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Tesla in Park suddenly moved forward [air temp 33, snow on ground, parked on incline, OEM tires]

Discussion in 'Model 3' started by bradyb23, Nov 26, 2019.

  1. bradyb23

    bradyb23 Member

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    Good evening folks. I know this will sound nuts, but I recently leased a new 2019 Tesla Model 3 long range. The car is amazing. I leased it in central CA where we don't have much weather, and other than a few odd issues that have all be explained and/or resolved, I took it on a road trip to southern Oregon. Today, it snowed pretty heavily. The car ran amazingly well on the messy roads, but this evening at about 4:25 pm PT I parked it in a parking space at the theater that had maybe a 3 or 4% incline. I backed the car in and the tires spun a little as I tried to get all the way up into the spot, but I felt in control the entire time. When I was in the spot, I put the car in P and put on the parking brake, and exited the vehicle. As I was exiting -- and as my 12 year old son was exiting the front passenger seat, the car started to roll forward. At first I thought it might be sliding (which shouldn't happen, but it was snowy), but as I jumped into the car in a panic I swear the wheels were turning. I looked at the display and clearly saw the P and the red Parking Brake symbol, as did an adult riding in the rear. I estimate the car moved a good 12 inches and would have continued rolling had I not jumped in and manually pressed the brakes. I put the car into reverse, backed up again, and again put the car into P with the Parking Brake on. Everything seemed fine, and so I had my passengers exit the vehicle again. My son got out this time without an issue, but when the passenger on the right rear exited, the same thing happened (no foot on the brake; car clearly in P with the red Parking Brake symbol on). I immediately hit the brake, had everyone exit, and then moved the car to a different parking spot. Obviously, this is very alarming. I can't believe it's a defect with the car, but has anyone had a similar situation? Outside air temp was about 33, and the snow on the ground was very slushy, not at all icy. I tried to see if my cameras caught the event, but I don't think they did. I also watched as an SUV parked in the same spot I was in and they drove in, parked, got out, and went on their way with not so much as a pause. Any ideas?
     
  2. derotam

    derotam Member

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    Wheels spun as you backed into the spot...sounds like the car was sliding. My money is with the car sliding on the clearly slippery parking space. It stopping when you pressed the brake was due to the fact that the parking brake is only on the rear so the front wheels did not resist any of the slide. When you pressed on the brake the front wheel brakes activated, stopping the rotation.
     
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  3. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    Snow in Oregon is often extremely slippery - the temperature near freezing often results in some of the worst winter conditions (in terms of traction) one can encounter. See post above for the explanation of the observed behavior. It’s not a good idea to park on a significant incline in these conditions.
     
  4. mswlogo

    mswlogo Well-Known Member

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    Rear wheel slipped and front ones rolled.

    OEM tires are horrible in snow. Get some appropriate tires.
     
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  5. ngogas

    ngogas Active Member

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    Sound like a ice and snow scenario.
     
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  6. Quantumbuc

    Quantumbuc New Member

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    I can confirm the exact same thing happened to me today. I was searching online to see if anyone else had an issue like this.

    My driveway is on an incline. I back into it every day so my car is facing downhill. It is snowing today, and I backed in and put it in park. After I took my foot off the brake, one or two seconds passed, then it rolled forward about two feet and then stopped. Really spooked me. I did it 3 more times, and each time the same thing happened. I rebooted the car to make sure it wasn't a glitch, but that didn't help. I had my wife watch to make sure the wheels were rolling as opposed to the car just sliding. It was always the same... park, foot off the brake, pause, pause, roll, stop. The pause before the roll forward was the most distressing, as I normally just get out of the car. I just happened to wait because I was putting on gloves.

    Very strange.
     
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  7. C141medic

    C141medic Active Member

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    Strange indeed. Definitely not normal behavior. Once you place in Park, the car shouldn’t be going anywhere. Obviously ice is a different issue, especially if you’re on an incline. Wonder if this is related in any way to the new update with hold mode where some people have reported the vehicle rolling backwards momentarily on inclines?
     
  8. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    Sounds like your parking brake is not working. You should hear it actuate, and when it does the rear wheels will not turn. If it is released you would hear it. Definitely you must have this addressed immediately. (Your wife is 100% sure the REAR wheels were turning? - the fronts would still roll - there is no brake on them...)

    This is a big problem - I'm not sure what other mechanism there is to prevent the car from rolling when it is parked (there may be one, just not sure how it works). In any case it is a safety issue regardless of whether there is another mechanism.

    Let us know what you find out. I suspect that the front wheels are rolling while the rears slide (because you reported that it is snowing) but it could also be a horrible failure.
     
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  9. Victoria3

    Victoria3 Member

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    You parking brake only locks the rear wheels, while the foot brake does all 4. If you are in slippery conditions once you put it in park and release the brake the car has lost 50% of its traction...if the rears slide the front will roll.
     
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  10. N54TT

    N54TT Member

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    did you get a video of this? That would be the best way to definitively know if the rear wheels are indeed rolling and not slipping....and to show tesla what is happening.
     
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  11. Quantumbuc

    Quantumbuc New Member

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    My wife is now recanting her testimony and telling me that she only saw the front wheels spinning. She no longer recalls if she was watching the rear wheels. The next morning, the ice had melted and I could no longer replicate it. Yes, I should have definitely videoed it.

    I am going to guess it is as people surmised. Once I put it in park and took my foot off the brake, after a slight delay the front wheels released and the car slid. A good lesson for icy weather I hadn't had to think about before.
     
