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Tire Pressure missing in vehicle status display

Discussion in 'Model S' started by Abqnative, Jun 16, 2017.

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  1. Abqnative

    Abqnative Member

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    IMG_0592.JPG I am a new MS owner and Trying out various features. While the owners manual is useful, it seems to miss some areas or I am in the wrong section. The display shows "--" where I expect a PSI number. Is there a first step that I am missing? The "reset pressure" option is greyed out.
    Thanks
     
  2. msnow

    msnow Active Member

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    You need to drive it around for a few minutes to get a reading.
     
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  3. Silverstreak

    Silverstreak Member

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    Step on the brake and start it
     
  4. drklain

    drklain Member

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    The TPMS (Tire Pressure Monitoring System) sensors are low power units inside the tires. They only transmit once every couple of minutes. Generally takes having the car on and driving for about 3-5 minutes before all the numbers will populate on the screen (note this is not unique to Tesla but every TPMS-equipped car I've ever owned).
     
  5. SabrToothSqrl

    SabrToothSqrl Active Member

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    Go for a drive.
     
  6. Silverstreak

    Silverstreak Member

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    My Porsche worked as soon as it was turned on, just sayin.
     
  7. drklain

    drklain Member

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    Quite possible...but I've never owned a Porsche. The various cars/minivans we've owned that had tire pressure readouts in the car all started out blank and generally took a few minutes to get all 4 numbers to appear (1 would appear, then the next, etc. until all appeared). I assumed this was due to some polling periodicity.

    I wonder if the Porsche was really reading them all instantly or just displaying the last readings the tires had/last update while the cars I've owned obviously dropped the readings from memory when the car was turned off? I'm sure there are people more knowledgeable than me on this list who know exactly how the system works.
     
  8. SabrToothSqrl

    SabrToothSqrl Active Member

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    Last Known Value. It would be displayed until a value replaced it, or enough time passes that it could be invalid.
     
  9. gabeincal

    gabeincal Enjoying Napa life the electric way

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    I think they start working just over 15 mph..
     
  10. NeverFollow

    NeverFollow Member

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    #10 NeverFollow, Jun 16, 2017
    Last edited: Jun 16, 2017
    I wonder how TPMS (Tire Pressure Monitoring System) sensors get energy from?

    May be there is some kind of piezoelectric mechanism to produce electricity.

    Also it make sense that TMS get activated and transmit a signal only when the car is moving.
     
  11. SabrToothSqrl

    SabrToothSqrl Active Member

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    Battery. Prioritize cost over everything. Battery = $0.05. Piezoelectric generator = cool, but at least $0.06-$5.00+

    TPMS: Tire Pressure Monitoring System | Tires Plus

    Direct TPMS - Wikipedia

    Plus, how would that work in a spinning system? once the weight moves to the outside, it would sit there for the duration the tire was over x speed. even if the system moved at low tire RPM, it could cause vibration and would generate very little power...

    Not saying it couldn't be done, but I'm not sure the investment would ever pay off...

    I used to think TPMS was a joke. A knee-jerk reaction to a problem that had other solutions... but TPMS in my S correctly notified me of a partial flat, where I didn't know about it! So... I'm actually kind of liking it...
     
  12. drklain

    drklain Member

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    There are all kinds of low power transmitters out there that are miserly when it comes to battery usage. Batteries literally last for years and years. My suspicion is that the TPMS units work like many of those...the unit is asleep burning essentially no power until it wakes up, measures the pressure and transmits it and then goes to sleep again. Assuming that is the case, it probably has a bit of a pressure switch to detect the car is in motion and if that isn't the case, it stays off. If the car is in motion, it wakes up, checks and transmits pressure something like once every 5 minutes. Hence the fact the TPMS display doesn't update immediately when you power up and you have to drive for a few minutes until all 4 units have woken up and transmitted.
     
  13. Abqnative

    Abqnative Member

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    Thanks for the info and hints. I must have missed it in the document or Tesla assumed that TPMS behavior is common knowledge.
     
  14. Richardbankd

    Richardbankd Member

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    Somewhat on the same topic, when I pull up that same screen I get a tire pressure measure in "Bars" instead of "PSI" Does anyone know how I can change that, or do they all come like that?
     
  15. f-stop

    f-stop Member

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    if you've set your car to display units in kilometers & km/hr, you get Bars for tire pressure; if set to miles & mph you get PSI. Unfortunately there's no separate setting to just choose Bars vs PSI independently (annoying! I wish we could choose)
     
  16. msnow

    msnow Active Member

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    I had a 911 and it just displayed the last known reading.
     

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