Did you know ?? Cruise Control is disabled if in 'B' mode ?

Discussion in 'Gen 3 Prius Main Forum' started by revhigh, Jun 15, 2011.

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  1. revhigh

    revhigh MPG Enthusiast

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    Funny thing ... about 2 months ago, I was driving and my cruise control wouldn't engage on the highway ... I happened to be right near the dealership so I immediately returned there .... didn't turn off the car, but the tech put it in P while I was waiting. I was so ticked off because I thought that may have 'reset' things, and of course when the tech took the car for a drive (in D) the cruise worked fine. We of course never confirmed that the cruise control didn't work.

    Today, the same thing happened at the same place, so I returned to the dealership, calling them on the phone, and informing them that I would not turn the car off, or allow the car to be put in park. The service manager met me out front and we went for a quick ride so I could 'prove' that the cruise was inoperative. He confirmed that it was not working, and had no idea why. For some reason, I glanced at the dashboard and noticed that the car was in 'B' mode. I mentioned that to the manager and he noted it as well. I must have bumped it somehow while driving as I NEVER use B mode for anything ... ever. I said I wondered if that was the reason, and put it in D, and lo and behold, the cruise worked again.

    I haven't checked the manual yet to see if this is stated there, but just wanted to let you guys and gals know that the cruise control is inoperative if the car is in B mode. Or at least it seems that that is the case. Other than the car being in B mode, it acted just like it always does, and since I was on the highway, I never noticed the braking effect that B mode gives you.

    Did anybody else realize this ?

    REV
     
    #1 revhigh, Jun 15, 2011
  2. Paradox

    Paradox Prius Enthusiast / Moderator
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    There was a post about this not too long ago, but hey glad you found it out for yourself. It makes it more fun that way :)
     
    #2 Paradox, Jun 15, 2011
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  3. cwerdna

    cwerdna Senior Member

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    Yes. My mom "discovered" that for me in my 2nd gen when she somehow was driving in B mode and couldn't enable cruise.

    It's in the manual AFAIK and there've been a few threads on PC about it, at least for the 3rd gen.
     
    #3 cwerdna, Jun 15, 2011
  4. revhigh

    revhigh MPG Enthusiast

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    I must have missed those posts.

    Just wanted to let you know if it happens to anyone else. :D

    The manual says that the shift lever should be in D, but doesn't specifically mention that it's disabled in B, at least that's all I could find.

    REV
     
    #4 revhigh, Jun 15, 2011
  5. energyandair

    energyandair Active Member

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    IIRC, cruise control applies engine breaking when you are going downhill and regen breaking is insufficient to control the speed.

    This works well on long constant speed descents but not when you have to change speed a lot (eg bends). For long variable speed descents you are better off in B mode.
     
    #5 energyandair, Jun 15, 2011
  6. ItsNotAboutTheMoney

    ItsNotAboutTheMoney EditProfOptInfoCustomUser Title

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    No, I didn't, but the manual says:

    Cruise control can be set when
    - The shift lever is in “D”.
    - Vehicle speed is more than approximately 25 mph (40 km/h).

    Also it says:

    Situations unsuitable for cruise control
    Do not use cruise control in any of the following situations.
    Doing so may result in control of the vehicle being lost and could cause an
    accident resulting in death or serious injury.
    ...
    - On steep hills
    Vehicle speed may exceed the set speed when driving down a steep hill.
    ...

    Given that B mode is expected to be used on steep hills, it makes sense that they'd drop out of cruise if you knocked it into B as well.

    I haven't put it into B, but my wife did accidentally hit the Park button while I was driving. The car beeped and my wife mentioned she hit Park. Fortunately I realized it could have an effect, glanced at the display, saw it was in N and put it back into D. I think we were doing between 40 and 50 so no harm done to the HSD.
     
    #6 ItsNotAboutTheMoney, Jun 15, 2011
  7. spiderman

    spiderman wretched

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    I am more interested in how you got into "B" twice without noticing.
     
    #7 spiderman, Jun 15, 2011
  8. revhigh

    revhigh MPG Enthusiast

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    No idea ... unless I accidentally put it in B (instead of D) when I got in the car right from P, and since I accelerated onto the highway and maintained a steady speed just didn't notice the braking effect.

    As I said ... it happened twice in about 9000 miles that I'm aware of.

    REV
     
    #8 revhigh, Jun 15, 2011
  9. qbee42

    qbee42 My other car is a boat

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    Yes. Next question?

    Tom
     
    #9 qbee42, Jun 15, 2011
  10. Teakwood

    Teakwood Member

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    Sorry, Bud, but it was one of my first lessons-learned. :(
    I guess you may have rested your hand on the shifter at some point. I live up a hill, and use "B" every time I leave home. Occasionally, I forget to shift back into "D," and then I try CC when I get out on the flats.
    It is always a "Doh" moment for me.:redface:
     
    #10 Teakwood, Jun 16, 2011
  11. theloop82

    theloop82 Member

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    I dont ever use B, because if you are going down a long sustained hill, and you have the cruise control on, the computer will automatically do it for you after the battery is charged. You dont have to touch a thing, and you dont have to remember to take it back out of B when the hill is done.

    The Cruise Control on this car is the best ive ever had.
     
    #11 theloop82, Jun 16, 2011
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  12. revhigh

    revhigh MPG Enthusiast

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    I agree ... I've said that 100 times.

    REV
     
    #12 revhigh, Jun 16, 2011
  13. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    Gen 1 - cruise worked in B mode - great thing at holding your desired speed.
    Gen 2 - cruised stopped working in B mode - had to either let the car get faster and use regen braking (light brake pedal) or B mode + feather the accelerator to reduce the effect.
    Gen 3 - cruise emulates B mode going down hill. Your charge meter will get to 2/3 charge on it's own. Best of both worlds!
     
    #13 HTMLSpinnr, Jun 16, 2011
  14. tomstodola

    tomstodola Member

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    Why would you use "B" (engine braking) to drive normally? I use it to quick charge the battery on downhills or to assist in slowing the car down on steep grades. Your mileage would have to suffer if you drive in this mode for any length of time.

    yeah, the cruise control on the Prius is excellent!
     
    #14 tomstodola, Jun 17, 2011
  15. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    #15 JimboPalmer, Jun 17, 2011
  16. SpikeVFR

    SpikeVFR New Member

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    Yes since B is meant to increase drag when going down a hill, you would not want cruise control on, since if you need to press the gas to obtain a wanted speed, you shouldn't be in B anyway.

     
    #16 SpikeVFR, Jun 17, 2011
  17. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    Not necessarily - on a steeper incline, you may want to regulate the amount of resistance to maintain a speed if engine/regen drag is sufficient to keep the vehicle from over-speeding.

    That said, the 3rd gen CC has that all taken care of!
     
    #17 HTMLSpinnr, Jun 18, 2011
  18. twittel

    twittel Senior Member

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    I agree. Sometimes, I use cruise in lieu of the accelerator.
     
    #18 twittel, Jun 18, 2011
  19. ItsNotAboutTheMoney

    ItsNotAboutTheMoney EditProfOptInfoCustomUser Title

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    Funny, I don't speed back up using the cruise because I think it's way too aggressive.
     
    #19 ItsNotAboutTheMoney, Jun 18, 2011
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  20. SpikeVFR

    SpikeVFR New Member

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    Not sure what yu mean here, yes B increases drag and charges battery more rapidly, thus slowing vehicle down to keep from going faster than you want to, or having to brake.

     
    #20 SpikeVFR, Jun 20, 2011
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