Repost from Reddit; and then a question

Discussion in 'Gen 5 Prius Technical Discussion' started by Paul Gregory, Jul 19, 2025 at 9:43 PM.

  1. Paul Gregory

    Paul Gregory Senior Member

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    Be careful putting your Prius in neutral!
    Well, I got a Prius Prime 2021 a few months ago, and was definitely the idiot driver today trying to put my Prius in neutral at the automatic car wash today.

    First time at one of these car washes, but it seemed pretty obvious I could see the car in front of me go in neutral and get pulled along. So I rolled up hoping I'd feel the tow engage, and all would be good.

    I thought I'd put my car in neutral, but it seemed to be moving too fast. Fortunately I hit the breaks before slamming into the car in front of me.

    Then, per the exasperated employee's instruction, I put the car in reverse to reengage the tow, and once again nearly slammed into the car behind me, twice. The employee at the wash kept telling me what I already knew, put it in neutral, foot off the break, and let it go.

    Finally, we both realized, I was not in neutral. Each time I'd attempted to put the car in neutral, I wasn't holding the shifter in position for long enough for neutral to engage (it takes like 3 seconds).

    Just a warning to all you Prius owners out there. I was able to narrowly avoid several accidents, but it was a very embarrassing experience all around and hope no one else will have this experience.

    I assume this is some sort of safely mechanism to prevent drivers from accidentally putting the vehicle in neutral when shifting to drive or reverse. But for anyone used to a standard transmission this feels like a very unintuitive design, if I pull the shifter straight out and release it should go into neutral no matter what.

    Love everything else about the car so far though, so I suppose there will always be drawbacks with any car.

    Question: If it was truly going into neutral (not just freewheeling the transmission) Why should it do anything but simply disengage all power from the wheels? That 3 second delay and sudden lurch cast doubt on that theory. And here's the curious part: suppose the gas engine is running at 2000 RPM while you shift into neutral, Wouldn't there have to be a similar amount of reverse rotation of the electric drive motor? How could this happen without some active monitoring and control of the drive wheels?

    Perhaps the car in the posting had no active control over the drive wheels when shifting to neutral, but my experience in car washes and elsewhere has been that there is no lurching at all. In either my gen 3 or my gen 5.
     
  2. ChapmanF

    ChapmanF Senior Member

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    This appears to have been the source: archived Reddit post

    You've posted questions about neutral at length in other threads, and repeated some of them here, but conveniently for this thread, no more than the first seven words of your question are needed to answer it.

    As a quick review of the reposted reddit post confirms: the car was not going into neutral. Not 'truly' going into neutral, not falsely going into neutral, not in any other way going into neutral. You move the shifter left and hold it to select neutral, and the driver didn't do that, so neutral wasn't selected.

    Here's that text again.

    The car went forward in the first paragraph, because it had already been in D, and then the driver didn't select N, so the car was in D, and went forward.

    The car went backward in the second paragraph because the driver had shifted to R "to reengage the tow", and then didn't select N, so the car was in R, and went backward.

    Finally, in the third paragraph, they remembered how to select N, and when they did that, the car rolled freely with the tow just like yours or mine does in N.


    For what it's worth, I think the Reddit poster exaggerated the length of time you need to hold the shifter left to select N. I have never put a stopwatch on it, but I think it is much closer to 1 second than 3.

    Amusingly, the exact wording in my 2010 owners' manual is Keep the shift lever in "N" for a while after you shift it to that position.

    So now we know the precise answer: a while.
     
    #2 ChapmanF, Jul 19, 2025 at 10:28 PM
    Last edited: Jul 19, 2025 at 10:45 PM
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  3. Paul Gregory

    Paul Gregory Senior Member

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    Of course this brings out the trolls who are here to obfuscate the issue and create conflict.
    Never mind trying to engage the topic, just deny and ignore the important points to prolong the conflict.
    After all, conflict is their only goal.

    But for those who want to engage this topic in good faith, here it is: If "neutral" were just simply freewheeling of the transmission, there would be a rather noticeable "bump" in the drivetrain when the wheels have to bring the idle transmission geartrain up to speed very quickly (and in reverse). I have shifted to neutral many times, and never felt any sort of a lurch or a bump, even when traveling at speed. This would not be possible of the laws of physics are still in effect. There must be an interval where the traction control computer operates the electric motors to achieve a smooth syncing of the two power sources with the wheels. My car has never made any noticeable bumps or lurches. This convinces me that the computer is actively engaged, not just "freewheeling the transmission."
     
  4. ChapmanF

    ChapmanF Senior Member

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    It would be great for a few readers who have come this far to comment on whether post #2 or post #3 seems more on-topic to explain the story the Reddit poster told.
     
  5. Paul Gregory

    Paul Gregory Senior Member

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    If you were earnestly trying to deal with this issue, you'd address the facts of it, instead of constantly trying to dismiss and deny them.
     
  6. ChapmanF

    ChapmanF Senior Member

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    The only 'issue' raised in this thread—the whole point of the reddit post you found—is to remind people that you haven't shifted to N unless you held the shifter there long enough to see N on the dash.

    So if you were in D, and you haven't shifted to N, you're in D still, and might be surprised that the car still goes forward.

    And if you were in R, and you haven't shifted to N, you're in R still, and might be surprised that the car still goes backward.

    The reddit poster finally remembered how to shift to N and the problem was solved, and the post doesn't even go on to say anything about how the car behaved once it was shifted to N. The poster just moved right on to commenting on the unintuitive design, but otherwise loving the car.

