Not sure what this warning light signifies

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by Sierra_Lady, Sep 19, 2021.

  1. gromittoo

    gromittoo Active Member

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    Location:
    philadelphia
    Vehicle:
    2012 Prius v wagon
    Model:
    Two
    In my case, I need actual TPMS ID, not just where the tire came from. This is because I own two extra wheels with tires on them. About a month ago, I ran over a six pack of bottled beer in the road that fell off of someone's car. For a while, it was just a slow leak. This meant the light came on every every two weeks or 1000 miles, and I pumped it back up. Last Friday, the piece of glass finally worked its way to substantial leak, and I had a total flat, when I was expecting to start driving again.

    I pulled a wheel with a usable tire out from behind the garage (important: more than 50 feet from where I park my car), and swapped wheels. Of course the Tire light cannot go out until I changed the TPMS ID in the car computer with Techstream, which I did. I left the dead tire next to the driveway, and I went Ubering.

    There was a second issue that required techstream, because a new error code got set. I had removed the id of the affected tire using techstream, and entered the correct ID. However I then drove the car out of range of the TPMS sensor with 2EFF7C2 (the dead tire), but later Friday evening, that TPMS ID was seen again when I parked in the driveway next to the dead tire. This somehow caused an error code in the TPMS system about loss of communication with a transmitter. The code should not have been set, because the old ID was no longer in the computer, and the new ID was entered. Techstream allowed me to delete that error, and the light stayed out.

    I have thought some more about the "loss of communication with a transmitter" error. The wheel from the back of the garage had been sitting there for over a year. Without being on a moving car, the battery in the sensor might have been low. I recall that on Friday, techstream showed the new ID on the data page, but no tire pressure or temperature data for that wheel, even after 10 minutes. The replacement tire had enough air according the the gauge on the pump, so I drove away. 10 miles later, the light when out. The next afternoon, the light was on again. I drove again but the light stayed on until I had a chance to investigate on Monday.

    When I had a chance to investigate. I found that (according to techstream) the tire had 28 lbs, which is low, but more than the 26 lbs threshold I have set. I found my good tire gauge, and set all the pressures correctly. That is when I noticed the "loss of communication with a transmitter" error was there. Clearing that error made the light go out and stay out. Wish I had taken a screenshot, to see if it contained the ID of the old transmitter.

    Feel free to suggest experiments I can try when I get around to buying two new tires. At that point, I will be changing at least one one of the TPMS IDs in the computer.
     
  2. Brad from Ohio

    Brad from Ohio New Member

    Joined:
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    Location:
    Cleveland
    Vehicle:
    2011 Prius
    Model:
    Four
    Got tired of looking at the warning light, particularly at night.
    After 1 TPMS sensor went bad a few years back, replaced all 4 with new OEM sensors when new tires were being installed.
    Didn't feel like dropping $100+ at the Stealership for something I should have the ability to do myself.
    Tried the TPMS Reset button, and discovered it's useless.
    Recently had a tire store use their software to reset it, but the indicator came back on a few days later.
    Evidently the software to properly reset the sensors is proprietary.
    I finally put black electric tape over it, and wish had done it sooner.
    Check the tire pressures weekly, so got it covered. No thanks TPMS indicator!
     
  3. vvillovv

    vvillovv Senior Member

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    Vehicle:
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    Prime Plus
    @Brad from Ohio the app Tire Assistant at google play (sorry iphone users) will allow you to read the new sensor ID's - tire pressure and the temperature, even though the sensors ID's are not properly pregrammed into the cars ECU. Can save you from having to manually check tire pressure once a week.
    You;d also need a ODB2 bluetooth adapter like a ODB2 panlong or an OBDLink LX - both available at ebay and amazon.

    I put tape over mine too, but somebody pulled it off on me.
     
  4. gromittoo

    gromittoo Active Member

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    Vehicle:
    2012 Prius v wagon
    Model:
    Two
    If the tire store entered one of the TPMS IDs incorrectly, and you pressed the TPMS reset button, you now have a "Permanent fault" that will keep the TPMS light on. The purpose of the TPMS reset switch is to set the "trigger tire pressure threshold" for the light to come on.

    IIRC, the procedure goes something like this: Say you want to have the light come on when the pressure drops below 26 lbs. You would set all of your tires to 26 lbs, and then press the TPMS button. With the new "low Pressure" threshold set, you would set the tire pressures to the correct values, and the light will go out. Toyota gives you this button because the correct tire pressures are different on the front and back on a Prius v. The button is there for when you rotate your tires every 5000 miles.

    There are 4 TPMS IDs stored in one of the car's computers (The main ECU or the TPMS computer behind the glovebox). If the tire shop that "Fixed" your TPMS entered one of the IDs incorrectly, the TPMS computer will report that it can't communicate with the incorrectly entered sensor.

    I tried that app on my 2013 Prius V, and it could not communicate with the TPMS computer. Someone on this forum told me that the TPMS Computer is not on main bus on my 2013, but is on what I think is called the "K bus". It could be that my $25 ELM 327 ODBII adapter just isn't good enough to access that bus, and I should spend $55 for the recommended adapter. My adapter works fine with Torque Pro (When I have not misplaced it), so I have not invested in a more expensive ELM 327 adapter.

    I own Two Prius v's, and I have 2 spare rims with full size tires (total of 10 rims). I need a reliable way to keep the TPMS IDs up to date. I have painted the TPMS IDs on the rims where they are hidden when the wheel is on the car.

    I solved the problem by buying the cable to connect a Windows 10 laptop to the ODBII port, and got Techstream running. These cables have gotten pretty expensive recently because of the "Supply Chain Shortages". Techstream allows you view and enter the correct TPMS ids yourself, and allows you to do almost everything the dealer can do. It is a PITA to set up, but once the driver is installed, it is pretty good. A phone app would be more convenient, if it would allow you to reprogram the TPMS IDs.
     
  5. vvillovv

    vvillovv Senior Member

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    I was thinking the same thing. But what would the dealers do than? Charge uninformed customers $200 to reprogram?
     
  6. gromittoo

    gromittoo Active Member

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    Location:
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    Vehicle:
    2012 Prius v wagon
    Model:
    Two
    Most tire shops have the ability to do the reprogramming, but the tools are too expensive for a DIY'r. My local Sears wanted $25 to do the reprogramming when I switched wheels. I paid an independent tire shop to get the IDs using their expensive tool. I painted the IDs on the rims in a place you can't see. Then I can use Techstream to reprogram them when wheels are swapped.

    This saved me once when I was Ubering at 8PM on a Friday night, and ripped a hole in the sidewall of a tire. I could not afford to wait until Monday, and driving on a donut is a no-go with Uber. I drove home on the donut, swapped in a spare wheel with a good tire, I then reprogrammed the IDs with Techstream... and no tire light. I only lost 2 hours, and I was back making money.
     
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