  12. DiscordianDave

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    I have just had an occurrence of exactly this today. My Model 3 was parked on my driveway, me and the kids got out of the car, and a few minutes later it slid down the driveway onto the road by itself. After noticing that the car was on the road rather than in the driveway where I had left it, I moved it back into the driveway and went to get the shovel to clear some of the snow (I had not yet shoveled the driveway this morning) - as I was getting the shovel, the car started sliding again and I noticed that the rear wheels were locked and the front wheels were moving, which matches behavior described up-thread. I am in the Toronto area with OEM tires, and I apparently purchased a self-driving toboggan.

    I've attached an image of the pattern which was left on the driveway by the tires - you can see the clear difference where there are tire treads on part and a smooth line on the others (that was the locked rear wheel sliding):
    IMG_20191206_124509.jpg
     
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  13. TSLA Pilot

    TSLA Pilot Active Member

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    I have a hard time believing that the state of wisdom and scientific knowledge is such that people are not aware that the parking brake works on only ONE set of the wheels (the rear wheels) while the foot brake works on all four, and that snow and ice have a low coefficient of friction.

    But this appears to be the case.

    Tips:

    1. If it is slippery and you've parked on a slope, your car may slide downhill. Park elsewhere or block the front wheels with chocks.

    2. If you often drive in ice and snow, get snow tires.

    3. Turn your steering wheel so as to ensure you car will slide into the curb if it slides (which is AWAY from the curb when parked facing uphill; TOWARD the curb when facing downhill).
     
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  14. DiscordianDave

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    There's always somebody on the Internet that feels that they need to respond to a post like this by reciting the manual or basic troubleshooting tips, in order to blame the original poster and make them feel like an idiot. It's common to software forums and car forums alike it seems.

    Suffice it to say that in my history of owning and driving several vehicles on this driveway over a series of many many years, and having lived my entire life in northern snowy climates, this is the first time that I have ever encountered such an issue.
     
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  15. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    #15 AlanSubie4Life, Dec 6, 2019
    Last edited: Dec 6, 2019
    I assume the issue would also occur with a RWD ICE vehicle. But probably you have not had one of those in that driveway? Definitely this is something that might take many people by surprise, since RWD vehicles do tend to be more rare.

    A bit more charitable explanation would be that people in snowy climates probably get it in their mind that their AWD vehicle (which is probably the predominant Model 3 vehicle in these climates) will behave similarly to their previous AWD or FWD vehicles in this situation. But the Tesla Model 3, when turned off, behaves like a RWD vehicle - the front wheels are free to roll when the car is off.
     
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  16. DiscordianDave

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    You are correct, every other vehicle up to this point has been FWD - and I have definitely noticed driving differences in this vehicle due to the RWD (such as not accelerating around a corner in slippery conditions as you would with FWD).

    This feels like the kind of thing that is fixable with a software patch - you could either:

    1. Have an option to engage parking brake on all four wheels (basically use the car's hold mode when parked)

    2. Detect when Park is engaged but the front wheel is beginning to rotate and apply brakes at that time

    I would favour the first option because the second one allows the car to gain a bit of momentum which may then be more difficult for the brakes to overcome once motion has begun, however there may be good reasons that the standard brakes are not applied in park which I am not aware of at the moment.
     
  17. ZOMGVTEK

    ZOMGVTEK Member

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    It may not be possible to have the vehicle apply the hydraulic brakes while the car is still 'sleeping'. And its very likely not possible for the vehicle to monitor the wheel sensors and then apply the hydraulic brakes while the car is asleep. So the trouble is these solutions most likely mean the car must stay awake, and that's a significant drain on the battery. This isn't an issue specific to Tesla, but the stock all season tires are absolute trash in snow. It's not terribly uncommon to have electric parking brakes on the rear tires in modern cars. If anything the Model 3 should fare a bit better with a more rear biased weight distribution than most cars.

    I've had this happen before on FWD vehicles on steep driveways, I was always in the car and testing to see if the parking brake would hold. With a manual transmission you can just leave it in gear and its basically like 4 wheel parking brakes. Although for most automatic transmission vehicles, only 2 tires lock and would behave just the same in the same conditions. Most vehicle manuals do say this is possible. With the stock tires on very smooth ice, it wouldn't take much force for the car to slide even with all 4 tires locked.
     
  18. DiscordianDave

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    In my situation, waiting in the car would have done nothing - the car began to slide 4 minutes after everybody exited the vehicle and we were all well in the house by that time. I have exact times because I caught the whole thing on my Nest camera (I went back and checked to see if I had done something wrong). And my driveway is not particularly steep - I would estimate a 3% grade at most. It's in a suburb of a very flat portion of Ontario (Toronto), it's not hill country.
     
  19. tvad

    tvad Member

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    It's relatively easy to put the Model 3 in Park and neglect to press the stalk button long enough to engage the parking brake. I'm not saying this is what happened...but a failure to engage the parking brake could contribute to the observed behavior.
     
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  20. AlanSubie4Life

    AlanSubie4Life Efficiency Obsessed Member

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    Wait, what? I've never had to do anything other than put the car in Park for the parking brake to actuate (or occasionally (inadvertently - I don't make a habit of it!), I just exit the vehicle without even bothering to take the car out of Drive, and just let the car take care of it itself...). Are you sure there is not something wrong with your car?
     
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