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Stuttering sound when braking - UPDATED WITH AUDIO

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Preeeus, Aug 9, 2016.

  1. Preeeus

    Preeeus Member

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    Our 2010 Prius makes a "stuttering" sound when braking under certain conditions.

    Here are audio examples of this sound: Toyota Prius Braking Noise that Dealership Claims is Normal - Clyp

    The sound only happens when we are gently applying the brakes while turning (either direction) at about 10-15 MPH, especially if that turn has even a slight negative (downward) slope.

    It's like a clicking sound that repeats 5-10 times with maybe 0.1 secondsbetween each click.

    We don't know whether or not it actually has anything to do with the brakes themselves.

    The Toyota Dealership performed an expensive brake inspection, and found nothing wrong. They claim we are hearing "the solenoids for the brakes". And that "the solenoids on the Prius are very loud".

    Those claims would be more believable if we heard this sound every time we braked. But it does not occur all the time, and only occurs when we are braking while driving slowly and are turning at the same time. Also, it did not make this sound until recently.

    Does anyone else's Prius make sounds like this? Any ideas what is causing these sounds?

    P.S. That's not our Prius in the photo!
     
    #1 Preeeus, Aug 9, 2016
    Last edited: Aug 21, 2016
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  2. xliderider

    xliderider Senior Member

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    Do any dash indicators light up when you hear these sounds? Traction control can be activated when the wheels slip on loose gravel, or the wheel speed sensors detect a difference in wheel speed in tight turns (U turns), or while accelerating rapidly in a 90 degree right turn into traffic, etc.

    Our 2011 has recently been making more of a rapid groaning noise sometimes when the brakes are applied. Usually at low speed, and seems to be when the car has been made Ready recently. I was thinking it's the brake accumulator, but I'm not sure. No warning lights accompany these brief noises, and it does it only intermittently.
     
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  3. Preeeus

    Preeeus Member

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    Thanks for your ideas.

    Have not seen any dash indicators light up when we hear these sounds, but we will be extra mindful to notice. We did wonder if it could be anti-lock brakes activating inappropriately during very gentle braking, but the Toyota Dealersip dismissed that notion.

    It happens on smooth asphalt, so it's not a gravel issue. But the wheel speed sensors detecting a difference in wheel speed is an interesting idea. It happens on slow turns that are only 25-90 degrees. Could that still be a possibility?

    Regarding the groaning noise, we have heard that a couple times. Freaked us out the first time we heard it. No idea what caused it, and the Toyota Dealership found nothing in their inspections.
     
  4. The Electric Me

    The Electric Me Go Speed Go!

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    I honestly have no idea what the problems might be.
    But I would say your applied logic in leading to questioning the answer you are being given is sound.

    I would wonder why it doesn't seem to happen every time you brake, and I would also wonder why it seems to happen under the exact conditions you state.

    Did you ask the dealership service department these questions?

    You have a right to not be happy with the answer.

    How difficult might it be to get a second opinion?
     
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  5. Preeeus

    Preeeus Member

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    Thanks for your kind words. Sometimes it's easy to feel like idiots when dealing with this sort of thing.

    We asked the head mechanic at the Toyota Dealership the questions, and he just kept on repeating that "it's the solenoids".

    Getting another opinion is "just" a matter of more money (which we don't have a lot of). The other Toyota Dealership nearby wants $120 for any diagnostic, whether or not they find an issue. With the Toyota extended warranty about to expire, it's tempting, but the thought of throwing away another $120 on inspections is not a pleasant one.
     
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  6. maurices

    maurices Member

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    You don't state how many miles on the car. I wonder if this might be the early onset of one of the front drive shafts going bad. What exacerbates these shafts going bad is when you turn the steering to full left or right stop position. This puts stress on these shafts
     
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  7. bisco

    bisco cookie crumbler

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    is the sound new, or since you purchased the car?
     
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  8. Preeeus

    Preeeus Member

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    A little over 120K miles.

    The sound happens when turning 25-90 degrees, so not typically when the steering is turned full left or right. Given that additional info, does that still sound like a drive shaft issue to you? Thanks!
     
  9. Preeeus

    Preeeus Member

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    We had a discussion about that. As far as we recall, the sound is relatively new. We started noticing it roughly a year ago.
     
