Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Phantom braking is the biggest issue with AutoPilot.

Kitfox

Member
Aug 17, 2019
147
100
Vancouver, WA
Notable item:
Just after you encounter severe unexpected braking when TACC is active:
If you have Teslacam, tap the camera icon in the upper right of the screen to save the video. Wait for it to "Ding!" to indicate success, then continue.
Press and release the right steering wheel roller button.
Wait for the voice control prompt noise.
Clearly Say all in one long 'sentence':
Bug report unexpected braking during cruise control

That is all. ^.^

Works best if you connect to WiFi after the drive.
 

bhzmark

Active Member
Jul 21, 2013
3,426
5,167
The difference between old-style cruise control and AP is that matching traffic flow by automatically braking and accelerating was not a feature of old-style cruise control. Therefore, a driver using old-style cruise control knew they were required to brake to avoid rear ending a car in front.

On the other hand, AP is designed to brake and accelerate to follow the flow of traffic. This is a fundamental difference from old-stye cruise control, and it's precisely why a driver using AP should not have to brake or accelerate to overcome the deficiency of the AP system.


Some are Tools. Maybe you are in that group.

Some know how to use tools and recognize their purpose and limitations.
 

SalisburySam

Supporting Member
Aug 11, 2018
262
317
Salisbury, North Carolina
Some know how to use tools and recognize their purpose and limitations.
If the purpose of TACC is to intermittently and without any warning scare the living *sugar* out of passengers, then it is working well to its purpose. In the ongoing phantom braking cases I experience, there is no way to get ahead of the event, just to correct it when it happens. Given that this behavior doesn’t appear to be going away any time soon, I would very much like to see a TACC configuration switch to enable plain old dumb cruise control as desired. I’d use it all the time with passengers and then still be able to also use the rest of the auto-goodies. As it is now, with passengers for their mental well-being I must forego the $8k worth of EAP/FSD automation I paid for. Not pleased.
 

bhzmark

Active Member
Jul 21, 2013
3,426
5,167
If the purpose of TACC is to intermittently and without any warning scare the living *sugar* out of passengers, then it is working well to its purpose. In the ongoing phantom braking cases I experience, there is no way to get ahead of the event, just to correct it when it happens. Given that this behavior doesn’t appear to be going away any time soon, I would very much like to see a TACC configuration switch to enable plain old dumb cruise control as desired. I’d use it all the time with passengers and then still be able to also use the rest of the auto-goodies. As it is now, with passengers for their mental well-being I must forego the $8k worth of EAP/FSD automation I paid for. Not pleased.

If so recurring how many times have you reported it with the oral report feature? My commute involved an overpass that regularly resulted in phantom braking and then after some reports it never does now.

Have you ever reported it? Its easier that typing a post here.

Small price to pay to further reduce risk of another left turning cross traffic semi and an inattentive driver
 

SupraDude

Member
Jun 11, 2019
131
91
Fredericton
If the purpose of TACC is to intermittently and without any warning scare the living *sugar* out of passengers, then it is working well to its purpose. In the ongoing phantom braking cases I experience, there is no way to get ahead of the event, just to correct it when it happens. Given that this behavior doesn’t appear to be going away any time soon, I would very much like to see a TACC configuration switch to enable plain old dumb cruise control as desired. I’d use it all the time with passengers and then still be able to also use the rest of the auto-goodies. As it is now, with passengers for their mental well-being I must forego the $8k worth of EAP/FSD automation I paid for. Not pleased.

I agree, although I'm sure it's valuable for Tesla to get the data to improve if we all have adaptive cruise and AP, personally I'd prefer if we had standard cruise control and AP. If I'm in a comfortable enough situation that I can kick back and let a computer do the thinking for me and I trust it to stay far enough back using adaptive cruise control, why would I not just turn on autopilot? Alternatively, if I'm not using AP it's likely because I'm in a situation where I need to be involved with the driving and in that case, I can adjust the cruise myself if need be. Emergency braking is still working after all.

I'd like to see something like a 3-5 second delay and gradual phase-in for regen in the case that AP or Adaptive cruise disables without driver input. I think that makes sense and I'm a bit surprised it doesn't already work that way.

