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Autopilot potential serious issue

kirts

Member
Oct 6, 2019
11
7
Cambridge, United Kingdom
Hi all,

I got my model 3 yesterday and I have been pretty impressed by it so far but time will tell.

I had an interesting issue with the autopilot so I'm hoping someone will tell me I have been stupid and didn't use it properly but we will see.

While I was driving I disengaged the autopilot through a sudden steering wheel movement. I heard the sound that it disengaged and I saw the screen that indeed it was the case. However, it was still controlling the speed of the car without any further involvement!

It tried to get me to 70 miles speed as no-one was in-front of me at that moment so pressed the break immediately. When I stopped pressing the break pedal after having reduced it by 30 miles, it started speeding again! This happened 3 times until I had to slam the break to near full halt until it stopped doing it.

My guess is that although the autopilot stopped working, the car was still controlling the speed through some kind of software bug. Any thoughts or similar events?
 

NorfolkMustard

Active Member
Apr 18, 2019
2,215
2,204
M3P w/FSD
Welcome to the forum

There are two 'autopilot' levels

single-tap of stalk = traffic-aware cruise control. Car will travel at the lower of either the max speed you set, or the car in front

double-tap of stalk = all of the above plus auto-steer to keep you in your lane and lane change.

if you disengage out of the second by jerking the wheel, traffic-aware cruise control is still engaged, until you hit the brakes or lift the stalk up
 
  • Informative
Reactions: Rob R

kevuwk

Member
Aug 5, 2019
330
172
UK
You have TACC and lane assist. Lane assist switched off and TACC (cruise control) stayed on. Move your gear select stalk up to disengage it all
 

Asterix187

Member
Oct 7, 2017
733
682
England
You have TACC and lane assist. Lane assist switched off and TACC (cruise control) stayed on. Move your gear select stalk up to disengage it all
Just to add lane assist and auto steer are two different things. Lane assist either warns or pulls you back into lane, autosteer locks you into the centre of the lane.
 

kirts

Member
Oct 6, 2019
11
7
Cambridge, United Kingdom
I see. Thank you for all the replies! I wasn't aware that TACC even existed, never mind that it would still be engaged. That would explain the first case of speed up but I had to press three times the break pedal before it stopped doing that so based on that information it sounds like a bug.
 

NorfolkMustard

Active Member
Apr 18, 2019
2,215
2,204
M3P w/FSD
could you have tapped the right-hand stalk down after braking? contrary to the manual, it only needs a slight tap of the right-stalk to engage TACC (and similarly a slight double-tap to engage auto-steer). Full stalk travel to the bump-stop isn't required.
 

Rooster6655

Active Member
May 3, 2019
1,562
565
UK
I see. Thank you for all the replies! I wasn't aware that TACC even existed, never mind that it would still be engaged. That would explain the first case of speed up but I had to press three times the break pedal before it stopped doing that so based on that information it sounds like a bug.

If you press the brake then both should be disengaged, if not then contact Tesla.
 
  • Like
Reactions: Yev000 and gangzoom

pgkevet

Active Member
Jul 1, 2019
1,476
1,310
mid wales
I would expect the 3 to behave similarly to my S. If I interrupt autosteer with a steering manoeuver then the blue steering wheel symbol turns grey and a msg pops up 'Cruise control will not brake for you' (or something to that effect) and the car will keep trying to reach the speed in the blue speed symbol. Having that binnacle screen in front of the driver makes such little changes easier to spot.
 

mswlogo

Well-Known Member
Aug 27, 2018
6,195
5,343
MA, NH
FAD Functions As Designed.

You broke out of AutoSteer but TACC is still engaged. Completely reflected on the screen.

One click on the lever is TACC
Two clicks on the lever is AP or AutoPilot or AutoSteer (Speed and Steering)

It feels completely natural after a while. You do have to be careful because the Model 3 tracks the road so well you might think it’s Auto Steering when it’s not.

If you override steering it cancels steering, but leaves TACC.
If you override speed (with the brake) it cancels speed and steering.

One click up cancels both as well.

If you override speed with throttle it will return to TACC once you let up on throttle.

Some folks would like a smooth way to cancel auto steering without canceling speed. But it does not exist.

I love how graceful the Model X breaks of AutoSteer compared to the Model 3. Model 3 is always jerky (passengers always startled). Model X is so smooth (passengers would never know except for the chime). Maybe Model X is to smooth.
 

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