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Surprised by P0AA6

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Tbkilb01, May 9, 2023.

  1. Tbkilb01

    Tbkilb01 Active Member

    Joined:
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    Location:
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    Vehicle:
    2011 Prius
    Model:
    IV
    Meant p0AA6
    2011 touring 206K lit up the MIL after I was servicing hybrid battery and cooling fan... just getting ready for summer heat. It has the solar pKg but it still gets hot in

    View attachment 240935

    As I removed battery module post covers I saw them... the mean greenies attacking the nuts!


    View attachment 240936

    View attachment 240937

    Close up shows all the detail. I decided to take the ole toothbrush Method for a shortcut in car servicing...with baking soda solution. View attachment 240938
    Scrubbed both sides but I left the batteries connected up in series like a dummy ...rookie mistake and very dangerous .. a BIG NO-NO... but I did remove the big ORANGE INTERLOCK ! That I did do. And I was using plastic...
    I caught most of the greenies and sprayed a lil battery post cleaner for measure. I even unscrewed a few nuts to verify.. looked good behind them -no green!... View attachment 240940

    View attachment 240942

    Gotta ketchem all! like Pokémon!
    Decided to dry off battery pack with air nozzle..
    Don’t want that corrosion seeping into wires/harness...
    View attachment 240943


    I then went to fan and it had no big stuffy hairy linty wrapper stuff in it so I decided to use blow nozzle on it as well.

    View attachment 240944




    I blew it out with nozzle too.
    So then I Put Prius in READY mode and all seemed good ...till the triangle lit up with MIL...
    with in minutes
    Oops !
    Went back disconnected powers..retraced my steps. Thinking 12v battery low so swapped with another... still the MIL is lit up!
    Connected the AUTEL and sure enough p0AA6
    In the hybrid control module! Decided to step back and search code description and possible causes... That’s not good! Anywhere from module leakage/failure to grounding out...to using mega ohmmeteres under hood ... doesn’t sound like allot of fun! but I did read somewhere that one possible cause could be in the BATTERY COOLING FAN module ...
    Just then a big light lit As I saw myself watching the fan spin out of control Just as I turned on air nozzle If just for a millisecond... till I put my thumb on it.
    So I thought ... hmmmm... maybe I fried it? Oh well, I can just swaptronics the one out of my 2010 parts Prius and eliminate that leg of troubleshooting... would not be time consuming at all!
    But First I decided to use the AUTEL to control fan on thru its 6 speeds and back to zero....
    I sat in seat fingers crossed and eyes closed as I put Prius into READY mode .
    Just as I looked up from the SCAN TOOL .......to the DASH...the MIL TURNED OFF!
    I checked for codes ...NADA.. none! Drove car down driveway a bit then put in maintenance mode for while...revving it up ... powered down turned back on ..left in READY mode and still no codes...
    I heard To not let the fan spin out of control but I usually remove to clean... I should’ve at Very least disconnected it!
    Sometimes if it ain’t broke don’t touch it works
    but then I would never have seen the mean greenies attacking the traction battery ...hunky.. coincidence... luck... intermittent... only time will tell . For now...WHEW!
    I’m gonna do a repeat to my red 2011 touring 96K also and clean EGR/cooler and install catch can next couple of days... I gotta let today sink in. Hope I have better luck!
     
    #1 Tbkilb01, May 9, 2023
    Last edited: May 9, 2023
  2. ChapmanF

    ChapmanF Senior Member

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    Vehicle:
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    Model:
    IV
    What led you to choose baking soda?

    Often people use that on car 12 volt batteries, which use a strong acid electrolyte, because baking soda is a base and helps neutralize any leaked acid.

    The Prius traction battery uses a strong base electrolyte, so scrubbing with another base doesn't do anything to neutralize it. Boric acid solution is recommended there.

    Only because you can read "somewhere" pretty much anything about any trouble code. You waste less time when your "somewhere" is the repair manual for the car. ;)

    The other things you were reading about (leakage from a module, insulation deterioration, testing things with meggers) were pretty much right for P0AA6. Whatever you read about the battery cooling fan and P0AA6, not so much. That fan runs on 12 volts, so it can't be a source of a high-voltage isolation fault.

    You probably created a conductive path from some module terminals to the case with your baking soda solution. It may have dried out and be ok now, or ok for a while. If the code comes back, try to get the INF code that goes with it; that helps you know which of four basic areas in the car to look in. If you don't get the INF code, you have all four possibilities to check.
     
    #2 ChapmanF, May 9, 2023
    Tbkilb01 likes this.
  3. Tbkilb01

    Tbkilb01 Active Member

    Joined:
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    Location:
    Louisiana
    Vehicle:
    2011 Prius
    Model:
    IV
    View attachment 240945 View attachment 240945
    yeah figures I have my fingers crossed though
    Not a good feeling at all ... I read of those codes
    I leaning more towards your scenario LOL
    Last time I cleaned some it was in vinegar and it was not pretty...looked like ate the finish off... installed em anyway. I just figured corrosion is corrosion... it wasn’t everywhere yet either.. anyway, That’s what I get for thinking...
     
    #3 Tbkilb01, May 9, 2023
    Last edited: May 9, 2023
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