Not excusing the behavior at all, but it's relevant to note phantom braking is present in most Adaptive Cruise Control systems. We had this issue in other cars, as well. There's at least one class action lawsuit against Honda for this very issue. It's not a Tesla-specific problem. Hopefully Tesla will ultimately sort it out and improve it with an update.

https://www.classlawgroup.com/wp-content/uploads/Honda-CR-V-Automatic-Braking-Lawsuit-Complaint.pdf

the Class Vehicles to fluctuate their highway speed without warning when adaptive cruise control is set, and (3) Class Vehicles alerting drivers to apply brakes immediately although no obstruction is present.

Good to know that others are having this problem and look I've driven a Honda and Toyota with adaptive cruise and lane keep assist, Tesla's system is leaps and bounds ahead. One time the Honda almost pulled me into a ditch due to a change in road lines, I tested my Tesla on the same road and it performed flawlessly. However, the one glaring difference is that Honda and Toyota's systems can be enabled independently from the standard cruise control giving you the option of using them. My fear for Tesla's system would be a novice operator behind the wheel and a spontaneous deactivation of cruise control by the computer. I know what I'm getting into when I activate these systems and that they are in so-called "beta" mode, I'm fine with them skipping a beat and I understand it's what I signed up for but I'd be very worried if I lent my car to my 70-year-old mother and it did it to her with an 18 wheeler following in close proximity. That's a scary thought.
 

Phlier

Bluebird
Jun 12, 2019
1,475
1,847
Utah
Notable item:
Just after you encounter severe unexpected braking when TACC is active:
If you have Teslacam, tap the camera icon in the upper right of the screen to save the video. Wait for it to "Ding!" to indicate success, then continue.
Press and release the right steering wheel roller button.
Wait for the voice control prompt noise.
Clearly Say all in one long 'sentence':
Bug report unexpected braking during cruise control

That is all. ^.^

Works best if you connect to WiFi after the drive.
Love it. We should all be doing this. I know I will be from now on.
 
  • Helpful
Reactions: WilliamG

brobinson

Member
May 23, 2018
621
639
Ohio
I feel like the phantom braking and jerky autopilot stuff was much better on 2019.15, but it has come back much more on the last two revisions.
 

BZM3

Member
Aug 15, 2019
281
124
Somewhere
biggest Phantom braking issue for me is when another car is merging onto the highway from on-ramp. My car will constantly hit the brakes and want the car to go ahead even though the oncoming car is supposed to yield to me.
That's not phantom braking. it's braking for a specific purpose, whether you agree with it or not.
 

camalaio

Active Member
May 28, 2019
1,483
2,086
Vernon, BC, Canada
Notable item:
Just after you encounter severe unexpected braking when TACC is active:
If you have Teslacam, tap the camera icon in the upper right of the screen to save the video. Wait for it to "Ding!" to indicate success, then continue.
Press and release the right steering wheel roller button.
Wait for the voice control prompt noise.
Clearly Say all in one long 'sentence':
Bug report unexpected braking during cruise control

That is all. ^.^

Works best if you connect to WiFi after the drive.

Is this documented somewhere? It's not in the owner's manual and seems to come from forums. When I do this with the car, it behaves exactly as it does when I give it a command it doesn't understand. Are we sure this does something?

Another poster pointed out Tesla, while trying to behave like a software company, fails to behave like a software company by not offering a straightforward or documented way to file bugs for software issues. Even with this voice command thing, it doesn't seem to give any indication a bug report has been filed nor ask for additional context/questions that might be valuable.

...

If I'm in a comfortable enough situation that I can kick back and let a computer do the thinking for me and I trust it to stay far enough back using adaptive cruise control, why would I not just turn on autopilot?

...

Careful there, that may be the same train of thought that put us where we are today :p
"If they're comfortable enough to use cruise, why not have the car do automatic speed and steering control as well? That should be all they ever want."

On my common roads, adaptive cruise is sometimes more suitable than Autosteer. Autosteer's performance around small highways where I live still leaves a lot to be desired, and I'd rather do the steering while using adaptive cruise that works well. Very different inputs.

AP3 must be different than AP2.5 because I rarely get any phantom braking at all now.

