Horn & Hazard Flashers run amuck

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by CR94, Jan 3, 2025.

  1. CR94

    CR94 Senior Member

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    Yesterday as soon as I opened the driver's door upon returning from a store stop, the horn began pulsed beeping. The turn signal indicators in the instrument panel were blinking in synchronization with the beeps. When I pressed the hazard-flasher switch button two times, the blinking and honking (blissfully!) ceased. Everything was seemingly back to normal the rest of my trip home. I'd like to know what was going on, and how to be sure this doesn't happen again. Has this happened to anybody else's 3rd generation Prius?
    To answer a few likely questions:
    1. The car does not have an antitheft system.
    2. No other weird electrical symptoms, ever.
    3. The door had not been locked before I opened it.
    4. I didn't look to see whether the turn signals bulbs were actually flashing along with the indicator lights.
    5. Frequency of the beeps and blinks seemed about normal for the flasher system, but I'm not certain it was.
    6. No known rainwater leaks into the interior.
    7. Nothing spilled on the switchgear near the hazard-flasher switch---or anything else.

    Here's a thread about hazards being affected by abs module problems. I don't know whether it's related to my car's .
    ABS Module Failure After 17V718000 Recall | PriusChat So far, I haven't found any threads that seem more closely related, but one may be out there.

    Thanks for any clues!
     
  2. ChapmanF

    ChapmanF Senior Member

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    No added antitheft system, maybe, but there's some basic functionality built into the car.

    The synchronized flashing and honking sounds exactly like what that does if it thinks the door has been opened without unlocking first with the fob or mechanical key.

    I assume you think you did unlock first, using the fob or the mechanical key, so it might be a question of why the car thought you hadn't.

    The reasons can be various. In my gen 1, I once replaced a door lock actuator with a cheaper one from eBay that turned out to have been built without the contacts inside that signal when the mechanical key is used to unlock. Discovered that, of course, when the car started honking and flashing any time I opened the door that way.
     
  3. rjparker

    rjparker Tu Humilde Sirviente

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    IMG_7117.jpeg IMG_7118.jpeg
     
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  4. xliderider

    xliderider Senior Member

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    Might be unrelated, but how old is your 12V auxiliary battery?

    Prii are known to have all sorts of weird things going on when the battery is dying.

    SM-G781V ?
     
  5. CR94

    CR94 Senior Member

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    Thanks for the quick reply. I admit I wasn't aware the car has that capability to sound off if the door is unlocked by a non-approved method. I do know about the "Panic Mode" feature (re rjparker's post), although I've never tried it, and doubt that I accidentally pressed it this time. No, I didn't "unlock first" by any method, simply because I knew I hadn't locked the doors when I left the car (as stated in my original post). Merely opening a door that wasn't locked in the first place shouldn't have caused the system to panic. Perhaps some faulty sensor or switch in the door "thought" it was locked when it was not? That wouldn't explain the beeping stopping when I pressed the hazard-flasher switch.

    If this happens again, I'll try pressing a fob button to see if that stops the beeping. If so, I'll stop worrying that it might be a more serious problem.
     
  6. CR94

    CR94 Senior Member

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    Installed January 2024.
    The fob battery is more iffy.
     
  7. xliderider

    xliderider Senior Member

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    Fob batteries last about 2 years.

    SM-G781V ?