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Voltage Bouncing all over the place

Discussion in '2nd Gen Tundras (2007-2013)' started by SkipperPete, May 4, 2021.

  1. May 4, 2021 at 3:20 AM
    #1
    SkipperPete

    SkipperPete [OP] New Member

    Joined:
    May 23, 2020
    Member:
    #46997
    Messages:
    29
    Gender:
    Male
    First Name:
    Pete
    Catonsville, MD
    Vehicle:
    2012 Silver Tundra Crewmax
    Hey fellers,

    My voltage is constantly bouncing all around. It never reaches the mid-mark, always below... Even while throttling up or driving. It's also never steady. It's always fluctuating back and forth. My head unit is reading it anywhere between 12.7 - 13.2. I read through some posts and found most people float between 13.0 - 13.5. Here are some other symptoms that I've noticed. Whenever the headlights are on and I do anything else (tap the brakes, use blinker, turn on interior light) the headlights will dim for a split second. But even as I sit with my foot on the brake, I can see the headlights kinda flickering from bright to dim every couple seconds. I've also recently noticed my interior lights will flicker slightly, as well as the light behind the odometer. This is driving me nuts! The previous owner had a whole sound system put in with a powered sub and an amplifier under the seat. This all seems to be professionally installed.
    Should I be concerned? I'm not sure if it's the alternator or a battery or what. I've never had any other relatable issues! Thanks for any help!
    Pete

    Screenshot_20210504-062014_Gallery.jpg
     
  2. May 4, 2021 at 3:26 AM
    #2
    timsp8

    timsp8 Member

    Joined:
    May 11, 2018
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    #15231
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    Tim
    NY
    Vehicle:
    2018 Tundra Limited Crewmax
    You can go to just about any auto parts store to get you battery checked. I’d start with that since it’s free.
     
    SkipperPete [OP] likes this.
  3. May 4, 2021 at 4:51 AM
    #3
    Bakershack

    Bakershack Critical of Noncritical Thinkers

    Joined:
    May 20, 2020
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    #46846
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    Kelly
    Spanish Fort, AL
    Vehicle:
    2020 SSM 1794 4x4
    If it happens while running it is much more likely to be the alternator than the battery. It could also be cause by loose connections or something grounding out. Of those, I would hope for a bad alternator. Much easier to diagnose and repair.
     
    SkipperPete [OP] likes this.
  4. May 4, 2021 at 10:13 AM
    #4
    audiowize

    audiowize New Member

    Joined:
    Dec 11, 2020
    Member:
    #56016
    Messages:
    343
    Gender:
    Male
    First Name:
    Paul B.
    Vehicle:
    2008 Tundra SR-5 4x4 5.7
    You could very easily just have a loose battery cable. Always start with what's free to check.
     
    SkipperPete [OP] and Bakershack like this.
  5. May 5, 2021 at 4:34 AM
    #5
    jbrnigan

    jbrnigan New Member

    Joined:
    Jul 3, 2016
    Member:
    #3752
    Messages:
    33
    Gender:
    Male
    Midwest
    Vehicle:
    2007, 5.7L, 4x4, Crewmax,
    The voltage on my '07, measured at the ECU through the OBD port, runs from 13.5 up to 13.8 or so after the initial start up.
     
    SkipperPete [OP] likes this.

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