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Strange brake lock and release issue

Discussion in 'Gen 2 Prius Technical Discussion' started by Gen2prius2007, Apr 30, 2023.

  1. Gen2prius2007

    Gen2prius2007 Junior Member

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    Hi all.

    I have a Gen 2. Recently, I have been experiencing a strange issue. Whenever I apply light pressure on the brake pedal while turning, I hear a sound from the front wheels that resemble brake locking and releasing continuously until I release the pedal. The constant clunking noise is the same when you apply the brakes hard on a straight road and hear the system continuously locking and releasing the brakes to avoid skidding the tires. But as I said above, the same thing happens ONLY when I turn the wheel a little (left or right) and apply light braking while doing so.

    My ABS is brand new, and I even changed the whole caliper set on both sides, but the issue remains the same. I thought of pads, too, but I have tried 3 or 4 pairs. Has anyone here ever experienced the same issue, and what can I do to fix this problem? Thanks.
     
    #1 Gen2prius2007, Apr 30, 2023
  2. SFO

    SFO Senior Member

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    Are there warning lights being displayed on the dash, or any obd2 codes worth posting?
     
    #2 SFO, May 2, 2023
  3. Gen2prius2007

    Gen2prius2007 Junior Member

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    No warning lights or codes of any kind.
     
    #3 Gen2prius2007, May 2, 2023
  4. SFO

    SFO Senior Member

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    You might try jacking up the front to see if the noise continues, or is able to be found. This may require a second person, and jack stands.
     
    #4 SFO, May 5, 2023
  5. mr_guy_mann

    mr_guy_mann Senior Member

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    Try using the brakes hard on dirt road or gravel- a place where you know that the ABS will have to work. When you do that, see if the amber "slip" indicator on the dash lights up. (looks like a car with wavy lines under it).

    The idea is to see if that indicator works or not. If the ABS or traction control is "falsely" activating, then the indicator should flash on when it does.

    Assuming that is what's happening, then I would be looking at one of front wheel speed sensors. Maybe one has an intermittent open circuit when the wheels are turned away from center.

    If you have a capable scantool, then another test would be to unplug any wheel speed sensor. There will be warning lights on, but this will prevent ABS function. Test drive the car and see if your symptom is still there.

    If it goes away, then look at those speed sensors.

    Posted via the PriusChat mobile app.
     
    #5 mr_guy_mann, May 7, 2023
    Last edited: May 7, 2023
  6. Gen2prius2007

    Gen2prius2007 Junior Member

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    Thanks, guys. I got the issue diagnosed and fixed. Both axles were bad but only to the extent that they generated that noise on braking while steering is slightly turned left or right. Replaced them and the issue is gone.
     
    #6 Gen2prius2007, Jun 14, 2023
    mr_guy_mann, SFO and bisco like this.
  7. bisco

    bisco cookie crumbler

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    Congrats!
     
    #7 bisco, Jun 14, 2023
  8. mr_guy_mann

    mr_guy_mann Senior Member

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    Thanks for the update!

    Interesting, usually bad CV joints on an axle will make noise (a metallic click-pop) on turns when applying throttle -torque on the axles in forward or reverse.

    I never associated "noise on braking" with bad CV joints. I hadn't considered that regenerative braking also puts "reverse torque" on the axles.

    Posted via the PriusChat mobile app.
     
    #8 mr_guy_mann, Jun 14, 2023
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