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  10. bisco

    bisco cookie crumbler

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    what's your best guess as to where the sound emanates from?
     
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  11. Preeeus

    Preeeus Member

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    Great question. Our best guess is that it comes from both front brakes.

    The Toyota Dealership claims to have performed a full inspection of the brakes, and said they found no issues. We also took it for a test drive with their head mechanic, and he said the sound is the "brake solenoids" and that they are "big and loud on the Prius". He could not explain why they are silent on all braking conditions except when gently braking while turning at lower speeds. He just kept on saying they are real loud on all the Prius vehicles.

    BTW, a friend mentioned the possibility of some sort of traction control system misreading wheel speed sensors and thinking a tire is slipping. No idea if that hypothesis could hold any weight.
     
  12. bisco

    bisco cookie crumbler

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    i guess it's as good as any other. strange that your not getting any dash lights. maybe it's worth checking for codes anyway.
     
  13. Preeeus

    Preeeus Member

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    The dealership said there are no codes or pending codes. We just bought a new code reader to verify it.

    The Prius never made sounds like this a year or two ago, and makes no unusual sounds when braking while going straight. Do solenoids get louder over time?
     
  14. bisco

    bisco cookie crumbler

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    honestly, i've never heard of a brake solenoid. maybe you can ask the parts guy for a number. i wonder if someone could put it on a lift and run the front wheels?
     
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  15. Preeeus

    Preeeus Member

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    This page: Toyota Prius Brake Repair, Pad Replacement mentions "solenoids that manage the regenerative braking". It seems like those would be firing at all speeds and not be influenced by the direction the vehicle is turning.

    If that site is correct, do you know where they would be located? Would they be repeatedly firing while braking?
     
  16. bisco

    bisco cookie crumbler

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    no idea at all. you might have to download the tech service manual. another thought is to take the service manager for a drive in a new one, and ask her why it doesn't make the noise. i think they are just blowing you off because they are clueless.
     
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  17. Preeeus

    Preeeus Member

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    Using advanced recording techniques (holding a digital audio recorder out the window while driving), we have recorded the sounds.

    Here they are: Toyota Prius Braking Noise that Dealership Claims is Normal - Clyp

    So, is the Toyota Dealership correct that these sounds are "just the solenoids firing" and that "everyone's Prius makes those sounds when braking"?

    The attached recording is from driving down a gradual slope (perhaps 3-5% grade) at 10-15 MPH, making a slight left or right turn, and then braking down to about 3 MPH. We then repeated that process multiple times during the recording. You can clearly hear the clicking sound every time we brake.

    Our Toyota extended warranty is getting extremely close to expiring, but with the Toyota dealership claiming that these sounds are completely normal, we do not qualify for any service. We also took the Prius to another dealership, but they were not able to hear these obvious sounds.

    We don't want to pester Toyota if these sounds are normal, but our Prius did not make these sounds a year or two ago.
     
  18. Raytheeagle

    Raytheeagle Senior Member

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    Thanks for the audio. So you only hear the sound during gentle braking and at low speeds? What if you did the same trip that you recorded and applied the brakes more firmly, would the sound repeat? Done a brake inspection to see rotor condition or amount of pads left? You don't have anything that would cause rubbing or contact when turning?
     
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  19. Preeeus

    Preeeus Member

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    You're welcome. Thanks for your interest and help! Here are the answers to your questions:

    We tried it with more aggressive breaking, and it does the same thing. We did not try slamming on the brakes.

    Travelling down any slope, it is trivial to reproduce. On flat streets, it is sporadic. (We did explain this to the Toyota dealership.)

    We just had the dealership perform a full brake inspection, which included the rotors and pads. The measurements were within spec, although a Toyota mechanic at some point got something wrong, because the pad thickness were the same as over a year ago - the Prius conserves pads, but not that much.

    Everything is stock, and the dealership performed a full inspection (including undercarriage), so nothing should be rubbing. Of course, during the last oil change and inspection, the dealership did not even notice that the windshield wiper fluid was empty.
     
    #19 Preeeus, Aug 21, 2016
    Last edited: Aug 21, 2016
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  20. bisco

    bisco cookie crumbler

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    i think they eyeball them and guess.
     
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