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Car alarm randomly going off?!?

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by Gobbletown, Jul 13, 2017.

  1. Gobbletown

    Gobbletown Junior Member

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    2017 Prius Prime
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    Over the past few weeks I've been notified by my staff that the alarm on my Prime is going off at odd times and without provocation throughout the day...

    Knowns:
    -Keys not in pocket; panic not being pressed
    -No one is physically setting it off
    -Carista OBD2 says 12 V battery "poor charge" (or something to that effect) but 2 different dealers both report no problems with 12 V
    -Dealer found fresh varmint nest in engine bay under the plastic cover for the top of the motor but no damage seen at 10K mile checkup
    -Dealer found no problems with inspection or diagnostics at 10K
    -After alarm my navigation screen is oriented differently than usual (I like pointing 'up' on the screen instead of an ordinal direction)
    -After alarm all radio stations seem to reset to 88.7
    -Only happening in am after drive to work both with and without an overnight charge and work is well outside the 25-30 miles to have any left on the traction battery other than the reserves

    Hypotheses
    -Mouse chewed through something, but alarm is predictably going off in the am around 9-10 and one day was every 30min to the second which wouldn't seem to happen with random frayed wires
    -12V battery is kaput and when the charge dwindles the car freaks out and alarms, hot climate and heat seems to worsen; and Toyota doesn't want to pony up for a replacement 12V despite having evidence of an error code (which has since been reset and isn't displayed with recent Carista checks)
    -Some accidental 'valet' mode was entered and this is a purposeful alert I'm not aware of

    Would love to fix because staff is getting a headache with the morning wake up calls...

    Thanks!


    iPhone ?
     
    #1 Gobbletown, Jul 13, 2017
  2. bisco

    bisco cookie crumbler

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    you need to check the 12v with a volt meter. is the horn honking, or did you purchase an alarm?
     
    #2 bisco, Jul 13, 2017
  3. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    ..........-Dealer found fresh varmint nest in engine bay under the plastic cover for the top of the motor but no damage seen at 10K mile checkup
    ..........-After alarm all radio stations seem to reset to 88.7

    Hmmmm...

    You have a nearly-chewed-thru wire or insulator somewhere near where the varmints were hanging out, and it's causing a drain on the aux battery.

    Good News: Once you find it, it's an easy fix!

    Bad news: Finding it will be a really tough and potentially expensive problem - and I'll betcha my CPO coin that 'rodent infestation' is one of the 142,600 caveats in the new car warranty.

    You can rule out the 'defective aux battery' by simply replacing it.
    Most warranties do not cover these batteries since most of the time they go bad due to abuse or neglect by the customer.
    Back in the day....(2010) since Toyota didn't have a proper voltage management system on their cars (like my GM does) people were depleting their 12v batteries by leaving dome lights on.
    I'm sure this has been fixed by now, but I'm also sure that mieces in the engine room would be considered as customer neglect.
    (get a cat)

    If I'm wrong then you will have spent about $200 for a replacement battery that was the original root cause of all of your troubles.
    You can try to go after the dealer if this is the case, but you might want to make sure that the battery is the problem first....

    If I'm right, then after you replace the battery.....and after some time passes....the problem will re-appear, and then you can make the dealer prove that it's not a defective component in the wiring, and the only way that they can do that is to find the chewed wire for you.

    Good Luck.
     
    #3 ETC(SS), Jul 13, 2017
    Last edited: Jul 13, 2017
  4. Gobbletown

    Gobbletown Junior Member

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    Thanks

    Alarm was original/factory option not aftermarket. 3x dealer visit with a check of the 12v has been "no problem" or "good charge/battery".

    Would they not tell me (if they aren't going to replace it anyway) if it was bad?


    iPhone ?
     
    #4 Gobbletown, Jul 13, 2017
  5. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    Don't forget that vermin damage to wiring is typically covered by comprehensive insurance. Found out about that the hard way after rats or mice chomped up the wiring on my son's car, and we had already paid big $$ to fix it.
     
    #5 CharlesH, Jul 15, 2017
    Mendel Leisk likes this.
  6. 'LectroFuel

    'LectroFuel Senior Member

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    Has Toyota found an alternative to the soy-covered wires yet?
     
    #6 'LectroFuel, Jul 17, 2017
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