1. Attachments are working again! Check out this thread for more details and to report any other bugs.

TPMS ( Tire Pressure Monitor System ) Problem

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by TheForce, Jul 19, 2007.

  1. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    I'm having an issue with my TPMS light on the dash. It keeps coming on after I reset it and I have good air pressure. I drove all the way to hybridfest with this issue. This happened before about a week ago after I installed my PC. This was also just after I topped off the tires to 44,42. I thought maybe I just needed to reset for the "new" air pressure but now after I reset the TPMS it comes right back on after driving for a while.

    There are only two things I can think of that may cause this issue. Since the sensors are wireless I think maybe my PC may be emitting some RF interference causing the TPMS receiver to think it has lost a signal. A simple form of unintentional RF jamming.

    The other option is that one or more of the sensors are bad. If this is the case I will just have to wait until I get home and get an appointment with my Toyota dealer.

    Does anyone know what frequency the TPMS emits?

    Anyone have a Scan Tool at hybridfest? I think I read somewhere that the Scan Tool can read all four sensors plus the PSI. Dont know where I seen that. I'm trying to search my shop manual PDFs but my laptop is very very very very sloooooooooooow. Been searching for "TPMS" for about 30 min now :( Its only a 800mhz PC. I think I might just have to go out to my car PC and do a search on that 2ghz machine.
     
  2. NoMoShocks

    NoMoShocks Electrical Engineer

    Joined:
    Jan 21, 2007
    1,292
    82
    11
    Location:
    Camas, WA
    Vehicle:
    2010 Prius
    Model:
    IV
    <div class='quotetop'>QUOTE(TheForce @ Jul 19 2007, 07:19 PM) [snapback]481969[/snapback]</div>
    Is there any posibility that you left any connectors unplugged when you had the whole dash apart? It is scary to try and give advice to "The Force". You are legendary you know.

    I think you could rule out the electromagnectic interfeirence question by removing power from the Auto PC for a few days and see if the problem goes away. That may be the fastest way.
     
  3. galaxee

    galaxee mostly benevolent

    Joined:
    Mar 14, 2005
    9,810
    466
    0
    Location:
    MD
    Vehicle:
    2005 Prius
    i seriously doubt we'd be able to keep a scantool for 10 days for hybridfest and the remaining time we'd be up visiting family or i'd see if we could bring one.

    what if you turn off the pc? does that fix it?
     
  4. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    I havnt tried leaving the PC off for a extended period of time yet because thats where my tunes are. I don't like the radio and I don't have any CDs anymore. Since I don't want my PC on for the MPG challenge I think I will just do another reset and see what happens on the 30 mile trip.

    I'm sure I hooked everything back up in the dash when I had it apart. Looks like the TPMS ECU is in the dash. If I have time I may just take my dash apart after the MPG challenge if I still have the issue to see if I did miss a connection.
     
  5. FL_Prius_Driver

    FL_Prius_Driver Senior Member

    Joined:
    Jun 17, 2007
    4,319
    1,527
    0
    Location:
    Tampa Bay
    Vehicle:
    2010 Prius
    Model:
    I
    Are batteries in the sensors and one of these may have gone bad?
     
  6. 007Prius

    007Prius New Member

    Joined:
    May 23, 2007
    32
    0
    0
    Have you checked your spare tire lately?
     
  7. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    That would be hard to determine with out the Scan Tool.

    The spare does not have a TPM does it? I'm pretty sure it don't.

    I tried resetting the light again and failed to do so. I'm starting to think I may have the connector disconnected or it may have come loose.

    I will first hunt down where the connector is and see if its all hooked up correctly. I'm hoping that there is a connector back there where I can easily get to it. If I have time I might try to do that while I'm here at hybridfest. If I don't have time I'll just wait until I get home and while I'm at it I will try to give the EV light another try by creating a simulated circuit.
     
  8. 007Prius

    007Prius New Member

    Joined:
    May 23, 2007
    32
    0
    0
    <div class='quotetop'>QUOTE(TheForce @ Jul 20 2007, 09:16 PM) [snapback]482601[/snapback]</div>

    My Tundra has one I would think the Prius does too. It's a good idea since most people never check the spare tire so having a sensor in the spare reminds you to check all 5 tires so if you get a flat tire you know you got a good spare to replace the flat.
     
  9. apriusfan

    apriusfan New Member

    Joined:
    Apr 8, 2007
    6,050
    205
    0
    Location:
    S.F. Bay Area
    Vehicle:
    2007 Prius
    <div class='quotetop'>QUOTE(mike m @ Jul 20 2007, 07:45 PM) [snapback]482615[/snapback]</div>
    The spare tire (at least in the 2007 Prius that I have) has a 60 psi rating which is way higher than the pressure for the rest of the tires. If there was a TPMS sensor in the spare, the TPMS would constantly light up the warning light. The TPMS looks for a variance from the values transmitted by the individual sensors mounted in each tire. Even at 40 psi for the main tires, 60 psi in the spare tire would trigger a warning light, so I tend to doubt that there is a TPMS sensor mounted in the spare tire.

    Following are my guesses for the resolution of the problem:

    1. Sensors in each wheel are not registered with the TPMS computer.

    2. Failure of the battery that powers each sensor. I know it is supposed to be a 10 year battery, but things have been known to fail pre-maturely.

    3. Interference by an external source (computer?).
     
  10. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    Well after another reset it takes a good ~30 miles before the light comes back on. I made an appointment with my local dealer. I have unplugged my PC today so there wont be a chance for interference when they test it tomorrow.

    This is going to run me somewhere between $30 and $100 depending how long they take. I'm going to tell them all I really need is to confirm the scan tool can read the four sensors and their pressure. If it can do that then I know my PC is causing the interference. If thats the case I will just see if they can disable the TPMS. I don't really need it because I check my pressure often enough that the TPMS is basically useless to me.
     