I'm on AP3 and get plenty of phantom braking. Shrug.
 

brobinson

Member
May 23, 2018
621
639
Ohio
Yepp, frequent phantom braking is why we don't use cruise. It's a shame, we really wanted adaptive cruise from a new vehicle purchase. My wife gets to drive regular rental vehicles often for work and has never experienced phantom braking in those vehicles that have adaptive cruise (nor the general twitchiness of cruise in the Model 3 of course). It's actually what made her want adaptive cruise on our next vehicle. The Model 3 doesn't have "normal" non-adaptive cruise, so we effectively don't have usable cruise control on our 2019 car. Big bummer.

Over a 50/60km highway trip (typically work day for us), we get probably 3-10 phantom braking events. Some in routine spots (inconsistently though), some random spots. No overpasses here, so it's not that common problem. In some cases, it seems like it doesn't understand cars (especially semis) in opposing traffic are in different lanes going around corners, and slams on the brakes. Other times, it seems unknowable as to what caused it. We've been nearly rear-ended (aggressive tailgating work rush traffic, gotta deal with it), it's just not worth using.

Of course, I can lightly ride the throttle to prevent braking, but then why don't I just... apply throttle without cruise?

EDIT: Ah, yes, as others mentioned, the over-reacting to vehicles slowing down as well. I get this is hard though, human drivers gamble that the vehicle in front will successfully get out of the way and not have to keep slowing down directly in front of them. The Model 3 does not, which is understandable but very annoying.

My wife's VW behaves pretty similarly to my model 3 on TACC, with the exception of braking due to overpasses. Behaviors for vehicles departing lane, entering lanes slowly, cross traffic, etc.. all work almost the exact same as my model 3.
 

camalaio

Active Member
May 28, 2019
1,483
2,086
Vernon, BC, Canada
My wife's VW behaves pretty similarly to my model 3 on TACC, with the exception of braking due to overpasses. Behaviors for vehicles departing lane, entering lanes slowly, cross traffic, etc.. all work almost the exact same as my model 3.

Yes, those are all expected cases for braking. Note how you had explanations for when it occurred, and those are reasonable things to react to in some way.

Phantom braking (no apparent cause, or extremely silly cause like opposing traffic passing by) is the problem at hand.
 

brobinson

Member
May 23, 2018
621
639
Ohio
Yes, those are all expected cases for braking. Note how you had explanations for when it occurred, and those are reasonable things to react to in some way.

Phantom braking (no apparent cause, or extremely silly cause like opposing traffic passing by) is the problem at hand.

Except that there are plenty of people in this thread and others that lump them all together. Its pretty clear that many people don't know what the expected behavior is.
 

camalaio

Active Member
May 28, 2019
1,483
2,086
Vernon, BC, Canada
Except that there are plenty of people in this thread and others that lump them all together. Its pretty clear that many people don't know what the expected behavior is.

Fair point. I think the reason they're lumped together is because the Model 3's reaction is so intense and sudden compared to other offerings, even in cases where some amount of braking is expected. This is still a bit of an issue (a lot of what the Model 3 brakes for is still over-reacting, though excusable if you come from the perspective of not betting on other drivers' behaviours), and perhaps even the cause of phantom braking's intensity (over-reaction to some unknown but brief trigger, which is likely misidentification of a risk).
 

DopeGhoti

Active Member
Aug 28, 2019
1,223
1,376
Phoenix, AZ
I find it interesting that reports of phantom braking for overpass shadows are so common; I drive under several overpasses daily and have never had this happen even once. It's possible the roads on my usual route are better-marked-up for the neural network, but even on other highways and surface roads with pedestrian bridges, I have yet to see my M3 suddenly decelerate without an immediately apparent factor as the cause (e, g, as others have noted: other cars turning into / across my lane of travel).
 

colettimj

Member
Feb 20, 2014
261
926
United States
1). When a car crosses in front of you at an intersection, even at a distance
2). When a car moves from your lane to an exit lane and is slow to completely leave your lane
3). A shadow from an overpass

These are the most common to me. If I think of more I will add to this.
1 & 2 I can anticipate and be ready to react. For 3, I've had it break for an overpass during my commute one day and then be fine another day with (seemingly) identical conditions.

I fear for the day when I'm manually accelerating to override "phantom braking" and AP is actually detecting a sudden stop of the car that's two cars ahead of me.
 
  • Like
Reactions: jdcollins5

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top