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Putting it in park, or longpress for (P) - what's the difference?

Discussion in 'Model S' started by Ande, Aug 26, 2017.

  1. Ande

    Ande Member

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    P90D , I would assume "Park" (single short press) - mechanically locks bort front and rear wheels ? (but what about the differntial, in case of winter/icy parking)

    It's also possible to press and hold the park button for (P) - which I assume operates the smaller, grey calipers.

    How does it work, and when would one prefer one method over the other, and why.
     
  2. Ande

    Ande Member

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    (bort=both - unable to edit for some reason)
     
  3. boaterva

    boaterva Supporting Member

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    The S manual says the parking brake is only on the rear wheels... have we seen different for the gray calipers (the separate parking brakes)?

    What other parking brake method is there besides the button on the end of the shift stalk?
     
  4. HankLloydRight

    HankLloydRight Fluxing

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    AFAIK, the parking button only engages the small rear calipers. No differential lock. That's it.
     
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  5. whitecotton

    whitecotton Member

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    Parking brake on S and X is the two small calipers, one on each rear wheel. The front wheels have no locking mechanism.
     
  6. boaterva

    boaterva Supporting Member

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    And something that may be useful to people... how to manually disengage the parking brake calipers if your electrical system fails, so you can roll the car onto a tow truck! A major problem that James Cooke had, and here's the other James, of James and Kate, to show how to release the brakes:

     
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  7. Ande

    Ande Member

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    So far, there is no clear answer.
    it seems those grey calipers are the (P) brakes. - on rear wheels only.
    in what way are they better/safer than the normal "park" ? - the differential could be one reason, (when parking on a slippery surface.)
    do we know for sure that the front wheels does not lock in ?
     
  8. boaterva

    boaterva Supporting Member

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    What normal Park? What other park is there? Please tell us how *you* put the car into park. :D
     
  9. jjh1234

    jjh1234 Member

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    I just tried wait the OP talked about. When I do a short press of the P button, I get the standard P indication in the P R N D display at the bottom right corner of the instrument cluster. When I do a long press (a couple of seconds) of the P button, I get an additional red (P) indication on the top right corner of the instrument cluster as well as the normal P R N D indication. I'm not sure what the difference is and that's what I believe the OP is asking as well.
     
  10. boaterva

    boaterva Supporting Member

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    Well, one is supposed to unlock doors and all that. Does one do that and not the other? Doesn't a double tap do the door unlock if enabled? Is that the same as a long press?

    The manual says whenever in park, the parking brakes are applied. Touch Park (the button) again to unlock doors...
     
  11. jjh1234

    jjh1234 Member

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    I'll have to check. I know I just enabled "Door Unlock on Park" or whatever it's called yesterday and it seems to unlock on the standard short press. I've never heard of a double short press. Maybe that unlocks the doors if "Door Unlock on Park" is disabled?
     
  12. boaterva

    boaterva Supporting Member

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    Interesting idea. The manual says the 'P in parens' symbol means the parking brake is on. I have no idea what pressing the button and NOT getting that means, as it says when you press it once, you are in Park.

    I see the confusion, as you would think you would always get the rear (only) parking brakes applied. Can't think this is different for European builds?
     
  13. spottyq

    spottyq Member

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    #13 spottyq, Aug 27, 2017
    Last edited: Aug 27, 2017
    I am pretty sure there is no difference when the car is stopped (except for the extra red 'P'; in practice only the rear parking brake calipers engage).

    But the difference is when you try to do that while driving (in D, above a certain speed) : a short click or flick of the stalk should put the car in N (plus it will probably beep angrily at you) while a long press would actually engage the rear parking brake calipers; to be used as emergency brakes.

    This is all straight from my head (to take with a grain of salt), but should be easy to test for anyone wanting a final answer. :)
     
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  14. HankLloydRight

    HankLloydRight Fluxing

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    From the Model S manual:

    upload_2017-8-27_12-30-53.png
     
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  15. HankLloydRight

    HankLloydRight Fluxing

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    #15 HankLloydRight, Aug 27, 2017
    Last edited: Aug 27, 2017
    There is no differential lock. You keep mentioning a slippery surface -- how is locking both rear wheels with calipers any different from a differential lock (if one existed?)

    Yes*

    *EDIT: For cars with the rear parking brake calipers. It's possible the front brakes do lock for newer cars without the rear brake parking calipers. I don't have one of those, so I don't know for sure.
     
  16. GaryREM

    GaryREM Member

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    Don't for get that newer cars don't have the parking brake caliper.

    It was originally needed because the brakes were hydraulic only.
     
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  17. Ande

    Ande Member

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  18. HankLloydRight

    HankLloydRight Fluxing

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    Ok, you made it sound like a differential lock on ice would be better than a brake caliper lock.

    Also, the differential in the Tesla is a simple differential, not a LSD. So if there was a diff lock, it would lock up both wheels anyway.
     
  19. boaterva

    boaterva Supporting Member

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    So newer (what's newer?) only have one caliper on each wheel? I'll have to check this out when I get a chance to look at current cars, first I've heard of this. I thought they all had the separate ones so one pair was locked when in Park and the others were completely independent.
     
  20. jjh1234

    jjh1234 Member

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    Ok, I just did some more testing with the loaner MX75D I have. It was made on 5/17.

    It does NOT have the extra little caliper on the rear wheels (or the front for that matter), whereas my 11/16 MS75D does. I'm not sure if that's a MS / MX thing, or a manufacture date thing. However, I still hear the whirring noise while applying and releasing the parking brake like the models that have the extra caliper in the back. From that, I assume the actuator has been built into the main caliper now.

    With a short press of the Park button the P is activated on the P R N D display. If I press the Park button again and hold it for a couple of seconds, I hear a short whir from the rear calipers and the red (P) comes on as well. I believe the parking brake is bring applied with a little extra torque. If true, I see this as useful when parked on a steep hill, especially with a trailer.

    With two quick short presses, the automatic parking mode is activated and I am prompted to pick a parking direction and exit the car.

    With a short press then a second short press a few seconds later, the doors are unlocked if the "Door unlock in Park" is disabled. Otherwise the doors are unlocked on the first press when the "Door unlock in Park" is enabled.

    Also, on another note, this MX75D seems just as fast as the MS75 made in 7/17 I had yesterday that had the speed upgrade. This does seem to validate the pre-July loaners and demo units have been upgraded to the faster acceleration. I will post in the other thread as well.
     
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