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Reboot the system? Car Completely Dead but Comes Back to Life

Discussion in 'Gen 2 Prius Main Forum' started by Michael Crestohl, Dec 20, 2022.

  1. Michael Crestohl

    Michael Crestohl Junior Member

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    This one is strange…….. I go to open my car (SKS is on). Open the door and the horn starts honking, light flash then everything goes dead. Then somehow later it comes back to life again,
    Last week I took it for an oil change. Technician who drove it out of the shop told me the display was not on. We went out to look at it, totally dead. The suddenly the system came back to life, it started and I drove it home, no peoblem, about 20 miles. That was five days ago. Today I went out to start it up and, horns blowing, etc, now completely dead.

    Anyone have experience with this?

    Holiday Seasons Greetings,

    Michael Crestohl
     
    #1 Michael Crestohl, Dec 20, 2022
  2. sam spade 2

    sam spade 2 Senior Member

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    That kind of situation is not all that strange.
    You likely have an intermittent open in the main 12 V battery supply somewhere.
    If the battery is more than 5 years old, just replace it and fully charge the new one.
    There could be a connection going bad INSIDE the battery.

    The other suspect is the connections at both ends of both main battery cables.
    The negative one that goes to the body/frame is often a problem.

    With all of those vehicles and being a HAM, you do have a multi-meter......right ??
     
    #2 sam spade 2, Dec 20, 2022
  3. Michael Crestohl

    Michael Crestohl Junior Member

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    The battery is supposedly new. And yes, I do have a Voltmeter. Thanks for the heads up. But why do the horns start blowing when I opened the door?
     
    #3 Michael Crestohl, Dec 20, 2022
  4. edthefox5

    edthefox5 Senior Member

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    The dash dead is very common. And sounds like also the 12 volt battery is bad too.

    The dash lcd panel has failed. The dash is called the COMBO METER on this site.
    It must be replaced. You can do it yourself if your handy.
    Last time I looked it was $100 for a new combo with your core. We all use Matt@Texashybrid for a new combo.

    Here's some Combo meter info Matts contact is in there:

    https://priuschat.com/search/364067094/?q=combo+meter&t=post&o=relevance&c[node]=12+54

    Go on youtube search COMBO METER first video is a great one its the R & R for that meter.
     
    #4 edthefox5, Dec 20, 2022
  5. dolj

    dolj Senior Member

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    It will always do this when the alarm loses power when it is set and then subsequently the power is reconnected. It is a security thing.

    I would suspect that one or both of the terminals and/or the ground strap at the body is loose would be the reason for the loss of power.
     
    #5 dolj, Dec 20, 2022
    Last edited: Dec 21, 2022
  6. Michael Crestohl

    Michael Crestohl Junior Member

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    Actually the combo meter doesn’t need to be replaced. The problem is likely caused by a 100uF 16 Volt electrolytic capacitor that is called C3 that should be replaced by a 220uF 16Volt electrolytic. Once the display has been removed it is a pretty easy fix for someone with basic soldering skills. But removing the dash panels is a PITA especially without a warm garage in December in which to work. I don’t think this is not causing the,problem. I will take a close look at the 12Volt wiring first. Even though the battery is supposed to be new it is a cheap POS. ( came with the car) and I may replace it with an Optima Yellow Top AGM battery and be done with it.
     
    #6 Michael Crestohl, Dec 21, 2022
    Last edited: Dec 21, 2022
  7. dolj

    dolj Senior Member

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    These Optimas are not what they once were (quality and reliability) and are (now) considerably more expensive than the OEM.

    Just get an OEM TrueStart and be done with it.

    You might not even need a new battery though if the terminal connections are clean and tight. Check those first and charge it up if necessary.
     
    #7 dolj, Dec 21, 2022
    Last edited: Dec 21, 2022
  8. sam spade 2

    sam spade 2 Senior Member

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    Likely that nobody can answer that last question.
    (Edit) But I see that someone HAS. And the explanation makes perfect sense.

    Low supply voltage can cause computers to do all kinds of strange things.
    In this case, something is triggering the security alarm.
    Note: New batteries can sometimes go bad too.
     
    #8 sam spade 2, Dec 21, 2022
    Last edited: Dec 21, 2022
  9. sam spade 2

    sam spade 2 Senior Member

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    BAD advice, Ed.
    One should not be chasing the display problem until the basic power problem is fixed.
     
    #9 sam spade 2, Dec 21, 2022
    mr_guy_mann likes this.
  10. mr_guy_mann

    mr_guy_mann Senior Member

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    An advocate for testing- yeah!

    Posted via the PriusChat mobile app.
     
    #10 mr_guy_mann, Dec 21, 2022
  11. sam spade 2

    sam spade 2 Senior Member

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    And an advocate of keeping things in perspective and not overlooking the obvious.
    Like not overlooking the knife sticking in your foot when trying to figure out why you are limping. :eek:
    :)
     
    #11 sam spade 2, Dec 21, 2022
  12. Skibob

    Skibob Senior Member

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    Definitely check the 12v battery connections, especially the grounding bolt to the chassis for tightness and corrosion.
     
    #12 Skibob, Dec 22, 2022
  13. TMR-JWAP

    TMR-JWAP Senior Member

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    replacing a cheap one with a not cheap one may not be the answer you're looking for.

    I would say go your local NAPA and get their "Legend" version of the Prius 12v battery, or OEM.
     
    #13 TMR-JWAP, Dec 22, 2022
  14. Michael Crestohl

    Michael Crestohl Junior Member

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    This seems to be the source of the problem…….. Toyota used a single 10mm screw attached to a threaded hole in the body for the electrical ground. I removed the bolt and used my trusty Dremel and wire wheel toclean off the metal areas and put it back together with a bit of conductive grease. I also cleaned the battery terminals and positive battery clamp so it appears that all is well. Thanks everybody for your input.
    Merry Chrismas, Happy Chanukah, or whatever your pleasure.
    Michael Crestohl
     
    #14 Michael Crestohl, Dec 22, 2022
    Last edited: Dec 23, 2022
    TheRedRocker likes this.
  15. sam spade 2

    sam spade 2 Senior Member

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    Actual conductive grease is not very common.
    Most dielectric grease is NOT conductive but some is mis-labeled.
    And it seems that a really LOT of people don't understand that.
     
    #15 sam spade 2, Dec 22, 2022
  16. Michael Crestohl

    Michael Crestohl Junior Member

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    Yes, there is a big difference between the two substances. Dielectric grease is a non-conductive waterproof substance used to protect electrical connections from corrosion and dirt. On the other hand conductive grease, aka electrician’s grease can be used for electrical connections in applications like RV house battery terminals. It is not particularly difficult to find.
     
    #16 Michael Crestohl, Dec 23, 2022
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