# TACC scary incident!!!



## Tombolian (Sep 27, 2018)

I was driving home from work yesterday when I encountered bumper-to-bumper traffic. After about a mile of manually battling it, I decided to let Ginger have a go at all of the stopping/starting... While the car was rolling along at about 5 MPH, I (very ignorantly) accidentally pressed the right stalk up (perhaps because I 'learned' that pressing up cancels all auto-pilot control if done while driving). What happened as a result scared the poop right out of me and the guy right behind me. Even though the car was rolling forward, it shifted into reverse and abruptly stopped. If the guy behind me was like most drivers and was riding my bumper, there would have been an accident.
My thinking is simple; Shouldn't the car only shift into reverse if the speed is zero? If left this way, I can only assume there will be more Teslas needing new rear-ends. What do y'all think? (no, I'm not using creep mode)


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## Flashgj (Oct 11, 2018)

The manual states:

You can only shift into Reverse when Model 3 is stopped or moving less than 5 mph (8 km/h). If moving less than 1 mph (1.6 km/h), you must press the brake.

You must have been going 5 mph or less and pressed up too far.


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## BlueMeanie (Aug 20, 2018)

Cancelling TACC only requires a 1/2 click up, which wouldn't put it in reverse. 
But, I agree with you that Tesla should set the speed to less than like 1 or 2 MPG to go into reverse!


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## Flashgj (Oct 11, 2018)

BlueMeanie said:


> Cancelling TACC only requires a 1/2 click up, which wouldn't put it in reverse.
> But, I agree with you that Tesla should set the speed to less than like 1 or 2 MPG to go into reverse!


I would have to agree, can't personally think of any reason why I would want to shift into reverse while going 3-5 MPH.


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## Tombolian (Sep 27, 2018)

Flashgj said:


> The manual states:
> 
> You can only shift into Reverse when Model 3 is stopped or moving less than 5 mph (8 km/h). If moving less than 1 mph (1.6 km/h), you must press the brake.
> 
> You must have been going 5 mph or less and pressed up too far.


What?!?!? I'm expected to read the manual??? (jk) Great find, thank you for pointing this out for me.


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## Tombolian (Sep 27, 2018)

BlueMeanie said:


> Cancelling TACC only requires a 1/2 click up, which wouldn't put it in reverse.
> But, I agree with you that Tesla should set the speed to less than like 1 or 2 MPG to go into reverse!


Excellent, I think I can work with that, training myself to only do the 1/2 click... I'm amazed how much there is to learn with this car! (but I love it!)


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## Tombolian (Sep 27, 2018)

Flashgj said:


> I would have to agree, can't personally think of any reason why I would want to shift into reverse while going 3-5 MPH.


So far, nobody has presented a good reason to shift into reverse when going 3-5 MPH. I'm new at this, is there a way to submit this to R&D for review? (should I just tweet Elon directly?)


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## babula (Aug 26, 2018)

I actually do this all the time (not in traffic ) and I enjoy it. While going <5MPH I switch between P and D or the other way around and quickly maneuver around.

Good example - driving slowly and doing a 3 point turn.


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## JWardell (May 9, 2016)

I now shift into reverse while still moving forward all the time, I'm glad we have the feature!
But at first since I considered it like an automatic ICE car, I assumed we must waste the time and effort of braking to a stop then changing gears.
I'm too used to driving a manual a and toggling between forward and reverse in any direction whenever I want, and feathering the clutch. Coming to a full stop is such a waste of time and effort when making multi-point turns!

But I will agree that it is dangerously confusing that disabling cruise control and shifting to reverse are the exact same physical action and now depend on the driver to keep track on the situation they are in.


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## Maynerd (Mar 17, 2018)

Would the car even allow you to reverse into a car behind you, wouldn't the obstacle detection stop you?


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## garsh (Apr 4, 2016)

Maynerd said:


> Would the car even allow you to reverse into a car behind you, wouldn't the obstacle detection stop you?


The obstacle detection may slow you down, but it will not prevent a collision if you keep your foot on the accelerator.


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## JWardell (May 9, 2016)

Maynerd said:


> Would the car even allow you to reverse into a car behind you, wouldn't the obstacle detection stop you?


Probably...right now obstacle detection just reduces acceleration if an object is in front of the car. I do truly hope one day Tesla makes the car avoid touching any object in any situation, without an on-screen override.


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## GDN (Oct 30, 2017)

I would agree with others, I'm perfectly OK shifting from one direction to the other at slow speeds without having to use the brake and come to a complete stop, another wonderful thing about electric engines and the drive units. 

I find this related, you may think it totally off topic, but there is a lot of heavy machinery that does this as well. Makes maneuvering and driving much easier. Many of them are hydrostatic drive, you can go from one direction to another with no thought. One model of the John Deere tractor transmission has what is called a left hand reverser. If you are baling hay and need to stop/back up to dump a bale out, hit it, the tractor will slow and change directions, hit it again, will change directions again (and for any of you that know you don't have to back up with the newer balers as it will kick the bale of hay out for you and you don't have to change directions at all.) The point is many types of machinery will let you change directions without having to stop.

However, I'll close with the reiteration, and you already know this now, you executed a maneuver to put it in reverse, not just disengage TACC as you intended. No bug, no need to report to Tesla. Just part of adapting to learn to drive a car that is revolutionizing and changing the way we drive.


