HELP…so many lights, regen braking pushback, Code P0A74

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by RachaelH, Jun 16, 2023.

  1. RachaelH

    RachaelH Junior Member

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    Dashboard lit like a Christmas tree for a while now but I’m off work for back injury/surgery. Then, today, while I left it running for my daughter while I had a Dr appt, constant beeping started. She said nothing happened beforehand, it just started beeping. When I got to the car, it still moved while in gear but the regenerative braking pushed back and it drove like a pre power braking system kind of jalopy. We limped a few blocks straight home.

    The lights that have been on for months now is engine, brake, traction, etc & rotating check PCS system and check hybrid system messages but no codes were found when checked until now when the constant beeping started (code P0A74).

    it was checked by a mechanic friend (likely a snap-on scanner) and no, no one has the ability to check the hybrid batteries. I know this isn’t much info but it’s all I’ve got right now. Could really use some guidance from your experience on this before I replace inverters, sensors, and HV battery cells just to find out it’s something else.
     

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    #1 RachaelH, Jun 16, 2023
  2. tankyuong

    tankyuong Senior Member

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    download the dr prius app and scan codes
     
    #2 tankyuong, Jun 17, 2023
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  3. Brian1954

    Brian1954 Senior Member

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    It sounds like you have more than one problem with your Prius. You need to get all the trouble codes read. Start by taking your car to a few auto part stores that do free scans for trouble codes and then come back and report what was found. If that does not work, you can always take the car to a Toyota dealership for diagnostics.


    Posted via the PriusChat mobile app.
     
    #3 Brian1954, Jun 17, 2023
  4. ChapmanF

    ChapmanF Senior Member

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    The Dr. Prius app is kind of a specialty app for traction battery preening but not a great choice for a situation like this, because it is very limited in its ability to show you other trouble codes for other things. Here, you would want a more general-purpose scan app or tool that can show all of the trouble codes that you have.

    There is a thread comparing a bunch of those, tested on Gen 2 cars. We don't really have a comparable thread for Gen 3, but some of the better Gen 2 choices are probably pretty good Gen 3 choices too.

    Gen2 OBD2 app review | PriusChat

    For at least the traction, ABS, and ((!)) lights that you have now, you can get those codes right away without any scan tool at all, this way:

    Blink (a/k/a Flash) Codes – How to. | PriusChat

    That would be a start, anyway.
     
    #4 ChapmanF, Jun 17, 2023
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  5. RachaelH

    RachaelH Junior Member

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    2010 Prius
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    II
    Thanks so much guys - I’ll start with Chapman’s suggestion and work out to see what I can dig up. It’s never thrown codes before even when the lights first come on, at least not that AutoZone or my mechanic friend could get on their readers. Hard to pinpoint where to begin without that really. It’s only been to the dealership once and that was almost a several thousand dollar mistake that my mechanic buddy fixed for $80 in parts.

    Thanks so much guys for the insight - I’ll update as I go with what I find.
     
    #5 RachaelH, Jun 17, 2023
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