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Tire pressure sensor

Discussion in 'Gen 3 Prius Main Forum' started by nudriver, Sep 24, 2022.

  1. nudriver

    nudriver Member

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    I have a 2012 (is that 3rd gen?) and my pressure sensor came on. Tires were at 28 instead of 38. Got them filled. Sensor stays on. Why?
     
  2. JC91006

    JC91006 Senior Member

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    Battery on the sensor dies after 10 years
     
  3. nudriver

    nudriver Member

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    So you think it may just be a weird coincidence? And then I just ignore the sensor from here on out?
     
  4. JC91006

    JC91006 Senior Member

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    I would change all of them, it’s a safety feature that you shouldn’t lose.

    a set of 4 roadfar branded sensors is $41 on Amazon.
     
  5. Grit

    Grit Senior Member

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    If holding down the tpms button to reset the pressure level is not an option then you should replace the batteries in all tires.
     
  6. ChapmanF

    ChapmanF Senior Member

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    As that button's purpose is to say "see these pressures in the tires right now? Those are the pressures I want. Warn me if they get much lower than that", any time you've changed your mind about what pressures you want, that's an obvious time to fuss with the button, and any time you haven't, isn't.

    You get different trouble codes for the tire pressure being low and for a sensor battery pooping out. So reading the trouble codes can give you a better idea what's going on.

    If you don't have a scan tool handy that can read them, the Gen 3 TPMS can blink your codes out on the warning light, if you turn the car on with the Tc and CG pins jumpered at the diagnostic port. You can search up lots of threads about that here. Most of them are about the brake ECU, but the TPMS ECU in Gen 3 knows the same trick.
     
  7. nudriver

    nudriver Member

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    You totally lost me. I'm not a car guy.
     
  8. nudriver

    nudriver Member

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    There's a button somewhere I can press to reset?
     
  9. ASRDogman

    ASRDogman Senior Member

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    It's under the steering wheel, next to the OBD port.
    If you kneel down with the drivers door open and look below the steering column
    about even with the seat, you'll see a black button about the siz of a #2 pencil.
    You press and hold that, then start the car. You'll see it flashing a few times, then stop.
    You can let go of the button, and you're all set.

     
  10. Tombukt2

    Tombukt2 Senior Member

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    Just so you know your Toyota TPMS sensors are made by a company called Pacific if you look on the back of your center caps you'll see the oblong circle and the word Pacific in many of your Toyota center caps Pacific seems to make a lot of the wheel and tire parts. A set of Pacific TPMS sensors exactly like the ones on your car are 36 some odd dollars on eBay look for the Pacific logo it's an oblong circle with the word Pacific in it. Look on the back of your center caps the next time you're having your car tires balanced or something and see if you see the word Pacific. I know I bought the sensors on eBay from dealer that sells this brand exactly and when they came to me and I changed them the ones I took out look exactly the same with the same color on the logo and everything.
     
  11. ChapmanF

    ChapmanF Senior Member

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    No. There isn't. If I lost you with everything else, at least this should be clear:

    There is a button under the dash, but it is not some kind of magic reset-things button. It is the button you use to tell your TPMS what you want your normal tire pressures to be.

    So, if you ever change your mind about what normal tire pressures you want, that's a perfectly good reason to play with the button. Air the tires to whatever pressure you want, then use the button, as the manual describes.

    If you haven't changed your mind about the tire pressures you want, then there's no reason to play with the button.
     
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  12. Johnny Cakes

    Johnny Cakes Senior Member

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    FWIW, the sensor light doesn't reset instantly. Don't go crazy until you've driven some.

    While the sensors are relatively cheap, installation labor is not.

    And people have suggested a reset in this thread -- would that work? If the sensor is bad/no battery, it is not reporting any value to the computer, not just a low value. Would a reset cause the computer to accept three values, not four? I don't know the answer to that.
     
  13. Tombukt2

    Tombukt2 Senior Member

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    TPMS sensors cost a lot of money to replace are you kidding the tire place has a flat rate of $7 or something like that per sensor that they have to stick through the hole and tighten up the little screw if you don't want to pay that which I didn't one time I just took my saws off and cut the slot in my tires that were getting ready to be removed by the tire place in about an hour The rims were in my trunk I just sliced the tires screwed on the new sensors took the rims into the place to be demounted and thrown away and the new tires installed The new sensors are already on the rims The guy even asked me what was the deal and I told him I'm not paying $7 for you to screw a ferule down. That's absolutely insane and rather than ask you to demount the tires while I walk over and stick the sensor on which you would then say I can't step in your shop because in the safety insurance reasons. I did it this way. And now the remove tires aren't even good for retreading or good for cores they are seriously trash.
     
  14. ChapmanF

    ChapmanF Senior Member

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    No, there's not really anything to reset, and the only easy button you have under the dash is just for saying "look at the tire pressures I have now, and remember those are the pressures I want."

    If you are getting the warning because of a low tire pressure, well, that will make the warning go away, but only because you just said that low pressure is what you want, which isn't a smart thing to say.

    If the warning light is on for any other reason, that button won't make it go out. But it will leave you with all four of your "wanted" tire pressures now changed to match whatever pressures are in your four tires right now. Which probably wasn't what you wanted to do.

    The TPMS will give you trouble codes that tell you which transmitter is sending a low pressure, or which transmitter isn't sending at all. Those are different codes, so you can tell the two different problems apart. (Regrettably, the TPMS doesn't know which transmitter is at which corner of the car. It only knows them by their ID numbers. So even knowing which transmitter is being warned about doesn't tell you which tire that is. Unless you keep track of that yourself, or go to a tire place and they have a wand to wave over the tires.)

    For a warning that comes on because the pressure is low, the warning won't go out from the pressure rising just a little bit above where the light came on. To avoid having warnings just come and go annoyingly, they have it set up so once the warning comes on, you need significantly more pressure in the tire before it goes out. And it can take a little bit of driving to go out.

    There is a TPMS signal check utility in Techstream that does have the side effect of turning the light out, if everything else is ok and you are just impatient waiting for the light to go out on its own. You might think of that as sort of like a "reset", but it's kind of a long run for a short slide.
     
  15. nudriver

    nudriver Member

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    So not sure what to do.
     
  16. Paul E. Highway

    Paul E. Highway Active Member

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    At least one of your wheels has a sensor with a failed battery. 10 years is a good run. Go to a tire shop and replace all 4 sensors. Safety first!
     
  17. ChapmanF

    ChapmanF Senior Member

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    For starters, tell us which of these two things the TPMS light on your dashboard does:

    blnk.png

    Then we'll know whether the guesses about failed sensors or batteries are on the mark. They give you the second pattern. (They're not the only reasons you can get the second pattern; the trouble codes would tell more. But they'd be a likely guess, if you've got the second pattern.)