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Driving on packed snow long distance

Discussion in 'Gen 2 Prius Main Forum' started by bobjeri, Feb 14, 2009.

  1. bobjeri

    bobjeri New Member

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    ABS&B&VSC
    In post #15 Pat wrote this--
    " Should the front wheel start to slide while in B mode with no foot on the brake it will continue to slide."

    IMHO -- This is not inconsistent with recent posts which state that ABS will not engage until the brake pedal is pressed.

    I've driven long gentle icy strait downhills to long steep constantly tight curved ones. It seems the Prius has capabilities which are superior to many cars in these conditions so the driver just uses reasonable judgement and knowledge and skill.... as always.

    There is a congruent concern to what fishing writer John Geirach said about 4WD--

    "All 4 wheel drive does is allow you to get stuck is worse places."
     
  2. jayman

    jayman Senior Member

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    I've always driven a 4wd in 2H, so when the vehicle bogs down, I shift into 4H, back the hell out of there, and try someplace else
     
  3. qbee42

    qbee42 My other car is a boat

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    Taking your foot off of the gas causes a small amount of regenerative braking. This is done to simulate engine drag in a normal car. Sliding drive wheels will disable regenerative braking, switching to friction braking. With friction braking, no braking action occurs unless then brake pedal is depressed. Without any braking action you don't get ABS, so in a long round-about fashion you can see why you don't get ABS without pressing the brake pedal. It would be equally correct to say that you do get ABS, but with zero braking. At zero braking ABS is equivalent to non-ABS.

    Tom
     
  4. bruceha_2000

    bruceha_2000 Senior Member

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    I believe this is incorrect. I don't think there is ever any engine braking involved when in D mode.

    My basic concept of B mode use is: If you have to ride the brakes most or all of the time to hold speed down the hill, shift to B. You might still have to use the brake pedal on steep hills or add a little throttle now and then to hold speed.

    Not that the OP will be using it in the conditions he is expecting, cruise will not engage while in B and shifting to B will disengage cruise.

    With regard to VSC, yes it works quite nicely :) I've never had it go on when I wasn't braking, but I ASSUME it will do so if you start to slide out sideways even when you aren't braking. The two times it went on (briefly) when I WASN'T testing it, I was going just a little too fast on a turn when I hit a more slick patch of snow/ice. VSC kicked right in and 'fixed' it about the same time I realized I was starting to skid. So, yeah, the computer is faster than the driver.

    If you see the TC light flashing on the dash AND hear the chimes, VSC is trying to keep your back end for passing your front end. Time to SLOW DOWN.
     
  5. qbee42

    qbee42 My other car is a boat

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    There can be, but only in what I think of as "auto B mode". If the SOC reaches a high threshold while regeneratively braking in D mode, the system will automatically invoke engine braking. It appears to be a little less aggressive than true B mode, but it is essentially the same.

    Tom
     
  6. bobjeri

    bobjeri New Member

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    In post 23 Tom wrote--
    "Without any braking action you don't get ABS, so in a long round-about fashion you can see why you don't get ABS without pressing the brake pedal. It would be equally correct to say that you do get ABS, but with zero braking. At zero braking ABS is equivalent to non-ABS."

    Yep. Dat's purty much howl i unnerstans it now.

    It is really extra ordinary how much patience and time folks spent helping me with this ... thanks. About 7-8 miles away is a small hiking trail parking lot which is reported to be ice covered ... think I'll wander over there.