Exclamation Mark , problem , no error messages

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by sergo, Feb 5, 2013.

  1. sergo

    sergo Junior Member

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    Hello ,

    i`ve got 2006 prius ,

    the car worked fine , there was no problem ,

    today , while driving , Red exclamation mark , yellow exclamation mark appeared on dashboard , and red car with sign on the main LCD screen ,

    i`ve got 2 different OBD scanner/diagnostics , i tried both of them but with no luck , there is no any error/problem returned

    oil is fine,tires are fine,battery is fine( i think ),gas tank is almost full,inverter pump is working ok

    currently car runs fine,but i`m worried about it , i cant think what might be a problem , without error messages :(
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    There are DTC logged, its just that your OBD scanners are not able to pick them up. Since you can't find any obvious problem, I suggest you visit your local Toyota dealer to have the DTC read (assuming the hybrid vehicle warning icon on the MFD is still present.)
     
  3. sergo

    sergo Junior Member

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    Thanks for your reply ,

    actually I can scan for DTC- also , but there are no trouble codes , and yes vehicle warning is still on
     
  4. nh7o

    nh7o Off grid since 1980

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    The DTC may be from one of the many ECU's that only a Prius specific scanner will read. Generic OBDII scanners will not connect to all the hybrid control electronics.
     
  5. sergo

    sergo Junior Member

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    I`ve read DTC before with my tools on this prius , i think brake pads are not in a good shape , can this cause a problem ? wont it write this on MFD ?
     
  6. nh7o

    nh7o Off grid since 1980

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    Yes, a generic scanner will read the generic OBDII engine related and generic ABS related DTC's. But the Prius has a number of other ECU's related to the hybrid system. If there is a problem in those areas, a generic scanner will not read them. Worn brake pads have not been a source of ABS or VSC errors, as far as postings here on PC go. It is not impossible that there is some way for that to happen, though.
     
  7. sergo

    sergo Junior Member

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    Thanks ,

    today when i started the car , all warning lights were off and it did not show up ,
    i will change brake pads,oil and check for DTC-s also
     
  8. nh7o

    nh7o Off grid since 1980

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  9. Britprius

    Britprius Senior Member

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    There is no mechanism to give a DTC for worn brake pads on the Prius.

    John (Britprius)
     
  10. sergo

    sergo Junior Member

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    Hello ,

    Brake pads were ok , we checked it

    marks did show up again ,

    front panel looks like this

    before.jpg

    and LCD screen like this

    [​IMG]


    but there was not any DTC-s again ...

    but when i tried to clear ECU data lights went out , but then again appeared (just for testing)

    Battery shows 11.7V on LCD diagnostics mode

    i remember that first time when marks appeared , i was driving on a little hill and as soon as i pressed gas pedal fully , marks appeared


    any ideas ?
     
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    My advice in post #2 still applies. Obviously your code reader is not able to pick up the DTC, but trust me, they exist if you see those warning lights and warning icon in the MFD.

    Also it wouldn't hurt to replace the 12V battery, but that is not causing the warning lights.
     
  12. uart

    uart Senior Member

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    Measured in accessory mode or ignition-on mode?
    Any other electrical loads at the time?
    How long had the car been sitting (not in ready mode) before the measurement?
     
  13. sergo

    sergo Junior Member

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    we will check tomorrow with toyota`s scanner , thanks

    it was in accessory mode ,
    without additional electrical load,
    1 hour i think
     
  14. uart

    uart Senior Member

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    Ok, that makes the 11.7 volts you measured very low for those conditions. The voltage in Ig-on mode could be as low a 10.x volts, and the voltage could easily dip well under 10 volts as the ECU's are booting. That is likely to cause problems.

    You should watch the voltage display as you hold your foot on the brake and press the power button a second time (to go from acc mode to ig-on mode). Blink and you'll miss it, but you may briefly see the voltage fall alarmingly low.
     
  15. bequa

    bequa Junior Member

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    Hello all,

    The author of the thread is my brother. The car still sees these warning lights,

    Patrick, you were right, we've been able to get a code out with other scanner which reads P0A39.

    P0A39 = Generator Temperature sensor circuit too high ..

    What it could be? Which sensor? Located where?

    Car has been bought wrecked and has been traveling from US to EU during 2 months. As the car has 108k miles on it, could it be transaxle fluid causing this? Maybe it is time to change it right away?
    Or could there be ATF at low level? Though we have checked it by removing drain plug and the oil came out normally.

    Fact is that when the car gets warn this code comes out and stays as it cant be erased unless it cools down.

    Please help!
     
  16. Patrick Wong

    Patrick Wong DIY Enthusiast

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    DTC P0A39 means that a temperature sensor within the transaxle is reading an excessively high temperature. The sensor is a thermistor whose resistance declines as temperature increases. When this code happens, the hybrid vehicle ECU will limit power produced by the MGs in the transaxle to prevent damage.

    Since the car had been in an accident, the most likely cause is a fault in a wiring harness connector to the transaxle which is causing a short. However, since bequa says that the fault only occurs when the drivetrain warms up, that would imply there is a real fault with the sensor itself.

    If the wiring harness is not damaged, then either the sensor within the transaxle or the hybrid vehicle ECU has a problem.

    Although it would not hurt to replace the transaxle ATF, that is not going to fix this particular issue.
     
  17. nh7o

    nh7o Off grid since 1980

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  18. bequa

    bequa Junior Member

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    @ Patrick Wong

    Are you sure that DTC means that the sensor is reading high temp?
    Please check this page .
    The documentation says that
    1. P0A39 = Open or +B short in motor temperature sensor No. 2 circuit
    2. Open or +B short in motor temperature sensor No. 2 circuit = -50C Temp reading
    3. P0A39 = -50C Temp reading .

    Correct me if I'm wrong, please .

    And could u tell me where is this sensor located, can I access it by checking the wiring? I could not find it on ToyoDIY.
    If it is inside the transaxle mechanism, then is it connected through the white connector next to the coolant pump, between inverter and radiator ?

    I need to be sure where to start troubleshooting from ..

    Thanks
     
  19. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, you are right. Looks like the sensor is reporting an abnormally cold temp.

    The sensor is not designated as separately replaceable, so a replacement part is not sold by Toyota. I suggest you find the wiring harness connector at the transaxle, remove it, and measure resistance of the sensor to see if it is reasonable given the ambient temp. The repair manual shows the various connections made by the connector. If the sensor is good, test the wiring harness as suggested by the repair manual.
     
  20. bequa

    bequa Junior Member

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    It is kinda funny now, we know that checking the connectors and wiring is must when u buy a wrecked car, moreover if its gas/electric!

    We could measure and see that one of the wires was cut/not connected at transaxle connector!

    We will re-solder it as Toyota factory does it and get back to you with the results!

    Thanks to all!
     
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