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TPMS

Discussion in 'Gen 3 Prius Main Forum' started by Jonny Zero, Oct 1, 2012.

  1. Jonny Zero

    Jonny Zero Giggidy

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    Does the Prius' TPMS employ a sleep mode to conserve battery? I.e., stop transmitting when the wheels are not in motion.

    All the information I see state that they transmit once per minute, there is no mention of a sleep mode.

    Also, I am assuming that the communication is one-way, the TPMS ECU cannot talk back to the sensors to put them to sleep or wake them up. Is this correct?
     
    #1 Jonny Zero, Oct 1, 2012
  2. gliderman

    gliderman Active Member

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    I didnt know they had batteries.
     
    #2 gliderman, Oct 1, 2012
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  3. Judgeless

    Judgeless Senior Member

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    #3 Judgeless, Oct 2, 2012
  4. Jonny Zero

    Jonny Zero Giggidy

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    Yea I saw that article, which is what prompted my question. If Toyota indeed uses a motion cancelled "sleep mode", and I adjust the pressures and reset the TPMS after the car has been parked and tires cooled off for a while, what is 'waking' the sensors to register the new read? One might speculate the change in pressure when you adjust the pressures will wake them, but what if only 2 out of 4 tires needed adjustment, what is waking the other two?
     
    #4 Jonny Zero, Oct 2, 2012
  5. xs650

    xs650 Senior Member

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    A friend has a 2002 Corvette on it's original sensors. I think he is doing better than most people.

    I have seen a writeup on the Corvette forum by a guy that dug the old batteries out of the potting compound, replaced them with new batteries and re-potted them. I don't think I will ever go that far, but it's nice that someone figured it out.
    How to replace TPM Sensor Batteries - Corvette Forum
    Note: May not be applicable to Prii configuration sensors.

    Some more info of limited utility to 99.9% of the population:) is that the Prius TPMS sensors also transmit temperature.
     
    #5 xs650, Oct 2, 2012
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  6. mad-dog-one

    mad-dog-one Prius Enthusiast

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    Is each TPMS temperature readable using a Scangauge?
     
    #6 mad-dog-one, Oct 2, 2012
  7. Judgeless

    Judgeless Senior Member

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    I do not belive you can read the TPMS over OBD2 on the Prius. It is not on the list.

    Welcome to Google Docs
     
    #7 Judgeless, Oct 2, 2012
  8. xs650

    xs650 Senior Member

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    I've done it. I used a Mangoose device with boot-leg Tech Stream software. Both the temperature and pressure.

    I don't know how to do it with more generic devices.
     
    #8 xs650, Oct 2, 2012
  9. Judgeless

    Judgeless Senior Member

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    Does it show the PID using the Toyota Tech Stream software? That would be a nice addition to the spreadsheet.
     
    #9 Judgeless, Oct 2, 2012
  10. xs650

    xs650 Senior Member

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    I didn't use it much and don't remember seeing the PID, Critic is more familiar with the device and software.
     
    #10 xs650, Oct 2, 2012
  11. RobH

    RobH Senior Member

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    TPMS uses the KWP connection to OBD2. Scangauge/ELM can't cope with the protocol that Toyota uses on KWP. The Techstream scantool that dealers use does communicate with TPMS, providing individual tire pressures and temperature.
     
    #11 RobH, Oct 3, 2012
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  12. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    For those wondering why temperature is important, knowing the temperature of the tire helps the ECU adjust for warm vs. cold pressure to avoid alerting at an over-pressure situation due to heat. However, low pressure combined w/ high heat could warn for an impending failure (especially under high weight loads). I have no idea if the ECU is taking that into consideration, but temperature helps offset pressure changes under normal use.
     
    #12 HTMLSpinnr, Oct 4, 2012
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