Gen 2 brakes cutting in last minute and traction control flashes

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Phunk, Jul 30, 2019.

  1. Phunk

    Phunk Junior Member

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    The Mrs has a 2005 Gen 2 Prius which has been faultless up until recently where 50% of the time when braking the brakes don't kick in till the last minute with a big jolt.

    It should normally transition from regen to braking at around 7mph, instead the traction control light flashes, we hear what sounds like an ABS pump going but no feeling on the pedal and we get a sudden jolt and the brakes jump on.

    The discs and pads were changed around 15k ago and still look pretty fresh, the tyres are all Goodyear with 6mm thread with even pressures. This happens on all road surfaces, dry and wet weather.

    Here's a video showing it working properly the first time, then not working properly the second time (Mrs held the phone whilst I drove!)



    Any ideas what the issue could be?
     
    #1 Phunk, Jul 30, 2019
  2. bisco

    bisco cookie crumbler

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    welcome!
    hard to say, but it might be the brake actuator.

    no dash lights at all?
     
    #2 bisco, Jul 30, 2019
  3. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    How many miles on the 05?

    See if you can locate a hybrid compatible OBD2 code scanner at a parts shop or garage, many will loan or scan for free.

    Once you have the codes read (DTCs), post them here and we can offer further help.

    If no codes are recorded or reported, I would go with what @bisco has offered above.

    If you can you hear the pump running often, it could be slowly failing and will throw a code (DTC) at some point.
     
    #3 SFO, Jul 31, 2019
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  4. Phunk

    Phunk Junior Member

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    Thanks for your help guys.

    The only warning light is the traction control light that flashes (See second half of video)

    I did do a scan using a WiFi OBD scanner with my iPhone that didn't show any error codes (I've used it successfully to clear an engine management light on the car previously)

    The only time I hear it running is 50% of the time when braking lightly to a stop below 7mph.

    The car has 92,000 miles, full Toyota history.
     
    #4 Phunk, Jul 31, 2019
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  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Since your car does not have any warning lights on (besides the momentary tire slip light) I think you should replace the tires.
     
    #5 Patrick Wong, Jul 31, 2019
  6. Phunk

    Phunk Junior Member

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    Why do you think replacing the tyres would resolve this issue? They’re Goodyear’s with 6mm
     
    #6 Phunk, Jul 31, 2019
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Because the slip light comes on, hence a tire is slipping and not doing its job.
     
    #7 Patrick Wong, Jul 31, 2019
    Last edited: Jul 31, 2019
  8. Skibob

    Skibob Senior Member

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    Someone else had a similar problem recently. They recalibrated the actuator using techstream and the problem went away.

    Problem with creep? | PriusChat
     
    #8 Skibob, Jul 31, 2019
    Last edited: Jul 31, 2019
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  9. ChapmanF

    ChapmanF Senior Member

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    I don't know if the Gen 2 traction control is like Gen 3 in this way, but with Gen 3 you can use Techstream and pull up the last several (four? I think) times the traction light flashed, and what was happening at the time: acceleration/deceleration, turning, g forces, car speed, wheel speeds, the works. That might reveal a lot about what the car thinks is going on.
     
    #9 ChapmanF, Jul 31, 2019
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  10. Phunk

    Phunk Junior Member

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    Just to update this thread and bring it to a close!

    I bought techstream and spent several hours battling with it to try and get it to work (and failed)

    So I took it to a local garage who plugged into the ODB and diagnosed a faulty front left ABS sensor. I then removed the sensor and cleaned it which didn’t help.

    I managed to get a new sensor from eBay for 25 and fitted it in around 40 minutes, then used the paper clip trick to reset the ABS light and the problem has now gone!
     
    #10 Phunk, Sep 29, 2019
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  11. bisco

    bisco cookie crumbler

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    congrats!(y)
     
    #11 bisco, Oct 2, 2019
  12. Emmawellz

    Emmawellz New Member

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    Hello, I’m experiencing this same issue on my Toyota Prius 2006, and I’ve tried everything I can, I even got a new abs module but that did not fix it. I’m currently confused and frustrated.
     
    #12 Emmawellz, Apr 1, 2022
  13. ChapmanF

    ChapmanF Senior Member

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    I don't know if the Gen 2 traction control is like Gen 3 in this way, but with Gen 3 you can use Techstream and pull up the last several (four? I think) times the traction light flashed, and what was happening at the time: acceleration/deceleration, turning, g forces, car speed, wheel speeds, the works. That might reveal a lot about what the car thinks is going on.
     
    #13 ChapmanF, Apr 1, 2022
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  14. mr_guy_mann

    mr_guy_mann Senior Member

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    Does the ABS system have any codes?

    My first thought is (as above) that a wheel speed sensor is glitchy and the signal drops out at low speed. The ecu interprets this as lock up and uses the hydraulic brake ABS function to try and control that. On the Gen2 the transition from normal regen braking to (sudden) ABS function is not very smooth

    I would look at data for all 4 wheel speed sensors on a scantool as the car decels (no braking) from 15 mph to 0. See if any one reads lower or erratic compared to the other three.

    Posted via the PriusChat mobile app.
     
    #14 mr_guy_mann, Apr 2, 2022
    Last edited: Apr 2, 2022
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  15. ChapmanF

    ChapmanF Senior Member

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    I think Techstream's "ABS history" display (that's what I think I remember it's called) is what I was mentioning in #9 above, and I think it saves all the vehicle dynamics info from the last 4 times any activation of either ABS or VSC happened. Like freeze frames for a trouble code, but collected when there's no trouble code reported and ABS or VSC is just doing its thing.
     
    #15 ChapmanF, Apr 2, 2022
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