Model X

Sudden and erratic braking on autopilot



  • edited April 2019
    I think I’ve nailed it down as to what causes it. When there’s a car in a front quarter position, say at 1 o’clock, and the road turns opposite direction, in this case to the left, Tesla thinks its a cut in and brakes aggressively to allow car in even though its not changing lanes.
  • edited April 2019
    I think I’ve nailed it down as to what causes it. When there’s a car in a front quarter position, say at 1 o’clock, and the road turns opposite direction, in this case to the left, Tesla thinks its a cut in and brakes aggressively to allow car in even though its not changing lanes.
  • edited April 2019
    It's happened quite a few times to me, being I travel around Philadelphia quite a bit. It seems to mis-read cars around me and certainly is freaky, but I've learned that I won't/ can't trust this ModelX 100% of the time
  • bpbp
    edited May 2019
    During a 30 minute drive last night - had 4-5 times under NOAP with rapid braking while driving at highway speeds in heavy traffic.

    This appears to be caused by the new "Fleet Speed" feature added recently to NOAP/TACC that automatically reduces vehicle speed based on the speeds Tesla has recorded for other vehicles on the same section of road.

    This happens without any audible or visual warning, other than the speed decreasing on the speedometer and sometimes (but not always) reducing the TACC speed.

    Especially in areas of recent construction, relying on "Fleet Speed" is as bad a strategy as relying on the poor data in the onboard speed limit database.

    Plus it has the same flaws that Musk pointed out with the use of HD maps for AutoPilot - relying on past driving history doesn't necessarily reflect current driving conditions - and the correct strategy is to have the AP system do what a human driver would do - and use the current road conditions and signs to control operation of the vehicle.

    Tesla should either quickly fix the unnecessary braking (which is a safety hazard in heavy high speed traffic) OR, at least in the short term, add a setting to disable automatic speed adjustment.
  • edited May 2019
    Can’t fix what’s working.
  • edited June 2019
    Happened to me 2 times today with 30 seconds interval. Was going under bridges during the day light.
  • edited June 2019
    I've had the car brake for no clear reason any number of times, but lately it is much more severe. The other day it not only wanted to slow the car abruptly, it wouldn't give up. I kept pushing the accelerator to maintain speed, but for maybe half a mile every time I took my foot off the pedal it would slow down again. The cruise settings did not change in this case.

    In other cases I am on a highway and the set cruise speed would change from 60 to 35 MPH, then a tenth of a mile or so restore to the original setting!

    Teslas are possessed by the devil!
  • edited June 2019
    Overpasses are often interpreted as obstacles by the cruise control.
  • edited June 2019
    +1 for reporting this. Is there a way on how to report back these incidents so we can give more data points to Tesla to improve AP stability?

    Was on multilane high on auto-steer. Nothing in-front or surrounding but there were cars coming from the back. It very suddenly slowed down, almost like breaking. I had to push on accelerate to keep the car moving forward. Thankfully the car in the back was paying attention and he/she changed lane as well.

    Version 2019.15.103 a86d242
  • edited June 2019
    This happens/has happened for the past year, and is worse lately. We are on 2019.20.2 and get random ghost brakes at 60+ MPH when there aren't even any cars around. Just slams on the brakes and stays at 20mph until I disengage. Also veers towards dividers between highways with regularity.
  • edited June 2019
    Having the same problem. It's gotten so bad I'm afraid to use AP. Been submitting bug reports every time it happens.

    On 2019.16.2 73d3f3c
  • edited June 2019
    The Model X I am driving did the phantom emergency slam on the brakes today driving 70 mph. There was a bridge overpass in front . I drove 1,500 miles with no issues. Then it happened today after I updated to 20.1.2
  • edited June 2019
    Same on the P3D.

    Bridge overpass seems to be the culprit.
    Also, was on the far left lane & had a van to my right. Braking for no reason. Car in front of me was about 15-20 car lengths ahead.

