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Signs of a dying 12 volt battery

Discussion in 'Gen 3 Prius Main Forum' started by write2toonces, Apr 4, 2019.

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  1. write2toonces

    write2toonces New Member

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    Vehicle:
    2010 Prius
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    Four
    One month before the 12V battery died, I noticed the "Ready" light came on slower than usual after pressing the Start button.

    A week before the battery died, one of the front HID headlights (aftermarket) would turn off when the engine is off. I thought that was odd, but then it makes sense that the ballast needs power to start up the xenon bulbs.

    On a cold morning, while parked on an incline, I got the P-lock malfunction message: "P lock malfunction: Please park on a level surface and ...". The car would not shift out of Park. After a few tries to restart, the screen gave out completely. I read messages on this board and 1) jump-started the car by connecting through the (+) terminal under the fuse box, 2) drove directly to the nearest Autozone and had the original 9 years old battery tested, and 3) bought a new replacement battery for $232. That solved all those problems from earlier.

    For a high-tech car, I'm surprised that Toyota didn't put in a warning message when the 12V battery is at the end of its life. That P-lock malfunction message is lame and confusing. Thank you for those who posted answers to the P-lock malfunction issue. I hope this post will help others too.
     
    #1 write2toonces, Apr 4, 2019
    Prieth and bisco like this.
  2. bisco

    bisco cookie crumbler

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    yep
     
    #2 bisco, Apr 5, 2019
  3. Salamander_King

    Salamander_King Senior Member

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    Glad you solved the problem, but wow that's expensive 12v battery. I owned Gen3 but not long enough to needing the 12v replaced.

    That said, your "original 9 years old battery" was probably giving you plenty of warning beforehand I think, you just did not notice them. Although I don't know of any car that can give accurate prediction of when 12 v battery dies. I've had plenty of dead battery incident happened on my other cars but not on Prius yet. They usually gives off many warming symptoms like dim head lights, engine not turning over, etc. when the battery get old. Maybe with Prius, it is bit more difficult to spot the difference.
     
    #3 Salamander_King, Apr 5, 2019
    Last edited: Apr 5, 2019
  4. Grit

    Grit Senior Member

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    2 many variables to predict when battery will kick the bucket. Even test loads devices are inaccurate.

    My friends 12v battery cracked at the base of positive post, Car computer never threw a CEL or low bat light.
     
    #4 Grit, Apr 5, 2019
    Raytheeagle likes this.
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