Viewing 12v battery voltage from menus

Discussion in 'Gen 4 Prius Technical Discussion' started by fsu23phd, Sep 20, 2021.

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  1. fsu23phd

    fsu23phd Active Member

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    Hello, I have a 2016 (two eco) showing signs of low 12 v battery. This is my 3rd prius. On my old 2005 and 2010s, I could check the battery health from a top secret hidden menu.

    I can't figure out how to find the top secret menu for my 2016 on Google. Does anyone know how to do this? Also, what at what voltage should I replace the 12v battery? Thanks!
     
    #1 fsu23phd, Sep 20, 2021
  2. alanclarkeau

    alanclarkeau Senior Member

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    This might help -
     
    #2 alanclarkeau, Sep 20, 2021
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  3. sam spade 2

    sam spade 2 Senior Member

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    You can't trust the onboard readings to diagnose the health of a 12 V battery.

    Have it tested at a battery store, auto parts store or dealership.......usually for free.
     
    #3 sam spade 2, Sep 20, 2021
  4. fsu23phd

    fsu23phd Active Member

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    Ok, I figured it out. Start to accessory mode (don't hold the break). Then hold the car button (near the radio in the two eco) and turn the lights on and off 3 times. The battery health is under Vehicle Signal. Looks like I need a new battery.
     

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    #4 fsu23phd, Sep 20, 2021
  5. ChapmanF

    ChapmanF Senior Member

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    In the earlier generations, the top secret instructions for getting to the Vehicle Signal Check screen were hidden away in the *cough*repair manual*cough*, very cleverly where no one would think to look. (more info)

    I don't know about the 2016 for sure, but it's possible the instructions could be in the *cough*same place*cough*.
     
    #5 ChapmanF, Sep 20, 2021
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    I wouldn’t rely on the car displays, even to give accurate voltage, never mind battery health.
     
    #6 Mendel Leisk, Sep 20, 2021
  7. FuelMiser

    FuelMiser Senior Member

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    what's "the car button" you speak of? post a pic
     
    #7 FuelMiser, Sep 21, 2021
  8. sam spade 2

    sam spade 2 Senior Member

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    Probably.
    It is usually pretty easy to verify that a battery is really BAD.
    Verifying that it is "good" often is a bit trickier.
     
    #8 sam spade 2, Sep 21, 2021
  9. burrito

    burrito Active Member

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    It's literally a button that says "CAR" on it. The buttons are different based on what features you have, so you won't have that button if you do have the factory navigation system installed.
     
    #9 burrito, Sep 21, 2021
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