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Is Phantom Braking Still a Problem?

Well, as of mid -January I did an 8 hour round trip and used Autopilot with Auto-Steer for about 6 of those hours. I didn't have one phantom braking. Now mind you this was on a trip from Los Angeles to Las Vegas, and the return trip two days later.

The only time it braked, and it caught me off guard was a semi started drifting in my lane and I hadn't noticed it, but the AP had.

I used to have a point on my commute that would occasionally cause the phantom braking, but that one seems to have been fixed. It involved going through a small tunnel (overhead), and it got my attention the first time it happened. Now I don't even think about it, it goes right through it.

YMMV, but as I said, I use it with Auto-steer almost 90% of the time.
 
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jpfive

Member
Supporting Member
Oct 31, 2019
570
548
Pensacola, FL
Phantom braking problem in my car has been well addressed by the updates. It's a rare event now. From habit, though, I stay alert when I see a vehicle approaching from a side street on the right. My car seems to handle this pretty well now though. I will say that the braking function is more cautious than I would be. Traffic turning in front of me causes a quicker and stronger braking input than I would use if I was driving. Much improved, however.
 
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It is still an issue that happens in the same area on my daily commute, in the past 2 years it has significantly improved, only 4 times for me in the last 6 months, at this point only happens around the same 2-3 overpasses, it stills hesitates, also it very dependant on the time of day/shadow it sees. Hopefully, as they keep iterating it'll become a thing of the past, but for now it still good practice to be ready at least till you've driven in the same areas for a bit and see how it would react.
 
Today, yesterday, and the day before. All instances I was in the left lane of three on the interstate overtaking a vehicle that was in the middle lane. The car dropped 10 mph immediately (hard deceleration) before I hit the accelerator to power on past. In all cases the vehicle I am overtaking is in the center of its lane, not moving over or encroaching or crowding the line. I can’t figure out what the car is seeing that makes it brake.

It’s annoying enough that I turn everything off and finish my drive manually, happens about three times a week, once on each leg of my round trip about once weekly. It seems to happen more frequently now, not less.
 
I haven’t had a phantom braking event occur in quite a while. For me, it seems to have gotten a lot better with the latest 2020 and 2021 releases.

The big improvement I noticed was how it handles cars merging onto the highway from an on ramp while I’m in the right lane. In the first 2021 release (2021.4.3) I got, I noticed it didn’t slam on the brakes when a car was merging onto the highway. Big improvement for me but I rarely drive in the right lane so will need to see if it is consistently better.

In my 5 months of ownership, I’ve only had about 5-8 of these occur so it hasn’t been frequent for me.
 
It happened again this morning on my way to work, same circumstance. Semi in the middle lane of three, I was overtaking in the left lane. There was nobody behind me so I let the car do its thing to see what it would do, it hung back for 10 seconds at which point the semi signaled and moved into the right lane. About 5 seconds after it got into the right lane my car tentatively accelerated back up to speed.

Edit: The system is quirky, on my drive home from work my car will work its way over to the right hand lane on the interstate at exactly the same place every single time (just past an exit I don't take about 2/3 of the way home). If I'm in the left lane and the lane is clear ahead it still starts moving over and working its way through traffic so it can move into the right lane at that exact spot. No idea why. Otherwise it seems to prefer the middle lane, I assume because it has more evasive options if something happens, that makes sense.
 
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db93

Member
Mar 31, 2020
211
216
So Cal
It happened again this morning on my way to work, same circumstance. Semi in the middle lane of three, I was overtaking in the left lane. There was nobody behind me so I let the car do its thing to see what it would do, it hung back for 10 seconds at which point the semi signaled and moved into the right lane. About 5 seconds after it got into the right lane my car tentatively accelerated back up to speed.
Not really a "phantom brake" incident though
Cautious for sure :oops:
 
Yes, it still happens occasionally. Not really a phantom braking but more of a confused AI braking.
Both involve a 2 lane road and a stop sign on the side street.
case 1 is the side street connects to the main road at a 30 or 40 degree angle (or 140 to 150 angle depending on your reference point).
The stop sign is visible from the main road as I can read the letters. If TACC was tied into the Navigation, it would know that the stop sign was for the same road. However, during the day, the AI reacts to the sign and is unsure what to do so it tries to play it safe.

case 2 is a bit worse. Again 2 lane main road with another angled side road. However, you can only see the back side of the stop sign from one direction and again during the day the AI reacts to the shape (no red color and no letters).

case 2 just showed up recently after an update. Didn't happen before 2021.4.5. Now on 4.6 and still happens. Have an update *(4.11) waiting but have not installed it yet.
 
Not really a "phantom brake" incident though
Cautious for sure :oops:

Yeah, I get it, it's probably why it has such a low accident rate. But still, it brakes when the lane ahead is clear and the vehicles in the adjacent lane are centered in their lane, aren't moving around, aren't moving toward my lane, aren't crowding the line. I define that as phantom braking. If defined as braking when there are no other cars on the road, that has only happened a few times in the 8 months I have had the car.

"When I use a word, it means just what I choose it to mean—neither more nor less."
Humpty Dumpty, Lewis Carroll, Through the Looking Glass Ch 6
 
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It seems to be getting better in my experience. Happens less often. The getting dragged into the right side on ramp is also a problem, and equally dangerous.

THIS.

Over the weekend I was driving on a I88 (2 lane divided for the most part) from Davenport to Chicago and while cruising in the right lane and passing by every on ramp the car would shift right due to the widened lane. Would be nice if the car stayed anchored to the center line instead of the right lane marker in those situations because some on ramp shifts were abrupt enough that I had to take over to prevent a high speed zig-zag.
 

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