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Flat Tire Today

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by wjtracy, Sep 5, 2016.

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  1. wjtracy

    wjtracy Senior Member

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    I might try that...definitely I will take it apart/looks easy....there is a guy on YouTube taking apart a Corolla TPMS you might be thinking of, and that TPMS looks like the same one we use for Prius. That shows the battery on the left and the electronics on the right, so this guided me a little bit deciding how to clamp down with the binder clip. I am confused where the pressure sensor is exactly.

    Looks like a CR2032 in there, but it's the special kind with a solder contact pre-welded onto the battery. So you'd need to order those and try to solder it in. Then it looks like everything is encased with bathroom silicone caulk for water proofing.

    PS- The binder clip still working...got kudos from my wife for turning off the TPMS light, but have not told her what's under the drivers seat!
     
    #21 wjtracy, Sep 12, 2016
  2. ILuvMyPriusToo

    ILuvMyPriusToo Senior Member

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    CR2032 - would be same as the fob, LOL

    I am wondering why the clipped sensor doesn't go to sleep if it isn't turning revolutions . . .

    (I have one in a tire that seems to go to sleep and then forgets to wake up when I start driving, resulting in a TPMS light. I have to bump the pressures up/down and then it reads fine for another few weeks, at which point it takes a nap again.)
     
    #22 ILuvMyPriusToo, Sep 12, 2016
  3. wjtracy

    wjtracy Senior Member

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    Good question...maybe the car just needs to be on.
    When I first used Techstream I would move the car a foot or two, but gave up on that.
    I am using a Desk Top on the front seat via extension cord, so I ain't going too far unless I plug it in to the inverter.
     
    #23 wjtracy, Sep 12, 2016
  4. ILuvMyPriusToo

    ILuvMyPriusToo Senior Member

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    I have a solid TPMS light on the dash but no TPMS DTCs in Techstream. Data seems fine but two of the sensors report low batteries, so I am suspecting that is the cause of the light. I bought two Pacific TPMS sensor replacements on Amazon, but when I enter the new sensor IDs into the ECU it does not seem to see them. I was testing the sensors using your binder clip method to confirm that they were working before having them installed in the tires. I get a "can't communicate with a sensor" DTC and the data from the old sensors remains in place (curiously, it doesn't zero out).

    I can reenter the old IDs and the DTC clears, so all that seems to be working OK, and I have double checked the numbers carefully (and repeated the cycle) so know I am entering them correctly.

    Did you have to press the reset button under the steering wheel to get the car to switch to the new sensor after entering the new TPMS ID codes in Techstream?
     
    #24 ILuvMyPriusToo, Jan 7, 2017
    Last edited: Jan 7, 2017
  5. dolj

    dolj Senior Member

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    No, but you should inflate your tires to the correct pressure and then do a reset so that it calibrates all sensors.
     
    #25 dolj, Jan 7, 2017
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  6. ILuvMyPriusToo

    ILuvMyPriusToo Senior Member

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    Thanks - I get that but at the moment I am trying to test the sensors prior to mounting them in a tire. I don't know why they aren't just live after I enter the IDs in Techstream, unless there is an issue with them.
     
    #26 ILuvMyPriusToo, Jan 7, 2017
  7. dolj

    dolj Senior Member

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    If you have the sensor just loose not mounted in a tire, it probably is sending a low pressure signal, hence the light on. Not sure why no DTC though.
     
    #27 dolj, Jan 7, 2017
  8. dolj

    dolj Senior Member

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    Do your new sensors use the correct communications protocol?
     
    #28 dolj, Jan 7, 2017
  9. ILuvMyPriusToo

    ILuvMyPriusToo Senior Member

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    They are 315 mHz so same frequency. There are aftermarket sensors that claim to cover a large percentage of the market, but if com protocols are very different, then that might be the problem.
     
    #29 ILuvMyPriusToo, Jan 7, 2017
    Last edited: Jan 7, 2017
  10. wjtracy

    wjtracy Senior Member

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    I used the Denso replacement which looked almost identical to the old one, so of course it will be critical to purchase a compatible TPMS replacement. I did not have to fiddle with the Reset button. If you enter the codes properly, and you have the correct replacements, you should see good readings and light go off right away (it takes a couple minutes to show the values).

    For testing purposes, you do not really need to do the binder clip trick. You can just hold the TPMS in your hand and see if it is reading 0 pressure and room temperature in Techstream (after you have entered the codes). If it has values, it is working. It was really squeezing in my hand that gave me the idea that a binder clip could be a fake reading technique.

    If a TPMS is bad, you should see (if I recall) NA for pressure and NA for temperature in Techstream. If you have valid pressure and temperature values (zero being valid pressure), then your TPMS are still OK, and the light may be on for actual low pressure.

    My binder clip TPMS is still working sending a fake reading, so far we only lost one tire's TPMS and it'll be 11 years in July. So we lost one at 9.5 years and the other three are still good at 10.5 years.
     
    #30 wjtracy, Jan 8, 2017
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  11. ILuvMyPriusToo

    ILuvMyPriusToo Senior Member

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    I'll locate an OEM unit and hopefully that will resolve the issue. I am surprised there aren't more uniform communications standards - that is probably what has held back aftermarket sensors and kept the replacement costs high. Thanks to everyone for their replies!
     
    #31 ILuvMyPriusToo, Jan 8, 2017
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  12. RobertK

    RobertK Member

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    The Costco employee with a torque wrench is usually checking for properly torqued lug nuts only. They use an air gun with a torque stick to tighten the lug nuts, and I've never seen them use anything other than a star pattern with the air gun.


    iPad ?
     
    #32 RobertK, Jan 8, 2017
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