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P0A08 P0A09 Solved via Inverter Replacement

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by broski, Dec 1, 2019.

  1. broski

    broski Junior Member

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    Hey all,

    I'd like to post this thread purely as a followup to my own problems that I felt were not adequately documented on this forum in the event that someone else runs into the same issue. This pertains to a car that was the victim of a reverse-polarity jump prior to my ownership. Dealer replaced the fusible link but the car still displayed the red triangle, VSC & ABS lights. Techstream showed that P0A08 and P0A09 were both present, along with two other codes (I can't recall these offhand). I believe P0A08/09 to be related to the 12v charging circuit & the car's inability to sense that the charge circuit is functioning, or that it may not be functioning at all.

    The solution was to replace the inverter lower board. I was able to accomplish this with the inverter in the car, and without spilling any fluids! The short instructions are, disconnect all the electrical connections to the inverter (big orange plug first, and allow voltage to dissipate for a day unless you can verify with a multimeter) & remove the three bolts holding the inverter brackets to the car. You can then rotate the inverter up and around such that the bottom panel is accessible (see pictures below). I realize these instructions are short, but best bet is to follow the Toyota service manual for inverter removal (this will cover the cowl/windshield wiper area removal, although this part is quite straightforward) minus the bits about the coolant lines. Also don't worry about flipping the coolant reservoir, it's sealed and will not leak.

    Another small bonus from this whole story is that, if you are buying an inverter for this purpose, you can be a bit less picky about the unit you receive, as the boards rarely go bad without outside intervention. The inverter this board came from actually had a significant hole in the housing from the accident it sustained.

    Last tip: I highly recommend buying a JIS screwdriver set for the amplifier screws on the board - -they strip easily and are held in with a loctite type substance.


    [​IMG]
    Inverter in service position

    [​IMG]
    This is a picture of the board that was removed -- as you can see, the magic smoke has gone missing.

    [​IMG]
    Photo of the board removed with inverter in-situ.

    Fired up the car after everything was done and the only light on the dashboard was the green READY!

    Thanks again everyone. Hope this helps someone out who has a Prius that was jumped backwards.
     
    #1 broski, Dec 1, 2019
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  2. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    Excellent job, and an impressive first post :coffee:

    Thank you for sharing.
     
    #2 SFO, Dec 2, 2019
  3. tubes

    tubes Junior Member

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    Appreciate this. I had the exact same situation, reverse polarity jump then changed the fusible link, new 12v battery, and still all the dash lights. Never had a CEL though.

    Finally downloaded Dr. Prius after using Torque for ever, and got the PoA08 and PoA09 battery codes.

    Will try the inverter swap and eventually post my results.
     
    #3 tubes, Apr 26, 2022
    broski and SFO like this.
  4. tubes

    tubes Junior Member

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    Took the car in, they swapped inverters, replaced the thermostat valve, inverter water pump, tranny fluid exchange, cleaned the hybrid battery fan and replaced spark plugs. No more lights. Well, a P2195 CEL mysteriously shows now.

    Thanks for the thread OP, I always figured it was the inverter but the car drove fine was just a Christmas tree for the last year.
     
    #4 tubes, Jul 11, 2022
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  5. tubes

    tubes Junior Member

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    Nov 2022 update: no check engine lights, car has been driving just fine since the inverter swap and other work. Thanks for the original post @broski
     
    #5 tubes, Nov 2, 2022
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  6. ChapmanF

    ChapmanF Senior Member

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    I encourage anyone with P0A08 after a backwards jump to be very sure to check the 5 amp DC/DC S fuse back in the small fuse block at the + battery terminal. That fuse is one of the things that can cause a P0A08 code, and it can easily be blown in the backwards jump.

    The last backwards-jumped Gen 2 I worked on, the dealer had told the owner the converter was fried and quoted a four-figure repair. Yup, the code was because of the 5 amp fuse.

    As the OP shows, one can also be unlucky and really let the magic smoke out. But be sure to check the small fuse for P0A08 before assuming the worst.
     
    #6 ChapmanF, Nov 2, 2022
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