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Speedometer way off. Failure problem help

Discussion in 'Gen 2 Prius Technical Discussion' started by Rjhdog, Dec 22, 2011.

  1. Rjhdog

    Rjhdog Junior Member

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    Hello all,
    I know of the slight 4%-10% mph difference commonly discussed here but this morning I noticed a huge discrepency. Speedometer showing 115 mph when Traveling 65 -70 mph on highway. Also showing 50mph while going 30 or so.
    Tire size is stock.
    Just noticed it today.
    Its an 04 Prius with approx 130k miles.
    Questions:
    Is it safe to drive it or is this a sign of a larger failure to come?
    Is it a DIY fix?
    Figured at least to disconnect battery to see if it helps, good idea?

    Any advice appreciated.
    Many thanks. RJ
     
    #1 Rjhdog, Dec 22, 2011
  2. fuzzy1

    fuzzy1 Senior Member

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    Did you accidentally hit the button that converts the display to kilometers per hour?
     
    #2 fuzzy1, Dec 22, 2011
    1 person likes this.
  3. saechaka

    saechaka Member

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    On most Pri it's about 2mph off. What's the formula to convert from mph to km?
     
    #3 saechaka, Dec 22, 2011
  4. fotomoto

    fotomoto Senior Member

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    1.6 conversion so 1 mile equals 1.6 km. 70mph is approx 113kmph so yup that 115 figure you saw was most likely kmph. 30mph=48kmph
     
    #4 fotomoto, Dec 22, 2011
  5. uart

    uart Senior Member

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    Yep, definitely km/h.

    50 km/hr = 31 MPH

    115 km/h = 71 MPH
     
    #5 uart, Dec 22, 2011
  6. Pinksand

    Pinksand New Member

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    OH, that is probably what I did yesterday when I washed the car. How do I turn it back to MPH instead of KPH? I am not in front of my dash, where is the button located to turn it back to MPH???

    Thx!
     
    #6 Pinksand, Apr 16, 2012
  7. jdenenberg

    jdenenberg EE Professor

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    I remember the button being at the bottom right of the MFD.

    JeffD
     
    #7 jdenenberg, Apr 16, 2012
  8. cwerdna

    cwerdna Senior Member

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    Look near the hazard light button.
     
    #8 cwerdna, Apr 16, 2012
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