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WOW Pre-Collision System Activated

Discussion in 'Gen 4 Prius Main Forum' started by bestmapman, Jul 24, 2017.

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  1. bestmapman

    bestmapman 04, 07 ,08, 09, 10, 16, 21 Prime

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    After 16,000 miles on our 2016 Prius 4 with ATP, for the first time, the Pre-Collision System activated and most likely prevented a collision.

    I was entering a freeway. Four or Five cars were in front of me on the onramp as I was accelerating to merge into the right hand lane. Traffic was medium to heavy and I needed to find a place to merge into. The speed of the traffic on the freeway was 60 to 65 MPH. As I was looking back, the fouth or fifth car in front of me decided that there was no room (actually I had no idea what he he could have been thinking) and came to a complete stop on the on ramp. Wth$%^&? Needless to say all the other cars including me had to stop. The problem was, I was looking back for a spot to merge into when all the cars in front of me had started to a stop and I was still accelerating.

    The next sequence of events all happened at about the same time and I am not sure what happened first or in exact order, as it happened SOOO!!! fast. Here is what I think happened.

    I heard a beeping warning
    I saw a big red rectangle on the dash with white letters that said BRAKE
    I saw the cars stopping
    My wife screamed "Watch out" (I think she added "you idiot" but denies it)
    The car slammed on the brakes
    I slammed on the brakes (I think the car beat me to the brake pedal)
    The car vigorously braked, so strong the anti-lock brakes activated on dry pavement.
    The car stopped. I estimate four or five feet from the car in front of me.
    I let off the brakes, but the brakes did not disengage.
    Two or three seconds later the brakes disengaged
    I continued on the freeway a little shaken.

    Noted other effect of Pre-Collision system activation:

    This episode generated two or three hours of non stop lecturing about traffic safety and other driving techniques.
     
    #1 bestmapman, Jul 24, 2017
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  2. MichelleStone

    MichelleStone Senior Member

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    I had much the same thing happen to me a while back. It's an amazing system, isn't it?
     
    #2 MichelleStone, Jul 24, 2017
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  3. Tyfly

    Tyfly Member

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    The system really is incredible. My 17 Prius prevented me from rear-ending a truck after traffic slowed from 70 to 30. I was braking as hard as I could but the car decided I wasn't applying enough force and braked even harder. Glad the system worked for you as well. It just paid for itself.
     
    #3 Tyfly, Jul 24, 2017
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  4. wenglish

    wenglish Junior Member

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    Impressive. You were lucky the driver behind you didn't hit you while doing her same as you (looking over their shoulder for a gap, and accelerating). Or were they in a recent model Toyota too? :)

    The sooner we get all cars communicating with each other the better. Until someone hacks the system of course.
     
    #4 wenglish, Jul 24, 2017
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  5. CooCooCaChoo

    CooCooCaChoo Active Member

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    If you watch the Energy Monitor when braking, it shows increased recharge. This is because when you hit the brakes, it actually increases recharge rate before it hits the mechanical brakes thus saving the wear and tear on the brake pads. This is the reason why the brakes and pads almost never need to be replaced.

    I've seen the BRAKE message myself come on twice since owning my 2017 due to drivers not knowing where they were going.
     
    #5 CooCooCaChoo, Jul 24, 2017
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  6. FuelMiser

    FuelMiser Senior Member

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    I think that's the last thing you'd want to be looking at in an emergency braking situation. It would all be over so fast anyway.
     
    #6 FuelMiser, Jul 24, 2017
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  7. Since2002

    Since2002 Senior Lurker

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    I wonder if there is a maximum that the system will brake when the driver applies force to the pedal, but maybe PCS will exceed that if it senses that a crash is imminent. Perhaps combining maximum regen and maximum friction braking at the same time, of course modulated by ABS.
     