    We can infer the car just rolled nicely through the car wash in N the same way it has for everybody else who's taken a Prius through a car wash. If anything else had happened, the reddit post probably would have said so,

    So, in other threads, I've seen you trying to draw conclusions about how neutral works from various stories and observations.

    What's interesting and different about this thread is you're trying to draw conclusions about how neutral works from a reddit post that doesn't say one word about anything that happened after shifting to neutral.

    Seems ambitious.
     
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  7. Paul Gregory

    Paul Gregory Senior Member

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    Once again, the whole point of my post is being ignored, just to make it look like I don't understand it.
    When the whole point is to generate conflict, this makes sense, I suppose.

    It seems apparent that the Reddit poster was not able to shift into neutral quickly (as would be the case if it simply let the drivetrain freewheel). There is obviously a delay, which belies that something else is going on.
    It indicates that the computer needs some time to calculate how to achieve zero torque on the wheels, especially when the gas engine is running. Remember, the drive wheels never disconnect from either power source.

    I'd be happy to be proved wrong with facts, but so far, all my facts are being ignored or dismissed, and nothing has taken their place.
     
    #7 Paul Gregory, Jul 20, 2025 at 10:25 AM
    Last edited: Jul 20, 2025 at 10:47 AM
  8. Mendel Leisk

    Mendel Leisk MMX GEN III

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    It takes about a second of pressing the shifter in the 9 o’clock direction to get into Neutral.
    Seriously man, I think you have “issues”. Sometimes the toughest thing to see is yourself. I’m not trying to talk down; I’ve been there.
     
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  9. Paul Gregory

    Paul Gregory Senior Member

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    This is not about me, feeling like a protagonist against a consensus; it's simply an issue that the consensus fails to resolve, either by ignoring/dismissing it, or just simply trolling for online combat.
     
  10. Paul Gregory

    Paul Gregory Senior Member

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    What a sad world it would be if everyone let the consensus do all their thinking.
    Wait, it is that way.
     
  11. Paul Gregory

    Paul Gregory Senior Member

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    You're definitely somewhere.
     
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  12. Paul Gregory

    Paul Gregory Senior Member

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    Most of what you say makes sense, but this doesn't. You are implying that I have issues because I won't go along with the consensus. It's not a world-changing problem, but it's not been resolved, even by the consensus. The consensus is irrelevant to the problem being resolved.
     
  13. Paul Gregory

    Paul Gregory Senior Member

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    So the consensus can't be wrong?
     
  14. ChapmanF

    ChapmanF Senior Member

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    You seem to think that the delay in selecting N is something besides a matter of user-interface design.

    The shifter design ever since gen 2 has been a spring-return, purely electronic input device to an ECU, where the lever has to go through the 'N' position every time you shift to D or R, and again every time you release it after shifting to D or R. So they wrote the firmware to not recognize a selection of N unless you hold the lever there for a moment.

    As soon as you have held it long enough for N to light on the dash, the mode changes immediately to N. The actual change of mode is not where any delay happens.

    The user interface in gen 1 was different: they used a conventional lever that stayed put at each different position. That firmware did not impose any N delay. The instant you put the lever in the N position, you were in N.

    And yet the gen 1 powertrain works just the same way as the later gens (other than having a higher-voltage battery and no boost converter).


    You've now used 'consensus' in a couple different ways.

    You've often used it to mean a consensus understanding about how N works.

    My post #4 was a simple reading-comprehension check to find out if it's just me or if other people also notice that the reddit post was only about how to select N, and not about any behavior occurring in N.

    That wouldn't be referring to any kind of pre-established consensus, but only to any consensus that might form, among comprehending readers, as to what the reddit post even says.

    Sure, you might cast doubt on even that consensus, too. Go for it. It might still be better than just having two members going "is not" Is too".
     
    #14 ChapmanF, Jul 20, 2025 at 12:51 PM
    Last edited: Jul 20, 2025 at 1:00 PM
  15. Paul Gregory

    Paul Gregory Senior Member

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    May I disagree with your explanation, without upsetting the "consensus?"
    I get nothing from being the odd man out, but I need to settle the question in my mind with evidence.
     
  16. ChapmanF

    ChapmanF Senior Member

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    Which 'consensus' do you mean this time?

    About how N works?

    Or about what the reddit post says?

    Or about something else?
     
  17. Paul Gregory

    Paul Gregory Senior Member

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    You say that "neutral" is just freewheeling gears.
    I say that doesn't wash for me, as I have explained many times.
    I believe the traction control system is actively involved.
    Who may agree or disagree with whom doesn't really figure into it.
     
  18. bisco

    bisco cookie crumbler

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    is there the possibility that the reddit poster is/was confused?

    i can and have replicated his actions with no issues in 3 different pri.
     
  19. ChapmanF

    ChapmanF Senior Member

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    I think the reddit poster exaggerated the time delay for selecting N. I think it's closer to 1 second than it is to 3 seconds. The poster was flustered in front of a car wash attendant and probably 1 second felt like 3 at the time.

    There isn't anything else unusual reported in that post. Yes, if you shift to D, and then you don't shift to N, you go forward. And if you shift to R, and then you don't shift to N, you go backward.

    Nothing about that is at all unusual, or at all hard to replicate, or even particularly interesting.
     
  20. bisco

    bisco cookie crumbler

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    also, if your foot is on the brake (where it should be when shifting) you're not going to crash into the guy in front of you. unless your washing while impaired (which may include a lot of reddit users)