  11. galaxee

    galaxee mostly benevolent

    Joined:
    Mar 14, 2005
    9,810
    466
    0
    Location:
    MD
    Vehicle:
    2005 Prius
    disable tpms? :lol: if only. speculation is that you can do it by unplugging the ecu, but it ties into so many other things that who knows what would happen. you could be the first! it's right next to the ps ecu. says tpms or something along those lines on it.
     
  12. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    Well if it cant be disabled or tricked into staying off some how I guess I can give unplugging a try. If that don't work I can always disable the idiot light by desoldering a few things and adding a switch in case I need to enable it again. If I have to go that far I would also try to enable the EV light again while I'm back there.
     
  13. 007Prius

    007Prius New Member

    Joined:
    May 23, 2007
    32
    0
    0
    <div class='quotetop'>QUOTE(galaxee @ Aug 1 2007, 07:55 PM) [snapback]488968[/snapback]</div>

    I'm really suprised that someone has not figured out how to disable the TPMS in a Prius, other Toyota's are just a matter of grounding the TPMS LED wire, is the Prius much different?
     
  14. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    OK I'm back from my dealer and I still don't know whats causing my problem.

    First I had to fix their Techstream computer because someone flipped the screen resolution so the screen was in the vertical position instead of the regular horizontal and no one knew how to flip it back. This is a simple proble for me to fix because it happens every once in a while where I work.

    Next we tried reading the transmitters in the tires. We was able to read all of them just fine. I was amazed with the program they used. It read the PSI with in .1psi. Its pretty cool. It also had the pressures that tripped the TPMS light. Everything there said it would trip when pressure dropped %20 from my current pressure.

    Then I tried turning on my PC with both bluetooth and wifi enabled. The Techstream computer was still able to read all the pressures in real time.

    So now I'm left with Wth. We went over a few ideas and one of the things I'm going to try is lowering my tire pressure back down to the low 40s to high 30s for a while. Another idea is that maybe going over bumps in the road might cause it to trip the TPMS.

    I will continue to diagnose the issue and post results when and if I get them.


    I really want a Techstream or heck even the ScanTool. <_< Will someone buy me one? :D
     
  15. FL_Prius_Driver

    FL_Prius_Driver Senior Member

    Joined:
    Jun 17, 2007
    4,319
    1,527
    0
    Location:
    Tampa Bay
    Vehicle:
    2010 Prius
    Model:
    I
  16. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    Well after about 200 miles the light has not come back on. I have not even changed the tire pressure yet. I think I will ride this one out and if I get the light again I will drop the pressure and do some further diagnostics. I guess I just needed to take the car to the dealer and scare it a little.

    On a side note I really think Toyota should include the tire pressure on the MFD some where. The Techstream computer was able to show all 4 plus room for a 5th sensor with psi readings like 40.3psi. What would be interesting is if the Prius can really handle a 5th sensor in the spare tire. I should have asked the tech while I was there.
     
  17. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    Here is a quick update.

    I never did drop my pressure down to see if that would fix the problem. I have yet to see the light again. Nothing has changed since I took it into the dealer.
     
  18. TheForce

    TheForce Stop War! Lets Rave! Make Love!

    Joined:
    May 30, 2005
    3,461
    537
    0
    Location:
    Wheelersburg, Ohio
    Vehicle:
    2006 Prius
    Model:
    N/A
    Here is a quick update.

    I never did drop my pressure down to see if that would fix the problem. I have yet to see the light again. Nothing has changed since I took it into the dealer.
     
  19. mikemartyo

    mikemartyo New Member

    Joined:
    Aug 11, 2008
    3
    1
    0
    Location:
    Syracuse NY
    Vehicle:
    2008 Prius
    I am getting a set of snow tires for my prius (08) and i am saving the $345 and not getting the TPMS installed.

    Personally i am going to put black electrical tape over the light in my dash
    Mike



    I just found this link that may help you - on the corvette forum -

    now i know they are corvette guys, but they have a novel solution.

    Quote:
    Originally Posted by NORTY
    Here's a possible solution for you to run any tires at any pressure on any rims you want.

    Remove the 4 TPMS and get yourself a piece of PVC pipe and thread a schrader valve in one end and a cap on the other. Throw the sensors inside and pump it up to 30-38PSI. Throw the pipe bomb into the back of the car somewhere and you should be able to drive your car without limits on performance. Now, you might need an attorney if you get pulled over with a "suspicious device" in your car but hey, that's what it takes to drive your car nowadays!


    Believe it or not, that is a suggestion the GM/Corvette folks at the Birthday Bash suggested also - PVC pipe with 4 spare sensors installed stashed in the back. You'll still need a 'training' tool each time you use the pipe to train the sensors for your car. The GM guy said to screw the sensors into the pipe and use one of them to pressurize the pipe. Makes it easier to train them also.

    When through racing, install the street tires/wheels, retrain the sensors (take out the pipe) and press on.
     
    Max Pivnenko likes this.
  20. walterm

    walterm Active Member

    Joined:
    May 17, 2007
    466
    202
    34
    Location:
    NJ
    Vehicle:
    2022 Prius Prime
    Model:
    Limited
    Depending on where you store your non-snow tires you may not need to - I have a set of non-TPMS wheels/snow tires, but I think because the car is close enough to where the TPMS wheels are stored it 'reads' them when I'm parked in the driveway.

    the only time I ever see the tire pressure warning light is if I drive continously for more than an hour or so, then the lack of signal must cause the TPMS to flag 'something is wrong'. But my normal commute is ~35 minutes, so it doesn't light up on my ride to or from work.