    #7 Since2002, Jul 24, 2017
  8. CooCooCaChoo

    CooCooCaChoo Active Member

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    Obviously don't do it when you are in traffic or in an emergency situation. Gotta take the time to notice the behavior of the vehicle when driving it under various conditions to know what is normal and not normal, and what the car's on-board computers do.
     
    #8 CooCooCaChoo, Jul 24, 2017
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  9. Tideland Prius

    Tideland Prius Moderator of the North
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    The PCS seatbelts would've activated too (and you probably didn't notice). I found the Gen 4 to be more sensitive than the Gen 3 (probably because it has a camera to help the radar while the Gen 3 doesn't).

    Glad it worked out and saved your butt!
     
    #9 Tideland Prius, Jul 24, 2017
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  10. RCO

    RCO Senior Member

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    Pity it has no way of attenuating the persistent nagging lecture from the passenger seat area as well.
    :eek::(

    Edit: regarding post #1
     
    #10 RCO, Jul 25, 2017
    Last edited: Jul 25, 2017
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  11. Prodigyplace

    Prodigyplace Senior Member

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    You didn't get the optional muzzle? :eek: :LOL:
     
    #11 Prodigyplace, Jul 25, 2017
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  12. RCO

    RCO Senior Member

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    LOL. I was really referring to the last sentence from OP in #1:)
     
    #12 RCO, Jul 25, 2017
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  13. tucatz

    tucatz Active Member

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    Awesome! Glad the PCS saved you and yours. Mine has activated too, possibly preventing an accident. The computer reacts faster and more precisely than a human being.

    Remember to update your profile and change your avatar.
     
    #13 tucatz, Jul 25, 2017
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  14. David Beale

    David Beale Senior Member

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    Those comments of "regen braking" are rather superfluous. I'm absolutely sure the "friction brakes" -vastly- out-power the regen braking, and both are limited by tire traction anyway, as already posted. In other words, the Prius doesn't need regen braking in an emergency situation, whether or not it uses it. ;)
     
    #14 David Beale, Jul 27, 2017
  15. wrprice

    wrprice Active Member

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    Regen is antithetical to emergency braking anyway. The skid control system and ABS want to micromanage each wheel in that situation. Since regen is applied centrally from within the HSD, rather than at each wheel like brake pads, it would work against that effort.
     
    #15 wrprice, Jul 27, 2017
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  16. JimN

    JimN Let the games begin!

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    In my 2010 one would have to be dead to not notice PCS retracting the seat belts. They release after a few seconds.

    Perhaps the Cone of Silence is only offered in DC's region and the ejector seat in England.
     

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    #16 JimN, Jul 27, 2017
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  17. wrprice

    wrprice Active Member

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    "Missed it by *that* much." -- Agent PCS
     
    #17 wrprice, Jul 27, 2017
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  18. tucatz

    tucatz Active Member

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    What?
     
    #18 tucatz, Jul 27, 2017
  19. alanclarkeau

    alanclarkeau Senior Member

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    Not on my PCS - it beeped at me this morning, I was in a line of traffic and about to slip through a gap - but the seat belt didn't retract. I've had it apply the brakes, but don't recall it retracting my belt.

    Yes, a Cone of (relative) Silence, quietest car I've had.
     
    #19 alanclarkeau, Jul 28, 2017
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  20. Tideland Prius

    Tideland Prius Moderator of the North
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    I've never noticed it retracting the seatbelts..... I've only noticed it when it relaxes my seatbelt back to normal (and I hear the electric motor whine in my left ear). You're too busy dealing with the situation to notice the seatbelt retracting.

    On the Gen 3, you have to be travelling above 60km/h and release the accelerator rapidly followed by depressing the brake pedal. The Gen 4 may function differently. It has occurred both with a light tap on the brake pedal and a moderate effort on the brake pedal so I think it's looking for the combination of both a rapidly release of accelerator plus a depression of the brake pedal immediately after.
     
    #20 Tideland Prius, Jul 28, 2017
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