All warning lights on, high battery voltage

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by cra205, May 22, 2023.

  1. cra205

    cra205 New Member

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    I have a 2011 base Prius. It is not recognizing the smart key but if I hold the key to the start button it will start. Once it starts, it runs fine but all the warning lights stay illuminated and the message center toggles through the various warnings (maintenance required, check hybrid system etc.) I suspected I have a a bad 12v battery as what I have read here indicates that can cause strange electrical issues. When I check the batter voltage at the fuse box with the car off, it’s almost 17v, car running is 21v. Has anyone else seen this? I am still thinking it could be the battery, but wanted to ask before spending $250 on a hunch. Thanks in advance for your input!
     
    #1 cra205, May 22, 2023
  2. CR94

    CR94 Senior Member

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    Those are strangely high voltages. Check with a different meter to see whether you get the same values.
     
    #2 CR94, May 25, 2023
  3. Grit

    Grit Senior Member

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    Shocked that all 12v components are still working running on 21v measured with car on ready :eek:
     
    #3 Grit, May 25, 2023
  4. bisco

    bisco cookie crumbler

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    usually, that's a dead fob battery, so start there.

    i suspect something is wrong with your multimeter, or it's on the wrong setting
     
    #4 bisco, May 26, 2023
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  5. CR94

    CR94 Senior Member

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    ...Or the multimeter's battery is failing. I have a cheap multimeter that will appear to function, but shows falsely high voltages if its internal battery voltage drops too low.
     
    #5 CR94, May 26, 2023
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