    Tesla really needs to resolve this issue
  • edited June 2019
    I've had similar situations! It happened when I was on the PA turnpike in the pouring rain so I thought that may have made the car react erratically. But I've experienced it a few other times too
  • edited June 2019
    I'm experiencing this on the same spot (bay area, I-680 South bound..near mission blvd exit) every day.
    I'm on 2019.20.1.
    My colleague has 2019.15 on M3..and it does not have this problem.
    Stupid thing. Just slows down for no reason.
    I'm on the left most express lane and nothing in front of my car.
  • edited June 2019
    @teslarama - anything overhead when the braking happens on 680 (like FasTrack)??

    Had it happen on 880S, couple miles north of 238 today & 80W around Ashby Ave in Berkeley. Both cases, sign/overpass overhead.
  • edited June 2019
    @jjgunn..yes. There is FastTrack sign.
    There is one FastTrack sign under construction (the sign board is not fully setup...they just put the skeleton).
    May be it is not able to fully decode that (compared to other freeway signs and overpasses).
    I cross several overpasses on my commute from east bay to south problems any where else.
    I'll pay some more attention on Monday and see.
  • edited June 2019
    I've also suspected that this is more prevalent on overcast days. Then the sky is grayish white. While traveling on the highway on such a day, the braking was so annoying that I stopped using cruise control. I wish there was a way to disable the adaptive part until they fix it.
  • edited June 2019
    I thought this was only me. It started a few updates ago and continues with 2019.20.21 I was headed from AZ to LA a few months ago and turned on just the cruise part. It took the command and seconds later the car slammed the brakes on with no one in front or to the side of me. I tried it again the same thing. I called Tesla they said to reboot I did and did not make a difference. I have noticed the indicator for cruise and autosteer on the screen keep turning off and on a lot. These are on roads I used in the past several times with cruise and Autopilot but not anymore. At this point just fix my cruise one of the functions on most cars can't be used by our expensive machines is nuts. Fix this already!!!
  • edited June 2019
    This also happened to me, brand new X Raven, day two of driving, cruising on the 101frwy in California, 68mph, no vehicles in front of me for a thousand feet, no overpass, just me alone and wham, hard deceleration all the way down to 35mph on the freeway!!! OMG I thought what are you doing model x. Since seeing this happen a couple more times on the freeway I did happen to notice that one of the times the "indicated" speed limit on my front dash showed 35mph and I just waited and watched, did not interrupt the Tesla, and then noticed the "indicated" speed limit eventually go back up to 65mph. I suspect that when an adjacent slower road is next to the freeway and the GPS signal may be a bit on the inaccurate side may then get confused and the Tesla may think it's on the side road for just a moment, before correcting its location and speed and return to the properly posted speed limit for the road I'm actually on. I'm just glad I didn't get rear-ended, I can only imagine the headache that would of been for Tesla.
  • edited June 2019
    I have the above theory based off of my Radar detector that gives me false alerts of red light cameras while driving on the freeway just as I'm passing over or very close to another road that actually does have a red light camera at that location.
  • edited July 2019
    Was driving at 80 km and it suddenly stop had to takeover lucky to have my back. Reported to Tesla and the reply I got it has been more conscious I’m surprised that I can’t even use normal cruise control which is standard nowadays in most of the cars.
    I hope Tesla fix of this issue ASAP as this has happened twice to me and I’m just wondering what if somebody dashes me from the back :(
  • edited July 2019
    @deanzsyclone...GPS speed limit is not an issue in my case.
    It happens for me consistently on one particular spot (Bayarea, I-680 S bound, Mission blvd exit).
    Today..I checked...GPS speed limit stays at 65 MPH as normal.
    There is no car in front of overhead pass..nothing. Still slows down and then speeds up.
    My colleague will try model3 with the same SW version 20.4.2 tomorrow.
    Will see whether this is model X specific.
    I have the same SW version 20.4.2.
  • edited July 2019
    I mentioned in other threads

    SF (city) 101 Southbound -- right about hospital curve. Speed Limit slows to about 45 & car slows/brakes. Sucks
  • edited November -1
    Ok...we today tried model 3 with the same SW 20.4.2. Same problem in the same spot.
    The SW version 2019.15 did not have this issue.
    Still not able to figure out what the hell the it is seeing.
    Probably dead people. In my case also...slows to 45.
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