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Cruise Control not available when drive selector is in B

Discussion in 'Gen 4 Prius Main Forum' started by Gary Boates, Mar 27, 2017.

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  1. Gary Boates

    Gary Boates Junior Member

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    Cruise Control not available when drive selector is in B - info not in a User Manual
     
    #1 Gary Boates, Mar 27, 2017
  2. David Beale

    David Beale Senior Member

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    Same as GII and GIII. Probably because it would be a little noisy in "B" and might "freek out" the driver.
     
    #2 David Beale, Mar 27, 2017
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  3. Gary Boates

    Gary Boates Junior Member

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    The Gen4 is my first Prius and finally I had reasons to buy one... just how quiet and tight and silky the ride is was my main motivator. During the first two weeks I had many trips to our service manager trying to nail down this 'no cruise in B issue' - surprised to hear that other generations have this same feature, or lock out more accurate, and yet nobody could figure it out. In fact we never associated it with B due to a lot of hills and I was driving in B 50% of the time. I just thought the cruise was flakey. Shifting out of B and back into D on the fly was a learning experience as well. The auto brake self save feature is awesome too. I like a lot about this car - dash dimming - touch screen shutoff for night driving - just that damn READY light. Duh.
     
    #3 Gary Boates, Mar 27, 2017
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  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    #4 JimboPalmer, Mar 27, 2017
    Last edited: Mar 27, 2017
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  5. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Leave it in D. I'm not trying to be dismissive: 99% of the time D is the best option. Reserve B for coming down LONG mountain roads.
     
    #5 Mendel Leisk, Mar 27, 2017
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  6. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Asked and answered.
     
    #6 ETC(SS), Mar 27, 2017
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  7. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    #7 JimboPalmer, Mar 27, 2017
  8. Gary Boates

    Gary Boates Junior Member

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    Thanks. We have lots of long downhills. I also wonder the effect over time of having used the compression dump on long downhills. Hate for it to start to leak on its own. Any engine experts ?
     
    #8 Gary Boates, Mar 27, 2017
  9. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    No part of nova Scotia is over 1755 feet above sea level, and that is a National Park. (you could have a 1500 foot (450 m) drop off North Mountain, in the park) Parks Canada - Cape Breton Highlands National Park - Cape Breton Highlands National Park

    B mode is mostly useful on vertical drops of over 600 feet, (185 m) as the NiMH battery fills up about there, I am not sure of the capacity the LiIon batteries. The capacity of the Plug-Ins is much higher, so B mode works differently.

    I confess I have only been near Halifax, via cruise ship tours, so I am not as familiar as I am to Vancouver and Toronto.
     
    #9 JimboPalmer, Mar 27, 2017
    Last edited: Mar 27, 2017
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  10. fuzzy1

    fuzzy1 Senior Member

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    Are they long enough to fill the HV battery? I.e. more than 500-ish vertical feet if steep (>=5% slope), more vertical if shallower?

    B is generally unwarranted and wasteful on hills shorter than that.
     
    #10 fuzzy1, Mar 27, 2017
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  11. kevinwhite

    kevinwhite Active Member

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    What do you mean by "Hate for it to start to leak on its own."?

    Engine braking is not damaging for the engine - it is not like a "Jake Brake" on trucks. It just uses the engine pretty much as normal but no fuel is supplied to it and the throttle is held closed. They may alter the valve timing a bit but that happens during normal operation as well.

    kevin
     
    #11 kevinwhite, Mar 27, 2017
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  12. bisco

    bisco cookie crumbler

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    welcome to priuschat! congrats on your new gen 4, all the best!
     
    #12 bisco, Mar 27, 2017
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  13. alanclarkeau

    alanclarkeau Senior Member

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    I've only used "B" once - how do you get it back from "B" to "D"?

    I ended up putting it in "N" and then could go back to "D".
     
    #13 alanclarkeau, Mar 27, 2017
  14. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    You get to D to the left and down, same as always.
     
    #14 JimboPalmer, Mar 27, 2017
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  15. kevinwhite

    kevinwhite Active Member

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    "99% of the time D is the best option"

    Not only that but the car will automatically use engine braking in D anyway.

    I've seen over 4000RPM in D with DRCC engaged. Without cruise control it needs you to be braking for the engine braking to come into effect.

    kevin
     
    #15 kevinwhite, Mar 27, 2017
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  16. ChapmanF

    ChapmanF Senior Member

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    My experience also. I've had two Prii, a Gen 1 and a Gen 3, and the cruise control changed in between.

    In Gen 1, they were rushing to get this new car out the door, and more or less reused a cruise control circuit for a conventional car. It's built into the HV ECU, but it just thinks it's pulling on an accelerator cable. It'll make the car pull harder on uphills, but has little effect to restrain the speed on downhills. But you could shift into B and then it sort of would, just because of the extra drag simulated by B when the pedal is released.

    So I was disappointed to get my Gen 3 and find that now you can't engage cruise in B (and also, if cruise is engaged and you shift to B, it disengages). But it turned out not to be a loss of function, because in the meantime they designed a more hybrid-specific cruise control, that will naturally use the hybrid system to restrain speed on downhills, in D, without you having to do anything special (and it will transition on its own to engine braking whenever appropriate).

    -Chap
     
    #16 ChapmanF, Mar 27, 2017
  17. alanclarkeau

    alanclarkeau Senior Member

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    Thanks - I'll try that again. It didn't seem to work last time that way, but maybe I rushed it?
     
    #17 alanclarkeau, Mar 27, 2017
  18. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    I just pull down and diagonally towards myself, without looking. Like maybe 7 oclock direction.
     
    #18 Mendel Leisk, Mar 27, 2017
  19. Gary Boates

    Gary Boates Junior Member

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    Thanks Kevin! Yes I see now how it works mechanically. So I guess it's just my decision as to wanting to use the mechanical disc brakes on a down hill or if I decide to select B and stress the engine's cylinders and components by using it as an "air brake".

    Lastly I found this:

    "If you are in B, don't worry about the engine making a lot of noise and worry about "breaking something". The engine is not burning fuel and compressed air generates far less heat than exploding fuel. The cooling system is active, so there is plenty of cooling going on to keep temperatures at their nominal levels, and no charging is done and currents are really low, so the whole power conversion and electric motor driving is essentially off.
    Braking down a steep slope in B, when regular braking is not enough anymore or not desired, may sound horrible, but it is the best thing to do."
     
    #19 Gary Boates, Mar 28, 2017
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  20. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    The first time you use it, the fact that the more you press on the brake, the louder the engine gets, is counter intuitive.
     
    #20 JimboPalmer, Mar 28, 2017
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