2011 Prius key repeatedly runs down key battery

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Bill Forest, Apr 30, 2017.

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  1. Bill Forest

    Bill Forest Junior Member

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    Vehicle:
    2011 Prius
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    III
    2011 Prius 3.
    My daughter's key fob quit working to unlock doors, etc. She could start the car if she held the key up to the power button. We figured it was a dead battery in the fob, so we replaced it. That worked for one day. Thinking we had gotten a bad battery, we replaced the battery again. Again, it worked for about a day. Replaced the battery a third time--which also worked for about a day. Each time I replaced the battery, the one I replaced was no longer at 3 Volts--it was around 2 Volts.
    She does not keep her keep with her phone. She generally keeps the key alone in her pants pocket.
    I assume that something is draining the battery.
    Any suggestions?
    Thanks!
     
    #1 Bill Forest, Apr 30, 2017
  2. bisco

    bisco cookie crumbler

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    welcome!
    how about the other fob? it could be a stuck button.
     
    #2 bisco, Apr 30, 2017
  3. xliderider

    xliderider Senior Member

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    +1 on the stuck button. Make sure that the buttons are free when putting the fob shell halves together. A stuck button will cause the fob to continuously transmit and run the battery down.
     
    #3 xliderider, Apr 30, 2017
  4. Bill Forest

    Bill Forest Junior Member

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    The other fob works perfectly.
    As far as stuck buttons, all of them feel normal--that is--I can push each one and hear the clicking sound. They don't feel stuck. Is it possible they are stuck in a way that I cannot tell?
     
    #4 Bill Forest, May 1, 2017
  5. bisco

    bisco cookie crumbler

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    not sure. the red light should go on and off when you press a button. you can try prying the edges of each button with an exacto knife.
     
    #5 bisco, May 1, 2017
  6. xliderider

    xliderider Senior Member

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    Maybe a long shot, but did you put the battery in observing the right orientation/polarity?
     
    #6 xliderider, May 1, 2017
  7. Dyjital

    Dyjital Member

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    Asking the obvious here:
    Cheap battery or name brand?

    And a 3V battery should be a little over 3v to start with. A 1.5v is actually 1.65v. I'd go measure my new energizer batteries for our fobs but I'm lazy.
     
    #7 Dyjital, May 3, 2017
  8. Bill Forest

    Bill Forest Junior Member

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    Thanks for all of the thoughts and suggestions. I tried one new duracell batteries and two "generics" from BatteriesPlus. All of them ran down within a day. I tested them at 3+Volts prior to installing. All of them are around 2.2 after 24 hours. All of them were installed with correct polarity.
    The red light only comes on when I push the buttons down, and the buttons do not feel in the stuck position.
    I took the fob apart as far as I could--so that I could see if there was a bent contact inside. I do not think that is the case.
    Does anyone have any other thoughts?
    Has anyone ever seen a fob "go bad" so that this happens?
    If I have to replace the fob, from my cursory investigation, it looks like over $300 to purchase and program. Is that really the case? I surely hope not! Thanks for all of your help. I appreciate it.
     
    #8 Bill Forest, May 3, 2017
  9. Sam Spade

    Sam Spade Senior Member

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    Yes. Or some other electrical fault has developed.
    Sounds to me like that FOB needs to be replaced.
    Locksmiths often can do it MUCH cheaper than a dealer.
     
    #9 Sam Spade, May 3, 2017
  10. Maranatha

    Maranatha New Member

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    I lost my original key fob, and even though I had a spare, I wanted to replace the lost one. The locksmith disabled the original, and programmed the third one. Ever since then, whenever using either fob, I'm getting a low key battery light on the dash. We've replaced the batteries, but it still happens. Any ideas why this happens?
     
    #10 Maranatha, Mar 28, 2020
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