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Replaced battery after P0a80 error, now engine wont start and check hybrid system light is still on

Discussion in 'Gen 3 Prius Technical Discussion' started by Lukesapp, Mar 15, 2024.

  1. Lukesapp

    Lukesapp New Member

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    OK so I am not completely dumb, but starting to feel like it. I had the check hybrid system light come on and took it to O’Reillys auto parts and got the P0A80 code. Its got 115,000 miles, so they suggested replacing the hybrid battery pack. The engine was still running fine but I could tell I had no electric drive power(engine stayed on always). I put the hybrid battery in today and when i went to start it up the engine didn’t fire and the other warning lights came on. Wont go into gear or anything. So somehow i made it worse. I checked the disconnect to make sure it was seated right. I have a bluetooth obd2 reader and it still has the code and reading my 12 volt at around 10.5. I thought disconnecting the 12v would have cleared the code. So im wondering if i missed something obvious or possibly lost enough charge in my 12v to stop it from starting and charging the new battery? The battery is dorman brand. Its remanufactured (thought i was buying new) could that be the problem? Unfortunately i spent all my money on the battery so im really stuck figuring it out myself. Thanks in advance for any help
     
    #1 Lukesapp, Mar 15, 2024
  2. JC91006

    JC91006 Senior Member

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    Try charging the 12v battery, 10.5v seems very low and may not be enough power to start the car
     
    #2 JC91006, Mar 16, 2024
  3. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    The Dorman rebuilts don't have a great reputation, but they also don't usually show up DOA and they do have warranties. Better than nothing.

    I suspect that you are actually being presented with a different code than you were originally. Many Prius diagnostic codes come in two parts: the main code and then a sub-code.

    Many cheap code readers are not sensitive to sub-codes, so you wouldn't know the difference from one to another unless you checked with a full-fledged reader.

    There's a thread around here with further info on cheap ones that can pull the detailed sub-codes.
     
    #3 Leadfoot J. McCoalroller, Mar 16, 2024
  4. ASRDogman

    ASRDogman Senior Member

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    The 12v battery likely drained because the dome lights were on when you replaced the hybrid battery.
    A 5 amp or less amg charger should bring the 12v back up to charge. Charge it for 3 or 4 hours should
    be enough to get the car to start. But 8 hours would be best. You really want it fully charged.
    Is there a warranty on the 12v battery?


     
    #4 ASRDogman, Mar 16, 2024
  5. ChapmanF

    ChapmanF Senior Member

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    If you went to start it and nothing happened, no lights came on, or came on dimly or flickeringly, the usual beepers sounded weird, and that kind of thing, it would strongly suggest a discharged 12 volt battery.

    If you go to start it and it lights right up, shows a triangle and other warning lights, and does not show the READY indicator, that suggests there is enough 12 volt power for the car to boot up and notice something out of whack in its checklist for going to READY. Sometimes that means you missed something obvious, sometimes you missed something nonobvious. Either way, the trouble codes should point to it.
     
    #5 ChapmanF, Mar 16, 2024
    Brian1954 likes this.
  6. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Have you still got the original battery?
     
    #6 Mendel Leisk, Mar 16, 2024
  7. Lukesapp

    Lukesapp New Member

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    Thanks for the suggestions! After putting the 12v on a low amp charge for an hour or so and it started/charged the ev battery as normal. I appreciate all the input, this forum was extremely helpful.
     
    #7 Lukesapp, Mar 16, 2024
    Mendel Leisk likes this.
  8. ASRDogman

    ASRDogman Senior Member

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    You should charge it longer, at least 6 hours. Give it a full charge.
    Then the inverter doesn't have to work so hard trying to charge it up.



     
    #8 ASRDogman, Mar 17, 2024
    Mendel Leisk likes this.
  9. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Yeah, if you have a “smart” charger, it’ll assess the (12 volt) battery and run a multi-stage charging regimen, and typically that’ll take 5~6 hours, or more, then settle down to a low level of charging, to maintain it. I’m using a CTEK, Nocco is currently popular as well.
     
    #9 Mendel Leisk, Mar 17, 2024
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