Slight but annoying whine noise when operating brake pedal

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by matherm, Dec 11, 2009.

  1. SalixIncendium

    SalixIncendium Tree Hugging Environmentalist Wacko

    Joined:
    Mar 26, 2013
    155
    68
    0
    Location:
    Dayton, OH
    Vehicle:
    2013 Prius
    Model:
    Three
    The high pitched noise at the very beginning of the video is the exact noise that I described earlier ITT that I hear when I glide (though it's much more pronounced when I glide). I agree with Reedja that it's likely the inverter. I, like Reedja, don't recall ever hearing it when the car is powered down, so I'm not sure if that's normal.
     
  2. p00kienrayray

    p00kienrayray Active Member

    Joined:
    Mar 14, 2012
    720
    135
    0
    Location:
    Long Beach, CA
    Vehicle:
    2013 Prius
    Model:
    Three
    Had a Toyota technician friend look at it yesterday and let him drive it. He said it is most likely the inverter, though he is not sure why it comes on while car is off either. He said just drive it and if it gets any worse or if I just can't stand it anymore within warranty period, then take it in. Thanks to everyone for the input :)
     
  3. El Dobro

    El Dobro A Member

    Joined:
    Jul 12, 2011
    6,346
    2,787
    1
    Location:
    NJ
    Vehicle:
    2014 Chevy Volt
    He's never heard the brake pressure pumping up before entering the car? I'm thinking the inverter's powering up to supply power to the accumulator.
     
  4. p00kienrayray

    p00kienrayray Active Member

    Joined:
    Mar 14, 2012
    720
    135
    0
    Location:
    Long Beach, CA
    Vehicle:
    2013 Prius
    Model:
    Three
    No, he wasn't referring to the pump sound, rather to the high pitch sound.
     
  5. p00kienrayray

    p00kienrayray Active Member

    Joined:
    Mar 14, 2012
    720
    135
    0
    Location:
    Long Beach, CA
    Vehicle:
    2013 Prius
    Model:
    Three
    Here's an update. So I took the Prius to the local dealer because my sister wanted to check out some Prius C's. I had the service guys check out the noise. They did and said it was a normal sound from the regen brakes. They listened to another Prius and said it had the same noise, although they did note that the high pitch in my car was more loud and noticeable. They said not to worry, and they noted it in my vehicle service file in case any issue does arise later on.
     
  6. retired4999

    retired4999 Prius driver since 2005

    Joined:
    Aug 11, 2011
    2,652
    622
    15
    Location:
    Eau Claire, Wi.
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    (y)
     
  7. HTMLSpinnr

    HTMLSpinnr Moderator
    Staff Member

    Joined:
    Dec 8, 2003
    5,338
    908
    251
    Location:
    Surprise, AZ (Phoenix)
    Vehicle:
    2004 Prius
    Model:
    N/A
    In short, I believe you're hearing the hydraulic controls that actuate the brake pressure itself. I can hear them too if the HVAC and radio are off, and the windows are up. If you really want to be able to record the sound, open the hood and put the mic near the master cylinder/brake booster assembly.

    If the vehicle were moving, yes regen brakes. However, more likely what you're hearing is the hydraulic braking linear solenoids which regulate the amount of hydraulic pressure from the hydraulic brake booster to the wheels. As you actuate the pedal, a stroke simulator is operated (a slave cylinder with a sensor, if you will). This, combined with other factors like speed, stability control, etc., tells the Braking ECU to operate an activate or retract solenoid to add or remove braking pressure to the wheels as cooperative demand requires (with regen having priority at speeds where it is effective). There are also downstream control solenoids to regulate which wheels get that pressure (hold and release) for traction/stability/ABS purposes.

    It stands to reason that when you're stopped, actuating that pedal will immediately operate those solenoids since there's no regeneration opportunity. As you modulate the pedal for more pressure, one solenoid (referred to as SLA in the tech docs) operates. As you modulate less pressure or release, another solenoid operates to relieve pressure (referred to as SLR in the tech docs). Since we don't want all the pressure stored in the brake accumulator (powered by that "rattlesnake" pump you've heard) arriving at once to the wheels (they'd lock), it stands to reason that these are operated intermittently or partially. The docs suggest the solenoids can be partially and continuously opened or closed to regulate pressure. Since most solenoids are "on-off" type devices, operating it partially would require some sort of voltage regulation, which coming from digital systems, is likely going to be high-frequency switched power. At the right frequencies, you'll hear the effects of that switching.

    As a side note - there are other solenoids in place to bypass this system and allow the pressure created by the pedal to go straight to the wheels if this complexity were all to fail.

    Ref: 2010 Toyota New Car Features (NCF) guide - Brake Control Details.
     
    p00kienrayray likes this.
  8. nparker13

    nparker13 Member

    Joined:
    Jun 6, 2009
    121
    13
    0
    Location:
    CT
    Vehicle:
    2010 Prius
    Model:
    V
    I dont mean to scare you but I had a big scare recently regarding a very similar issue. I cant listen to the video since my work blocks just about everything, but here's my story:

    Normally theres a 'recharging' sound after hitting the brakes on my 2010 Gen III Five, but recently, there was an additional sound, something like rubber on metal. I figured it was the housing or something, so I scheduled an appt just to make sure. Sure enough later that week, I went to hit the brake, and it went down to the floor, then once it finally recharged, the brakes kicked in, causing a near miss. I brought it in the next day (there were no ABS lights or anything on the dashboard, and the brakes were fine since the incident, still that weird extra noise though). They said all the lights went on (I thought they were BSing me, because I didnt see them), and a sensor in the brake went bad. They are currently ordering a new sensor $700 later (thankfully I have mechanical insurance through my car insurance company, since I'm out of warranty). Fingers crossed this is the fix.

    TL,DR - take precautions, it could be nothing, but it could be dangerous and expensive.
     
    p00kienrayray likes this.
  9. everydayispoetry

    everydayispoetry New Member

    Joined:
    May 27, 2014
    1
    0
    0
    Vehicle:
    2013 Prius v wagon
    Model:
    Three
    I know exactly what you're talking about, pookie--my new 2013 Prius v (the wagon) has it too. It's very high-pitched, like a ringing in the ears, and while not loud, it's annoying because of the high pitch. It's present often (but not always) while driving, and get louder when braking. However, I only really noticed it when I was driving with the back storage compartment cover off and the black foam storage bins removed, so that the traction battery is acoustically in the same space as the interior of the car. It was driving me crazy until I put those things back, and now the sound is blocked so that I don't really notice it much anymore.

    Is the inverter and it's associated whine that people are talking about back by the traction battery on the v?
     
  10. Mendel Leisk

    Mendel Leisk Titanic Social Director

    Joined:
    Oct 17, 2010
    36,227
    25,036
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Well, the word "pookie" only appears once on this page, so not sure who you're responding to, and over a year back lol. Anyway:

    That whine is music to my ears; it's the sound of charging, the hybrid motor acting as a generator during deceleration.
     
  11. qdllc

    qdllc Senior Member

    Joined:
    Aug 25, 2013
    1,308
    373
    0
    Vehicle:
    2013 Prius
    Model:
    Two
    Are you sure it's not the wife in the seat next to you? :rolleyes:
     
    Mendel Leisk and retired4999 like this.
Loading...