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## Tombolian (Sep 27, 2018)

Maynerd said:


> Would the car even allow you to reverse into a car behind you, wouldn't the obstacle detection stop you?


It's not the going in reverse that becomes a problem, it's the sudden stop that I encountered that could potentially cause the car behind me to hit me (if he's not paying attention).
I think I need to experience the behavior of a 3-point turn to see if the points above make sense to me. I'm not sure why my car stopped so abruptly (5MPH to 0 in 0 seconds flat), unless perhaps I had my foot on the accelerator just a little.


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## Rich M (Jul 28, 2017)

Tombolian said:


> Excellent, I think I can work with that, training myself to only do the 1/2 click... I'm amazed how much there is to learn with this car! (but I love it!)


The same goes for engaging autopilot. You only need to double-tap down to the first detent.


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## Rich M (Jul 28, 2017)

Tombolian said:


> I had my foot on the accelerator


That is why you stopped.


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## Tombolian (Sep 27, 2018)

GDN said:


> Just part of adapting to learn to drive a car that is revolutionizing and changing the way we drive.


Agreed, there is a lot to learn about how to drive these things, but at the same time, they could be made idiot-proof and still be just as good. As other's have stated, having two completely different functions on the same stick is probably not the best design, but I can now tell from the feedback, there would be no traction on my request. Consider me a new driver-in-training (again).


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## Tombolian (Sep 27, 2018)

Rich M said:


> That is why you stopped.


An even dumber reason to allow the car to shift into reverse when rolling forward with your foot on the accelerator. Very bad for the drivetrain components. I know that you can do similar stupid stuff in ICE cars but this is supposed to be better than an ICE car. This can be fixed with software. I'm genuinely back on the fence...


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## GDN (Oct 30, 2017)

Tombolian said:


> Agreed, there is a lot to learn about how to drive these things, but at the same time, they could be made idiot-proof and still be just as good. As other's have stated, having two completely different functions on the same stick is probably not the best design, but I can now tell from the feedback, there would be no traction on my request. Consider me a new driver-in-training (again).


One of my most frustrating days with the car I was just wanting to move it in the driveway about 5 feet, and this was before summon. I opened the door, sat half way in the seat and tried to put it in gear and back up. It would move about 6 inches and come to an abrupt stop and put itself back in park. Took me a bit to figure it out. We've all done this many times in a traditional vehicle, not with this one. Never figured out exactly, but after reading I assume it was because I wasn't in the seat good, or moved in the seat and it thought I had gotten out, it stopped and put itself in park.

I don' know what it would do moving at speed or a decent speed or even at a stop light and you lean over to get something out of the floor area or back seat and lift out of the seat a little, but this car is trying to look out for all of us in different ways, just ways we aren't used to.


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## Rich M (Jul 28, 2017)

Tombolian said:


> Very bad for the drivetrain components


Nah, there's no shifting at all internally. Going from +5 MPH to -5 MPH is way less force than hard acceleration followed by hard regen


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## JWardell (May 9, 2016)

Tombolian said:


> An even dumber reason to allow the car to shift into reverse when rolling forward with your foot on the accelerator. Very bad for the drivetrain components. I know that you can do similar stupid stuff in ICE cars but this is supposed to be better than an ICE car. This can be fixed with software. I'm genuinely back on the fence...


This is bad in an ICE, which can only turn in one direction, so gears have to chance place and clutches and all sorts of mechanical stuff needs to happen. An electric motor can run in either direction, as can the fixed reduction gear, nothing is being disconnected or moved. You are simply asking for torque in the other direction, which is exactly the same that happens during regen. This is all at less than 5mph as well, so there is very little force. A digitally controlled motor is happy to change direction repeatedly.


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## Tombolian (Sep 27, 2018)

JWardell said:


> This is all at less than 5mph as well, so there is very little force. A digitally controlled motor is happy to change direction repeatedly.


For having such little force, it sure was a startling jarring, but memory is unreliable so, whatever. I'll concede on this point and trust that your experience with electric motors steers me in the right direction. TY.
Bottom line is to learn how to control my stalk better.


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## JWardell (May 9, 2016)

Tombolian said:


> For having such little force, it sure was a startling jarring, but memory is unreliable so, whatever. I'll concede on this point and trust that your experience with electric motors steers me in the right direction. TY.
> Bottom line is to learn how to control my stalk better.


It is _definitely_ surprising to the human driver when the car suddenly goes in the opposite direction you expect it to. I did this a few week ago. I was talking about mechanical force from the perspective of gearing etc. but mentally even a small amount of torque in the opposite direction is surprising. Similar to unattended acceleration where folks in parking lots plow into a store. Our brains are very slow. And without a shifter that stays in a very obvious position, we have to mentally keep track of the last mode we commanded. Human brains are bad at this.


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## Tombolian (Sep 27, 2018)

If I could just close the loop on this... I've practiced putting the car in gear in the opposite direction of motion several times now and, duh, of course it makes sense for things like 3-point turns... no problem as long as you take your foot off the long-and-skinny.
I've gotten much better at engaging/disengaging AP with the single press down/up on the right stalk, so, thank you all!


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