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Major Phantom Braking Issues
- Thread starter LucLamma
- Start date
HankE-LA
Member
A couple days ago the wife's car coughed up several false warning messages. Following the advice on a forum was to basically reboot the car so all the computers would talk nicely to each other. After the reboot took it on a test drive to make sure everything was working. Cruise control was on with all the features. Suddenly the car phantom braked. I'm thinking something ahead tripped the logic circuit although there were no vehicles or pedestrians near me. Who knows.
Oh, the car? 2018 Accord with forward facing radar.
cmy4x4
Member
Updated software to 2023.32.1 last week and went on short 100 mile trip over the weekend. Multiple AGGRESSIVE phantom braking events during the trip. It seems to be getting worse than ever.
yikes. any chance you took 287 or 87 ? PB nightmare this summer driving back from Taos / NM to DFW.
i was hoping that they would address it eventually but if it seems to get worse... probably not taking the Tesla for roadtrips out there again
I see you’ve had a 2018 Tesla and now a 2020. Do you see any difference in number of phantom braking events? I’m trying to determine if the older US sensors in the 2019 are worth keeping the car a bit longer. I seldom have phantom braking, and really want to keep it that way.
sleepydoc
Well-Known Member
The US sensors are only used for short range detection (i.e. parking, blind spot detection.) The longer range detection needed for TACC and FSD is done via radar and vision.
radar was software deleted from HW 2.5 cars over a year ago.... "vision only" baby!
I have a 2019 M3 and phantom braking seems quite less (at least last 1 or 2 years). I am yet to upgrade to 2023/24 Tesla so can add on if I see PB with new one. This has prevented me from upgrading a year earlier. So I completely understand where you’re coming from. I’ll be keeping my fingers crossed with new one soon
My 2020 MY on FSD v11.4.7.3 has very rare phantom braking, except for two places i travel often - one is near an overpass over part of the road that sweeps downhill, I’m sure the car thinks the overpass is in the road; the other are a couple of overhead road signs on steel lattice-like supports - no idea what it thinks those are. Otherwise, phantom braking out of the blue is pretty rare, IMO.
stopcrazypp
Well-Known Member
The phantom braking I have experienced (I am on 2022.44.25.3 so no more radar) are almost exclusively when travelling past a set point in roads I frequently travel. The car would set a lower set speed, as if it was responding to a mapped check point, similar to how there are checkpoints ahead of curves (something the manual mentions), except it's a straight road with no reason to slow down. It is typically a junction where it does this, so very likely some mapping issue.
Not that hard to override with accelerator, but annoying.
Not that hard to override with accelerator, but annoying.
ElectricAnt54
Active Member
A year later, the above is still my experience.
In a few weeks I’m driving from Los Angeles to the northern edge of California. I plan on using autopilot + autosteer a lot.I don't see/experience any difference in phantom braking from my 2018 to 2022 to 2023 Tesla's. All had FSD so AP may be different. The 2018 had radar but was disabled around 2020 IIRC so all use cameras only for driving. The 2022/2023 do some strange slowdowns at times passing 18 wheelers. I would call them phantom braking but they are partial slowdowns. But, I love the way the latest FSD highway stack moves slightly left or right vs holding the center lane if a truck approaches my lane from either side.
The USS difference is remarkable but has nothing to do with anything other than parking and summons. The 2018 and 2022 with HW3 and USS, were/are better at distances and feedback vs the HW4 2023 that doesn't have USS. I have little confidence the Vision Only system will be as good as USS. But again, none of this relates to phantom braking.
This is a Tesla forum, we only complain about Tesla here, as they are the only ones with this problem. How dare you show other mfgs with the same issues.
Identical to all of my phantom experiences in the '21 MYLR. I don't get any of this in either of my '15 MS or '17 MX - they are smooth like butter.
I work in aerospace (real space, not planes), and some of my systems colleagues believe it's a cellular or satellite/GPS issue because the cars do exactly what you describe - when a braking event happens, the cruise control setting drops to some slower speed, as if the car thinks that's the speed in that general area, based on GPS mapping. This summer, we took the MY across Kansas, Missouri, Illinois and into KY. We only had phantom braking between eastern Colorado and around Salina KS. There were NO events from Salina to KY, nor were there from KY back to Salina. Then, from Salina to eastern CO, they started again, and coincided several times with my kids losing LTE on their tablets. It happened in either enhanced autopilot/FSD or standard adaptive cruise control.
