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Prius Extremely Hard Braking at Low Speed, Problem?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by comatoes, Nov 23, 2011.

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  1. comatoes

    comatoes #GreenLife

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    My 2007 Prius brakes extremely hard at low speed (while I am applying the same amount of pressure). While decelerating, I let the regen braking do most of the work until I get to about 10mph, then I press the brake so I will have equal pressure until I stop. When I get to about 5mph I feel almost a lunge where the brakes aren't working as hard and then the brakes take hold extremely hard. My prius has been doing this for awhile not depending on the weather, but I finally noticed it worse than normal yesterday when it was raining and my car braked hard and actually skid and the traction control light came on.

    Sorry for the long post, has anyone else experienced something similar? Should I get this checked out?
     
    #1 comatoes, Nov 23, 2011
  2. jdcollins5

    jdcollins5 Senior Member

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    It sounds like you may have rust buildup on your brakes. The next time you are braking for a stop, without traffic in front, switch to neutral which will disable regen braking and enable friction braking. Brake with a slow, even pressure to allow the pads to wipe the rotor. Do this a couple of times and see if your grabby brake issue goes away.
     
    #2 jdcollins5, Nov 23, 2011
    Keen and comatoes like this.
  3. bisco

    bisco cookie crumbler

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    sounds like a plausible diagnosis to me, although, if you've been driving it for 5 months and it's only been doing it for awhile, i would think it might be an electronic or hydraulic problem.
     
    #3 bisco, Nov 23, 2011
  4. richard schumacher

    richard schumacher shortbus driver

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    Or ease off on the pedal when they start to grab.
     
    #4 richard schumacher, Nov 23, 2011
  5. Rokeby

    Rokeby Member

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    I'm going to guess that you park the car outside.

    I have noticed this same condition from time to time...

    It is in fact associated with rainfall; rain water getting to the front discs
    while the car is parked. For me, it can be particularly noticeable after
    my car sits unused in the rain for a day or two.

    It has been noted elsewhere that the Prius' brake discs are especially
    prone to light surface rusting/oxidation when wetted and left standing.

    FWIW, the get-up-to-speed, check-for-traffic, shift-to-neutral, apply-
    brakes and repeat drill has always worked to clear the issue for me.
     
    #5 Rokeby, Nov 23, 2011
  6. The Critic

    The Critic Resident Critic

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    I had similar issues, then recently had a linear solenoid calibration done and the issue has not come back...at least for now.
     
    #6 The Critic, Nov 25, 2011
  7. comatoes

    comatoes #GreenLife

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    Thanks for all the responses, I want to add something else I noticed/forgot.

    Yesterday I was driving and the ABS light, VSC, and ((!)) light came on. I pulled of the road and shut the car off and waited about 10 minutes. I turned the car back on and saw they were still there so I drop about 5 miles home and left the car sit (outside always) overnight. This morning the lights were not on.

    I forgot to mention about 6 months ago, those lights I mentioned above came on but were off the next morning and I didn't see them again until now.

    I have never seen any red indicator lights.
     
    #7 comatoes, Dec 6, 2011
  8. seilerts

    seilerts Battery Curmudgeon

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    if abs/vsc lights are on, have the codes read at the dealer, or jumper the data link connector to get the blink codes and post them here. This isn't something to mess around with, as a failure within the hydraulic system will make it extremely difficult or impossible to stop the car once it is going too slow for regen. See post #7 in the thread below for instructions to jumper the DLC.

    http://priuschat.com/forums/gen-ii-...o-you-reset-abs-light-yellow.html#post1239054
     
    #8 seilerts, Dec 6, 2011
  9. comatoes

    comatoes #GreenLife

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    I have an obd2 scanner and torque and I read the codes and there went any. .
     
    #9 comatoes, Dec 6, 2011
  10. V8Cobrakid

    V8Cobrakid Green Handyman

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    did these lights come on during a long turn? (random question... i know)
     
    #10 V8Cobrakid, Dec 6, 2011
  11. comatoes

    comatoes #GreenLife

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    No not really. I had just commuted from work 8 miles stop and go, turned off car for 20 minutes, drove slow for 6 miles. Turned off car for an hour. Drove 2 minutes and lights came on.
     
    #11 comatoes, Dec 6, 2011
  12. V8Cobrakid

    V8Cobrakid Green Handyman

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    how old is your 12v battery?
     
    #12 V8Cobrakid, Dec 6, 2011
  13. comatoes

    comatoes #GreenLife

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    No clue, I bought the car used 6 months ago. I saw that in a forum on PC and thought about that.
     
    #13 comatoes, Dec 6, 2011
  14. comatoes

    comatoes #GreenLife

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    I did this free roll braking a few times on the way back from work, it seemed to help! I'll test it tomorrow and post. Thanks!
     
    #14 comatoes, Dec 6, 2011
  15. seilerts

    seilerts Battery Curmudgeon

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    Generic scanners will not read Toyota proprietary brake codes.
     
    #15 seilerts, Dec 6, 2011
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  16. comatoes

    comatoes #GreenLife

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    Hmm.. so there wouldn't be a non Toyota specific OBD2 readable error code if the brakes were faulty?
     
    #16 comatoes, Dec 7, 2011
  17. seilerts

    seilerts Battery Curmudgeon

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    All that you need to do is jumper pins 4 and 13 of the DLC to get the flash codes, which then can translate to 4 digit C codes. Each warning lamp with flash out a 2 digit code when you turn on the car with the pins jumpered.
     
    #17 seilerts, Dec 7, 2011
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  18. comatoes

    comatoes #GreenLife

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    I'm not really electrically inclined so I might not do this. I am however going to the dealer in 2 weeks to get recalls done: floormat and water pump.. Does anyone have an idea of how much Toyota charges to look at the VSC/ABS error codes? Also, the fact that the error lights don't stay on (ie. I haven't seen them the past 2 days) mean that there isn't really a problem but a false reading twice in 6 months?
     
    #18 comatoes, Dec 7, 2011
  19. comatoes

    comatoes #GreenLife

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    I just talked to the dealer, they said a diagnostic will cost $95. Is there a safe(r)/recommended way to do this?
     
    #19 comatoes, Dec 7, 2011
  20. jdcollins5

    jdcollins5 Senior Member

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    Not unless you want to buy a scanner that will read Prius specific codes, something like the ScanGaugeII from Prius Chat Shop that a lot of people here have done. The ScanGauge is about $150.
     
    #20 jdcollins5, Dec 7, 2011
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