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P0A08 error code

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by whodat, Sep 13, 2010.

  1. whodat

    whodat Member

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    Previous thread (with new subject title) on my 06 Prius losing steering and brakes while driving with multiple errors (red triangle, battery, etc.) while braking on steep down hill section of hwy 17 (mountain road). Took car to dealer but dealer could not find the root cause.

    Print out from dealer:
    131297 found code P0A08. dc/dc converter status circuit. checked aux battery-passed load test. Check cable connection from auxiliary battery terminal - cables connections are secure. Checked inverter water pump coolant level and operation-pump is working.

    So I had them replace the 12V aux battery. So far no relapse of this problem with one day driving with the new 12V aux battery. I am not convinced that this is the root cause.

    Galaxee and Patrick Wong had previous threads something about DC/DC converters overheating when the inverter pumps failed - and perhaps that is closer to the root cause of the issue my 06 Prius is having.

    Thoughts?
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I suggest that you inspect the inverter coolant pump yourself, to verify that it is working. This is easy enough to do:

    1. Make the car IG-ON (from IG-OFF, press the POWER button 2x without depressing the brake pedal.) All of the instrument panel warning lights will be on.

    2. Open the hood and look for the inverter coolant pump behind the driver's side headlamp. Listen for the sound of the pump running (should sound like an aquarium pump and you should not hear air bubbles.)

    3. Look at the inverter coolant reservoir and note turbulence in the fluid which shows the fluid is circulating.

    Also note that the original 12V battery passed the "load test". This is why I suggest that owners not bother to pay for this test at the dealer, if there are any questions about the battery just replace it.
     
  3. whodat

    whodat Member

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    I checked the hose between the driver side headlamp and the fuse box and noted some slight vibration when I put my finger on it - so I am guessing (if that's the inverter coolant pump hose) its working.

    Which coolant reservoir is the inverter coolant - the yellow fluid reservoir?
    Thanks
     
  4. 2009Prius

    2009Prius A Wimpy DIYer

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  5. gabrielino

    gabrielino New Member

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    Your car and city caught my eye.

    I just bought a 2006 Prius and I live in Aptos too. I get back there in mid may. Perhaps we can exchange some info?
    gabe
     
  6. kutcht1

    kutcht1 Member

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    Question for the original poster or anyone else who has had the P0A08 code. Did you also get a high pitched alarm tone?
    TomK
     
  7. ozmatt

    ozmatt Active Member

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    Hi Kutch, this is a 14 year old thread so the original poster might not be around! but to answer your question YES! i get the high pitched alarm tone along with P0A08 (and others) randomly every few months, im not 100% sure but think the alarm is part of the brake master warning once the aux battery gets down to about 10 or 11v the brake system has a hissy.

    Matt
     
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  8. kutcht1

    kutcht1 Member

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    Very interesting ozmatt, in my searching I have found very few people mention the high pitched alarm tone. Mine has not happened again since that first time and I have done nothing except some prodding and pocking around. Seems strange that Toyota would put that system of alerting the driver of something like that and it turn out to be what seems like most times as nothing more than a hiccup.
    TomK
     
  9. ozmatt

    ozmatt Active Member

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    Hi Kutcht1

    I guess it's to make you immediately aware that something is very wrong! and potentially dangerous.

    One of our cars was doing this every once in a while and it went on like this for a couple of years believe it or not, turned out the 12v aux battery was actually the cause all along and it hung in nearly dead for years getting worse and more frequent towards the end of its time.

    ..Never trust the 12v aux battery in a Prius because they need so little power to READY detecting a weak aux battery can be very difficult

    Matt

    Posted via the PriusChat mobile app.
     
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  10. kutcht1

    kutcht1 Member

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    Thanks again for the response Matt. I will keep a close eye on the 12v this summer and will for sure check things closer to winter! It has not done this since and voltage stays well above 12 volt but battery is over 5 years old now.
    TomK
     
  11. retirednongeek

    retirednongeek New Member

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    Hello! I am hoping even though this an older thread, someone will be able to assist me.

    Our 2004 Prius recently had the BRAKE, ABS, RED TRIANGLE, warning buzzer go off while my wife was just backing out of the carport, so she used another car for her errand instead. A few days later it seems to start and run OK, so I drove a short distance until same symptoms appeared. First had it towed to a repair shop (that had replaced ABS 18 months earlier) and they said it was not an ABS issue, but a low voltage issue. I replaced the 30 month old 12V auxiliary battery and still had low voltage codes, but not as many. From there had it towed to dealership. After 2 days they said after charging the new 12 volt battery, it checked out fine.

    Now, a month later, same problem and warning lights.

    After new battery was installed, I ran the auxiliary battery tests by accessing the diagnostic tools using the multi-function display, and all voltages of the 12 V battery seemed within range (static test, under load, and while charging).

    Now the tests show about 11.5 volts or less, even when charging.

    I checked the inverter/converter coolant pump as described in earlier post, and could only hear a slight hum and feel a slight vibration. Could see no "gurgling" at the coolant reservoir.

    Is it likely the inverter/converter is no longer doing its job? Anything else it could be?
     
  12. Brian1954

    Brian1954 Active Member

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    If you want help, you need to post the trouble codes that are causing the warning light to turn on. Everyone will just be guessing what your car's problem is until you post the trouble codes.
     
    #12 Brian1954, Aug 14, 2024 at 1:29 PM
    Last edited: Aug 14, 2024 at 3:29 PM
  13. retirednongeek

    retirednongeek New Member

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    Thank you. The dealer report showed error code P0A08 at the time they had car a month ago. See attached copy of report. I'd be willing to invest in a scanner, if I could find one best suited. My knowledge of scanner types, brands, and terminology is pretty limited. Open to any suggestions or recommendations. Does the inverter water pump sound like a possible cause, based on my recent inspection of no turbulence in reservoir?

    Trouble Code Report.jpg
     
    #13 retirednongeek, Aug 14, 2024 at 1:57 PM
    Last edited: Aug 14, 2024 at 2:09 PM
  14. bisco

    bisco cookie crumbler

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    check inside the inverter coolant reservoir for fluid motion with the car 'on'.
    it could be that the inverter is not working properly. they are cheap enough salvage if it needs to be replaced.
    it will take more testing to determine the problem. you may need a prius aware scanner, not sure what your shop is using.
    see post #2:

    p0a08-dealer-clueless.151186
     
    #14 bisco, Aug 14, 2024 at 2:43 PM
    Last edited: Aug 14, 2024 at 2:51 PM