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Speedometer calibration?

Discussion in 'Gen 2 Prius Technical Discussion' started by Dummy, Jun 28, 2024 at 10:32 PM.

  1. Dummy

    Dummy Member

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    I’ve been considering a lift kit for the Prius for a while now. I got to wondering if I went with taller tires if it’s possible to re-calibrate the speedometer so it would be accurate. Possible?
     
  2. mr_guy_mann

    mr_guy_mann Senior Member

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    You would have to talk to someone who does a lot of work on the Combination Meter. The ABS system takes readings from the wheel speed sensors and sends a Vehicle Speed Sensor reading out on the data network. The CM receives the VSS data and displays it as a number on the speedometer.

    You could reach out to someplace like TexasHybridBatteries.com and find out if they can do anything like changing how the speedo displays the VSS data.

    Posted via the PriusChat mobile app.
     
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  3. Tombukt2

    Tombukt2 Senior Member

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    I mean how much big of a tire are you going and how high are you going I'm 40 mm and could only get a 27-in tire I would be almost wheel well liner to wheel well liner and all that so then that has to come out now I have no wheel well liners or I go up higher so are you going high enough to get 35-in tires on so your tires are about 12-in taller 14-in taller than the 25 or so outer diameter of the factory because I'll just looked at with a tape measure a couple of times so don't quote the exact numbers so in reality the 10 or 12 in taller that you are now what does that really do to this speedometer mathematically throws you off what 6 miles an hour hell even 10 as long as you know what you're driving I can't even see the relativity of getting that adjusted outer whatever you'd call that like my motorcycles are inaccurate but I know what the inaccuracy is I can even rip the speedometer apart and pick the needle up off the post and move it over and guys do that stuff I mean for what I'm not really understanding because I'm worried I might get a ticket?.
     
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    I doubt it. Ditto for the odometer. Hacking either is possibly illegal, the odometer in particular.
     
  5. Dummy

    Dummy Member

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    The recommended tire size from the lift kit manufacturer is one inch larger diameter than the factory Prius tires, it’s a small lift. The reason I want to lift it is to stop rubbing on large speed bumps and the dips where parking lots join streets. It would also make it easier for some of my older relatives to get in and out of the car easier as the seat would be almost two inches higher than it is now.
     
  6. Dummy

    Dummy Member

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    I doubt that it’s illegal. In the past I have changed differential gear ratios on trucks that were still under warranty and the dealer sold me the proper transmission speed sensor gear to make the speedometer correct again. I just don’t know how the Prius speed sensor works.
     
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  7. Tombukt2

    Tombukt2 Senior Member

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    I lifted mine 40 mm I still have the stock tire size on it I'm getting ready to go to 215 65 15 that's about 2 in or 1.7 in past or over the stock outer diameter for the car I'm not expecting any real drastics speedometer changes I can't wait to see right now I have none I'm just up and on the same factory 185 65 15s.
     
  8. Tombukt2

    Tombukt2 Senior Member

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    I lifted the car to make getting in and out easier and when I told my trailer the trailer sits more level