I think I found a brake system bug (grabby). Here's the workaround.

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by usbseawolf2000, Apr 15, 2013.

  1. usbseawolf2000

    usbseawolf2000 HSD PhD

    Joined:
    Sep 22, 2004
    14,487
    3,000
    0
    Location:
    Fort Lee, NJ
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    I think I found a bug with the brake system in my PiP, regarding how the friction pads are blended.

    Here is my situation. I pull into my garage with the head in (and turn off the car). I made this change due to the location of the charging port. So when I go out, I back out of the garage.

    After reversing (R gear) out of my garage, I used to put my PiP into D gear (without braking to a complete stop) and then drive off.

    Here is the bug. If I hit the brake lightly (only regen brake expected) under 40 mph, sometimes the friction pads kicks in for a split second. This causes the car to "jolt" as if I slam on the brake and release it after a split second. The level of "jolt" caused by this depends on the speed at when it occurs.

    If I back out of my garage and make a full stop first (using the brake) and then drive forward, the "jolt" does not happens.

    This may explain and provide a solution to those reporting "grabby brakes" in Gen3 regular Prius. I doubt this issue is unique to PiP.

    If you have a PiP or a regular Gen3 Prius, please try to reproduce it -- to prove my theory. If this information is old, please lock the thread. I doubt it since Toyota has not fixed it since the 2010 model. If nobody can reproduce it, perhaps my PiP has a defective brake system.
     
    #1 usbseawolf2000, Apr 15, 2013
  2. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,910
    1,908
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    All Prii can exhibit "grabby" friction brakes. The problem source is that we make very little use of the friction brakes and the rotors get rusty. The solution is to periodically force the use of the friction brakes to clean the rotors.
    1. Get up to 25-30 mph on a road with no other traffic.
    2. Put your Prius in neutral (disables regenerative braking)
    3. lightly apply the brakes and you will hear a scraping sound.
    4. repeat and the scraping will diminish
    5. Your brakes should show better behavior at the transition between regeneration and friction (usually at about 7 mph)
    JeffD
     
    #2 jdenenberg, Apr 15, 2013
  3. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    111,559
    50,803
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    i have not seen hte grabiness, and my rotors were really rusted after sitting in the garage for a month. i also back out of my garage, back have to use the friction brakes because my driveway goes downhill to the street. so i'm applying them from when i hit the driveway to about half way into the street. then i let off, throw it in drive and use throttle to reverse direction. i did the same thing with gen II's, but ice was running of course.
     
    #3 bisco, Apr 15, 2013
  4. usbseawolf2000

    usbseawolf2000 HSD PhD

    Joined:
    Sep 22, 2004
    14,487
    3,000
    0
    Location:
    Fort Lee, NJ
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Yes, I am aware of that and it happens especially after a raining day. It pretty much goes away after the first "grabby" experience. Rusted rotor grabbing only happens around 7 mph or brake hard enough to trigger friction pads.

    The bug that I reported grabs harder and it is persistent -- the "grabbiness" does not fade with the same drive. It happened a few time at around 40 mph and the "jolt" was pretty hard as if I hit a wall for a fraction of a second, during a light brake (expecting only the regen).
     
    #4 usbseawolf2000, Apr 15, 2013
(You must log in or sign up to post here.)