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Prius V Dynamic Cruise Control Safety

Discussion in 'Gen 3 Prius Main Forum' started by maomao, Jul 18, 2010.

  1. maomao

    maomao New Member

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    One of the best features of my 2010 V is the cruise control. I think it worth every peny for the ATV upgrade. It significantly cuts the fatigue in long distance driving. I used to take two rests driving from DC to NYC. But I did not have to rest in my last trip.

    But I have always been wondering what happens with my car's brake lights when the cruise control automaticaly applies brakes. When the car in front of me slows down, my car also slows down without my foot on the brake pedal. I am afraid if my brake lights does not light, the driver behind me may not get the warning early enough to slow down, and I would be more likely to get hit from behind.

    Does any of the V owners here know better? Please clarify to ease my worries. Thanks!
     
    #1 maomao, Jul 18, 2010
  2. macman408

    macman408 Electron Guidance Counselor

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    To the best of my knowledge, it lights them at the same braking force as it would if you were pushing the brakes yourself. In other words, if it's just simulating engine drag, they won't light. More than that and they will. That said, some people have complained that the Prius doesn't light the brake lights early enough when braking.

    If you want to see for yourself, find an empty road late at night with signs or trees nearby so that you can see in your rear view mirror when the brake lights turn on. Turn on cruise control, then hold the lever down to reduce the set speed, and it should brake once the difference is large enough.
     
    #2 macman408, Jul 18, 2010
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  3. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    FYI, you dont need the brake lights anyways. In my 5sp, I engine brake all the time, which doesnt light the brake lights. It's not as big of a problem as people make it.
     
    #3 2k1Toaster, Jul 18, 2010
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  4. maomao

    maomao New Member

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    Thank you. It's a good idea to test it this way.

     
    #4 maomao, Jul 18, 2010
  5. Tideland Prius

    Tideland Prius Moderator of the North
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    The other way is to switch to the HSI when you're in DRCC. Just look at how much the bar is into the CHG area. That way, you can tell if the car is just coasting or pressing the brake pedal (and hence lighting up the brake lights).
     
    #5 Tideland Prius, Jul 19, 2010
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  6. maomao

    maomao New Member

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    That's interesting. But how should I read the bar? Does this mean I can tell the brake light is on when the bar reaches certain level? What's the threshold then? Thanks.
     
    #6 maomao, Jul 19, 2010
  7. creativeguy

    creativeguy Member

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    You actually do need the brake lights! The DRCC can slow the car very quickly in a situation where someone cuts in front of you. The deceleration is much quicker than engine or gear braking.
     
    #7 creativeguy, Jul 19, 2010
  8. Tideland Prius

    Tideland Prius Moderator of the North
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    The same way you read the bar when you're driving. Note how much the bar extends to the left when you're coasting. The same applies to DRCC. If you see the bar longer than what you've determined as coasting, then the DRCC is using the brakes.
     
    #8 Tideland Prius, Jul 20, 2010
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