Are TPMS values adjustable with Techstream?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Geoffzie, Jun 18, 2021.

  1. Geoffzie

    Geoffzie New Member

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    I just purchased a 2008 Prius in January of 2021 ... But the TPMS light has been on since I got it. I've tried checking tire pressures to no avail ... Even tried disabling the TPMS system to no avail (It's easy to do in other Toyotas)

    I just recently got Techstream, and here's what it shows....

    TPMS.jpg

    Here's my questions ...

    1. I assume that since all 4 tires pressures are shown, that all 4 TPMS devices are working properly and their batteries are good (someone just put 4 new tires on it before I bought it (New TPMS devices too?)

    2. What do the "ID1-2-3-4 initial Threshold of Low-Pressure" values mean? (Is it the pressure at which the light is triggered?)

    3. What does the Threshold of Low-Pressure (Lower Limit) value represent?

    4. Are any of the Lower-Limit values adjustable with Techstream?

    Any input would be greatly appreciated!
     
  2. Mendel Leisk

    Mendel Leisk Sand Pounder

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    My hunch is the nee sensors put in we’re not compatible or not initialized properly.
     
  3. Geoffzie

    Geoffzie New Member

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    Although if they weren't compatible or not initialized properly ... Why would they be showing tire pressures?
     
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  4. mr_guy_mann

    mr_guy_mann Senior Member

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    Look at your pressure value for "tire2" and also at the "lower limit" for that same tire. I THINK that the lower limit values are adjustable (within a range) by performing the TPMS initialization with the button under the steering column. You need to look up the procedure in the owners manual.

    Normally (in most cars) the pressure values are the same as the door jamb sticker, and the light should activate if any tire reaches 80% of that value or less.
    Posted via the PriusChat mobile app.
     
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  5. wjtracy

    wjtracy Senior Member

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    You should be good...I have never seen the TPMS light ON with valid pressure readings....
    However, perhaps the RESET was used to assign a higher alarm value.
    Bump the tire pressure up some or hit RESET.
    If I recall my vehicle alarmed at about 26 PSIA, if memory serves(?) that 26 is default.
    Looks like my tire pressures, but 30 psia is way low for old school Prius owners trying to max MPG..40 was typical.

    If that does not work, we have some interesting advanced topic.
     
    #5 wjtracy, Jun 18, 2021
    Last edited: Jun 18, 2021
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  6. ChapmanF

    ChapmanF Senior Member

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    Your current tire pressures are all low for a Prius—I don't just mean lower than the pump-em-up-like-rocks folks like 'em, I mean lower even than the factory numbers on the door card. You ought to be running those pressures at least.

    Also, your ID 2 pressure is below the low threshold, as mr_guy_mann already pointed out. That'll give you a tire light. :)

    There is a bit of hysteresis built into the system so the light doesn't just bounce on and off all the time. Once a tire has gone below the low threshold and turned the light on, even pumping it back up just over the threshold won't turn the light off. It will have to be several PSI over the threshold. Happily, you can do that here, just getting the tires back to normal pressures.

    The system doesn't give you a direct way to set the thresholds. There's just the SET button under the dash. The way it works is you get the tires to the pressures you want, then hold the SET button, and it adjusts the four thresholds to x% lower than what your current readings are.

    All four tire pressures and temperatures look real, so I don't think there's a transmitter or registration issue.

    If you reinflate all four to normal pressure and the light doesn't go out after a bit of driving, there are some other possible reasons the light can be on. In the Trouble Codes screen, did Techstream show any?
     
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  7. Geoffzie

    Geoffzie New Member

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    ChapmanF, I didn't see any TPMS trouble codes ... But I just started using Techstream yesterday so I'm a little "green". Here's what I read as to the procedure to "reset" the TPMS (after filling tires to correct pressures - I think 35 F / 33 R). I already filled the tires right after I got the car ... But I may not have done the "reset" procedure correctly.

    1. Turn the ignition switch to "ON" without starting the engine.
    2. Press and hold the TPMS reset button located below the steering wheel.
    3. Release the button after the low-pressure light blinks three times.
    4. Leave the ignition turned on for 20 minutes so the computer can calibrate each sensor.
    5. Turn the ignition off after 20 minutes


    It says do NOT start the engine (#1) ... But then it says leave the Ignition on for 20 minutes (#4) ... Can I be driving the car for 20 minutes? ... Or do I just sit in the parking lot for 20 minutes with Ignition ON engine OFF?

    Here's a better screen shot, the one above is hard to read (for my eyes) ...

    TPMS 2.jpg
     
  8. Geoffzie

    Geoffzie New Member

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    Ok, I fixed the problem ... The TPMS light is out. I was doing the "Reset" incorrectly. On many cars, you just turn the ignition on, and hold the Reset button until the light goes out (which I tried initially when I bought the car) ... But not the Prius.

    Here's what I did ...

    1. Filled ALL the tires to 35PSI (I use a dial gauge)
    2. Turn the car ON with engine NOT running. (You press the Power button TWICE ... WITHOUT your foot on the brake - yellow dash lights will illuminate)
    3. Press and hold TPMS Reset button under steering column (on right)
    4. Release the TPMS button after TPMS light flashes three times.
    5. DO NOT turn car off! ... Leave the car ON for 20 minutes to "register" the TPMS sensors.

    (OPTIONAL) I chose to actually drive the car for 20 minutes rather than just leaving it ON for 20 minutes.

    6. With your foot on the brake (Ignition is already ON), press the Power button once, engine will start.
    7. I began driving the car ... After about only 5 minutes, the light went out and stayed out.
    8. You can turn the car OFF.

    New Techstream data (judging from the tire pressures, my gauge might be slightly off) ...

    Thanks for all your help!

    TPMS 3.jpg
     
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  9. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Owner's Manual, page 377:

    upload_2021-6-19_7-0-41.png
     
  10. ChapmanF

    ChapmanF Senior Member

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    Yeah, the "a few minutes" from the owners' manual is more like what I remembered; I sure never heard anything about twenty minutes!

    It isn't 'registering' the transmitters in that process; you can only do that with Techstream (or similar software) over the OBD port, and you need the IDs of the transmitters to do it.

    The SET button under the dash is only going to wait for the current readings to come in from all four (already registered) transmitters, and set each warning threshold to be a certain percentage below the corresponding reading.
     
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  11. Mendel Leisk

    Mendel Leisk Sand Pounder

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    I wish they'd been more specific; read the same or similar in 3rd gen manual, and immediate question was "ok, how many is a few?". Probably sat there a good 10 minutes, making sure.
     
  12. Geoffzie

    Geoffzie New Member

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    Mendel Leisk, yea ... But who reads owner's manuals? (except as a LAST resort!) :)

    I found the "20 minutes" from a CarGurus post.

    "Register" was probably the wrong word ... I realize the initial programming of the sensors is done through Techstream ... Probably "reading" the tire pressures would be better wording.

    And yea, it didn't take anywhere near 20 minutes!
     
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