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Prius 12V Battery went dead in 20 hours, Fob key won't unlock door

Discussion in 'Gen 4 Prius Main Forum' started by sgpriusdriver, Mar 14, 2017.

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  1. sgpriusdriver

    sgpriusdriver New Member

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    I last used my prius gen4 at around 9pm(+8 GMT) Monday. At Tuesday 5pm (+8 GMT), when I went to the prius, the 12v battery had already died, thus the keyless entry won't work. Tried to use the mechanical key located in the fob but it won't unlock the door no matter how much I twisted.

    Now had to tow the car back to the workshop.

    Anyone knows why the mechanical key won't work?
     
  2. jerrymildred

    jerrymildred Senior Member

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    Have you used the key before? I wonder if it's the wrong key. Seems unlikely with a car I assume you bought new, but otherwise, it should work if you turn it the right way.
     
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  3. pakitt

    pakitt Senior Member

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    The user's manual says how you need to use the key inside the FOB to mechanically open the driver's door. Including which direction.
    Question is though: how did the 12V battery drain so fast in a brand new car?
     
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  4. alanclarkeau

    alanclarkeau Senior Member

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    The mechanical key will only go one way round - but then I think it'll only go in one way. There is little leverage because it hasn't got a Bow, only a Shoulder to try to hold, and takes a little effort to turn, but not excessive.
     
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  5. jerrymildred

    jerrymildred Senior Member

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    Interesting! I wonder if it's a generational or a market difference. Our U.S. generation 2 & 3 keys go in either way and turn either way. The wrong way simply does nothing except make a little noise (assuming the 12V battery isn't dead ;)).
     
  6. alanclarkeau

    alanclarkeau Senior Member

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    It's pouring rain outside and 11pm - I'll double check in the morning upload_2017-3-14_23-17-57.png .
     
  7. bisco

    bisco cookie crumbler

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    12v on a '16 is more robust, this is unfortunate to hear.
     
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  8. kithmo

    kithmo Couch Potato

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    Yes I agree, since the Gen 4 shuts everything off after a while (30mins ?) unless it's in ready mode. o_O
     
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  9. Prodigyplace

    Prodigyplace Senior Member

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    In Ready mode it would charger from the traction battery & start the engine as needed, wouldn't it?
     
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  10. kithmo

    kithmo Couch Potato

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    Yes, so again it shouldn't go flat. AFAIK the only thing you can leave on are the parking lights, maybe that's what the OP did ?
     
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  11. alanclarkeau

    alanclarkeau Senior Member

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    Yes - mine turns the hatch light off after 20 mins - I was there when it did it once. Never tried the parking lights - on one of my cars, FORD or KIA?? they would turn off after 20 mins or so too.
     
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  12. bisco

    bisco cookie crumbler

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    what if you leave a door open, or turn on a map light with the switch?
     
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  13. alanclarkeau

    alanclarkeau Senior Member

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    Just checked - it only goes in one way, just won't slot in the channel the other way. Turn one way to lock, other way to unlock.
     
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  14. alanclarkeau

    alanclarkeau Senior Member

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    Hatch light turns off after 20 mins - as does the light over the mirror which my Mum keeps leaving on.
     
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  15. bisco

    bisco cookie crumbler

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    this is a new feature, and a long time coming. would have saved a lot of batteries over the past 12 years.
     
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  16. alanclarkeau

    alanclarkeau Senior Member

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    That's odd - I thought car makers have done this for more than a decade - my 2006 KIA RIO did.
     
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  17. bisco

    bisco cookie crumbler

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    for the last 12 years, we have been speculating that there was something special about the prius, that didn't allow toyota to use this feature.

    similar to, why does toyota allow the car to be driven without the fob in it? i suppose that will come in time.
     
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  18. Prodigyplace

    Prodigyplace Senior Member

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    Perhaps part ownership in a battery company?
     
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  19. bisco

    bisco cookie crumbler

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    i hope so. would be crazy to build hybrids and not.
     
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  20. sgpriusdriver

    sgpriusdriver New Member

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    I have used the manual keys before and they do unlock previously.

    According to my workshop, the 12V battery has failed. It's under Toyota warranty. So it has to be replaced.

    To note Prius will beep alarm if you lock door without turning off any of the front lights.
    Also I haven't left anything powered on when I left, I have checked before I went off.
    If you are in ready mode, toyota won't allow you to lock the car doors from outside.