by trials and errors.

    Vincent
     
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  10. GreenJuice

    GreenJuice Active Member

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    Wow that is brief! You have done an amazing job to have started from there! :hail: