1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Continuous tone / alarm after start

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Win79, Feb 14, 2020.

  1. Win79

    Win79 New Member

    Joined:
    Feb 14, 2020
    3
    0
    0
    Location:
    Sudbury,MA
    Vehicle:
    2010 Prius
    Model:
    III
    I have a 2010 Prius that makes a continuous high-pitched tone or alarm sound after it starts up. There are no indicator lights about a problem, and the car seems to drive fine. I took it to a local garage, where they ran diagnostics but did not find anything, and they're rather mystified. It may or may not be relevant that the 12V battery was recently changed, although it did not happen until at least several days later.

    Someone posted with a similar description on Reddit. The video they posted sounds like the what I hear:

    Any thoughts? Thanks!
     
    #1 Win79, Feb 14, 2020
  2. dig4dirt

    dig4dirt MoonGlow

    Joined:
    Apr 6, 2012
    1,150
    741
    0
    Location:
    Lancaster Co PA
    Vehicle:
    2014 Prius c
    Model:
    Two
    I do not get any audio from the video you posted.

    Did you try to disconnect the 12v and reconnect to see if it helps?
     
    #2 dig4dirt, Feb 16, 2020
  3. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,784
    48,988
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Door/hatch not shut tight
     
    #3 bisco, Feb 16, 2020
  4. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,318
    15,107
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    From your description (not by listening), a continuous high pitched tone makes me think of the alarm for the system that keeps operating pressure for the brakes.

    Ordinarily it would also light a brake warning light on the dash. I wouldn't expect the tone and no light, unless there's a problem in the warning light circuit (unlikely, not impossible).

    Has anybody done a health-check scan with Techstream? Sometimes third-party scanners will miss something.

    It would be possible to have nothing more going on than a problem in the circuit feeding the high pitched alarm buzzer itself.
     
    #4 ChapmanF, Feb 16, 2020
  5. Win79

    Win79 New Member

    Joined:
    Feb 14, 2020
    3
    0
    0
    Location:
    Sudbury,MA
    Vehicle:
    2010 Prius
    Model:
    III
    Thanks for the replies. @digfordirt, I have disconnected the 12V twice, once briefly. The problem went away for a little bit and then returned. On the second time, based on another suggestion, I disconnected the 12V and held the cables together for a couple minutes to try discharge any capacitance in the system, but that didn't work. The sound is loudest under the dashboard on the driver's side.

    Also, the video starts off with the audio muted by default, at least when I first encountered it.

    @ChapmanF I don't know what diagnostic gear the local garage has, but at this point it's going to a dealer to look at. Not looking forward to a 20-minute drive with that going on!
     
    #5 Win79, Feb 16, 2020
  6. Win79

    Win79 New Member

    Joined:
    Feb 14, 2020
    3
    0
    0
    Location:
    Sudbury,MA
    Vehicle:
    2010 Prius
    Model:
    III
    According to the dealer, it was the Skid Control ECU / ABS Actuator, which had to be replaced (and is not cheap!). But at least it's quiet now.
     
    #6 Win79, Feb 19, 2020
  7. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,318
    15,107
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Did they report any of the trouble codes to you?
     
    #7 ChapmanF, Feb 19, 2020
(You must log in or sign up to post here.)