Can the 12v battery cause weird dash lights?

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by GlitterPsycho, Oct 5, 2022.

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  1. GlitterPsycho

    GlitterPsycho New Member

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    Hi! My 2013 Prius v is having weird issues. When driving home the other day, all of the brake lights lit up when i wasn’t even using the brakes. It was the red brake light (the emergency brake wasn’t on), the ABS light, the PCS light started flashing, the car on the derby road, and the circle with the !. The brakes felt weird but were still working.
    i had it towed to a brake shop and they couldn’t figure it out. They told me to drive it to the dealer and that the check engine light came on while they were testing. That light was not on before.

    i got the car back and will take it tomorrow but the dealer sucks here and i wanted to get an idea of what to expect. Can the battery cause this? None of the brake lights are on now and he didn’t do anything to the brakes so that makes no sense to me. My dad suggested maybe it’s the 12v battery after seeing that the brake lights can get triggered by the battery? Can the check engine light too? Thanks y’all!!!!!!
     
    #1 GlitterPsycho, Oct 5, 2022
  2. xliderider

    xliderider Senior Member

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    What year (NVM it's a 2013) and how many miles on the odometer?

    How old is your 12v battery?

    You can get your codes read at almost all nationwide auto parts stores. Once you get the codes, you can look them up.

    It could be the 12v battery, but it could also be more serious, like the brake booster/accumulator.

    Posted via the PriusChat mobile app.
     
    #2 xliderider, Oct 5, 2022
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  3. rjparker

    rjparker Tu Humilde Sirviente

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    Hopefully its less than ten years old and under 150,000 miles. If so the increasingly common $2,500 brake booster failure would be covered.
     
    #3 rjparker, Oct 5, 2022
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  4. ChapmanF

    ChapmanF Senior Member

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    The dash lights generally indicate there are trouble codes you can read from the car. and a few of the different ECUs in the car do have a few trouble codes that are meant to tell you about low voltage issues. So those are completely legitimate examples of how a battery issue can give you dash lights and codes.

    Beyond those cases, there are some other issues where very low battery voltage might have led to a malfunction causing a trouble code to be set. If that's what happened, generally you'd expect that the codes you have will include at least one of the "hey, did you see how low this voltage is?" codes as well.

    Further beyond that, there's a school of thought where pretty much anything can be pinned on the 12 volt battery with some kind of handwavey explanation, if finding the real explanation just sounds like more work than somebody wants to put in. Enough said about that.

    To figure out what's going on with your car, the main thing is to find out what trouble codes it's reporting. Whether those codes are or aren't the ones that might pertain to the battery, then we'll know.

    A good scan tool is the easiest way to get the codes, but for some systems in the car it's not the only way. Something very convenient about the brake system is when any of those lights (brake, ABS, VSC, ((!)) come on, you can get the code just by putting a short piece of wire between the Tc and CG terminals of the car's diagnostic port, and counting the blinks of the dash lights. You can search for threads here with more details on that. Then you have the brake system codes, no scan tool needed.

    If you see those lights again, that's what I'd recommend doing. You can post the codes here.
     
    #4 ChapmanF, Oct 5, 2022
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  5. bisco

    bisco cookie crumbler

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    maybe yes, maybe no
     
    #5 bisco, Oct 5, 2022
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  6. Air_Boss

    Air_Boss Senior Member

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    I have seen a loose OBD2 reader plug light up the dash and disable regenerative braking among other factors.
     
    #6 Air_Boss, Oct 5, 2022
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  7. GlitterPsycho

    GlitterPsycho New Member

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    It’s a 2013 and has like 220k miles. I replaced the engine last year but i don’t think i have done the battery yet
     
    #7 GlitterPsycho, Oct 5, 2022
  8. GlitterPsycho

    GlitterPsycho New Member

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    it’s definitely over that. Crap. It’s got like 223k ion it

    thank you so much! That doesn’t sound too hard

    hahahahaha thanks! I seriously needed that laugh so it’s much appreciated. It’s been a heck of a week

    thanks! Is that something i can check at home?
     
    #8 GlitterPsycho, Oct 5, 2022
    Last edited by a moderator: Oct 6, 2022
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  9. Air_Boss

    Air_Boss Senior Member

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    Shut the car down, remove the OBD2 reader/module from the port, and start the car.
     
    #9 Air_Boss, Oct 6, 2022
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