My colleague believes it's a hardware issue with the GPS and/or cellular PCBAs/receivers that Tesla doesn't want to have to replace because there are too many out there, and to to them it's just a customer "inconvenience" (actually, Elon, it's a safety risk when you're driving 75 on an interstate passing a big rig, and then your car decides to adjust its speed to 50 mph right after you merge back in front of said big rig!).
To be honest, and I'm not an attorney, but it would seem that a class action lawsuit is in order because Telsa now charges people thousands of dollars for "enhanced autopilot" and FSD beta, yet in what seems to be impacting mostly M3s and MYs, those folks simply cannot enjoy autopilot on highways due to this major flaw.
I took my M3LR with FSDb to the Big Bend area in Texas recently. Most of that region has no cell service. I had no phantom braking issues or set speed issues at all and the car performed as well with cell service as without.
sleepydoc
Well-Known Member
The term ‘Phantom Braking’ has come to encompass several different phenomena and I don’t think there’s one single cause.
False AEB (auto emergency braking) activations - alarm blares, tires come close to locking up and you’re thrown to the dashboard. Likely due to artifacts or processing errors with the AEB system. I may have had one of these since I bought my car 3 ½ years ago. This appears to be what the Audi owners are complaining about above. These are also potentially far more dangerous as you run the risk of being rear ended if anyone is behind you.
Phantom Slowing - the car slows anywhere from 5-50 MPH, sometimes even coming to a complete stop. The slowing may be fairly aggressive and enough to push you forward In your seat but is not to the level of the full AEB activation described above. These are much more common in my experience. I suspect there are also more reasons for them as well.
As you describe, some are very repeatable. These are likely due to bad map data, GPS issues, etc. As an example, there’s a road that was recently rebuilt near me. When heading east approaching a mild bend in the road the car always slows about 10 MPH. It doesn’t happen heading west (which is ironically the inside/tighter radius of the curve). It happens at all times of the day in all weather conditions. Why? Who knows but I have noticed that the map data deviates from the road slightly here.
There are other cases that appear to be completely random. When I used to use TACC more often I would get random slowdows of about 10MPH every 5-10 min for no clear reason. No one has been able to explain these. My guess is it’s processing error leading to artifacts but who knows. The apologists would say that ‘they weren’t that bad’ or that ‘every car has them’ to which I vehemently disagree. Every other car I’ve driven with adaptive cruise has never had this issue.
Interestingly, the non AEB phantom braking events are far fewer, approaching non-existent when using FSD.
Edit: another cause of ’phantom’ braking events is when you are using TACC and have a route programmed into the NAV system. If you are approaching a turn expected by the route planner the system will slow down for you. I’ve encountered this where I decide to take a different route and I can’t figure out why the car is slowing only to realize later it was because it expected to turn.
If your tablets also lost LTE that doesn't seem like a receiver issue.
My hypothesis: the autopilot downloads, on the fly, mapping information from the "cloud" for the intended route a few miles ahead. But if that is not available it falls back on some base map information---which could be wrong and is not curated or updated well (as that costs money).
Another, but different, kind of phantom braking is when the road is very straight but there are undulations in elevation or mirages, so the particular geography of the road can play a part. That road section is very long, flat and straight. The system does better as well when there are cars ahead it can follow behind, so also the density of traffic plays a role. Moderate density is best.
But that wouldn't show a change in max speed limit, just sudden braking. Speed limit change == bad maps, or it misread a sign by the road, like 55 mph (when towing)
I mostly operate in SoCal where there is heavy Tesla coverage and lots of traffic---other than spurious speed limit changes (like it sees a "55 mph construction zone") which is obviously inoperative and everyone goes through at full speed FSDbeta works great on highway (better than base AP/EAP). Bad mapping is a major contributor to bad performance.
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There is a point where US80 southeast of Dallas would cross a county line and the car slowed from 65 mph to 25 mph if you let it. It was very repeatable. It might still be for all I know. Obviously a mapping issue of some sort. There were no speed limit signs or anything unusual. Did it exactly at the county line.
But I have also had the car not slow down when passing a new speed limit sign if the sign was occluded by a semi truck. And, there's a state highway where the car refuses to respond to reduced speed limit signs even though they are standard signs with perfect visibility.
And, sometimes when you turn onto a rural highway with 55+ mph speed limit, the car will use a default 25 mph until it gets to the first speed limit sign, usually a quarter mile down the road.
So, on one hand, it looks like the car uses map data for speed limits. On the other, it looks like a speed limit sign is required. But again, sometimes it doesn't care. But sometimes it does.
The inconsistency is most curious.
I agree.
I had my network card gone bad and could not connect to cellular signal. The difference in road routes and handling was day and night compared to when it was/is working.
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