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Emergency Braking only gives chimes?

Discussion in 'Model X' started by SoCal Tsla, May 16, 2017.

  1. SoCal Tsla

    SoCal Tsla Member

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    I'm currently on v8.1 17.17.4, and the emergency braking feature never actually braked for me, it gave chimes at most, or didn't work at all... This is a bug right? I just made the mistake about auto lane change and don't want to make a similar mistake in my next video...
     
  2. MXWing

    MXWing Active Member

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  3. GlmnAlyAirCar

    GlmnAlyAirCar Member

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    Correct. AEB and FCW are two independent features.
     
  4. gr2020

    gr2020 Member

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    Did you hit something? As I understand it, AEB activates when a collision is inevitable. If you didn't hit anything, presumably it didn't need to activate...
     
    • Disagree x 1
  5. gearchruncher

    gearchruncher Member

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    You get FCW (chimes) earlier than AEB, and how early is based on the setting in the UI. The point of the chimes is to give you enough time to react and completely avoid the accident.

    AEB auto brakes for you at the point that the accident is unavoidable, and you will likely still hit the other vehicle, but at a highly reduced speed.

    Sounds like everything is working as intended.

    The only way to "test" AEB is to drive right at another car and literally don't brake. At all.
     
  6. idealsol

    idealsol Member

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    I got my 1st AEB braking event yesterday, TACC engaged, no AS
    We were on a surface street going about 40 and the braking was severe
    It seemed to react to some construction cones or??

    My wife, who doesn't trust the AP features to begin with was pretty vocal, like WTF
    She said why did it do that. In full fanboy mode I tried to explain, but when she said a car behind us could have easily hit us, I didn't have a comeback

    AEB still a work in progress based on my experience. This was much more severe than the occasional phantom braking I've experienced on the freeway
     
  7. gearchruncher

    gearchruncher Member

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    That is not AEB. That is just TACC slowing down for perceived obstacles.

    If you want to know what AEB would feel like, at 30 MPH just suddenly put your foot all the way to the floor on the brakes and keep it there until you are completely stopped. That's what severe braking feels like.
     
    • Like x 5
  8. chillaban

    chillaban Active Member

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    Hopefully you keep a routine eye on rear traffic as part of your awareness scan that's made more possible by TACC, not to mention the person behind you would be at fault for not maintaining distance and you would almost certainly be protected against such a collision.

    Three years ago I had a car totaled because I stopped for a red light, and an old 80's pickup truck behind me rammed into me at full speed. The first thing he did after coming out with a bloody nose was knock on my window and ask "WHY THE **** DID YOU STOP? NOBODY STOPS FOR THAT"… The responding officer gave him a bit of an attitude adjustment but still, there's a ridiculous slippery slope when it comes to managing drivers behind you.

    More recently, on my 1000 mile road trip, getting out of the city after work, I noticed the driver behind me, a Honda CRV Uber driver, was playing with his phone in stop and go traffic, barely looking up. I could see the car did not have camera and radar in the adaptive cruise control package, and strongly suspected he was distracted. I moved out of the lane to find a new tail, and literally 30 seconds later I see him slam on his brakes and tap someone's bumper.

    To protect yourself you should always be mindful of what kind of driver is behind you and whether or not they're in a position to stop, especially if you drive in metro areas with a lot of traffic.
     
    • Like x 4
  9. idealsol

    idealsol Member

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    I could be wrong, but the instrument panel had the red alert and I believe I heard a chime??
    The braking was MUCH more severe than any TACC slow down braking I've ever experienced. It was truly attention getting
     
  10. MP3Mike

    MP3Mike Active Member

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    Unless something has changed AEB on AP2 cars is limited to 28MPH and slower. So if you were going 40 MPH it wasn't AEB.
     
  11. MorrisonHiker

    MorrisonHiker S 90D 17.32.6ca28227

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    Sounds like it was probably FCW (forward collision warning) if you saw red and heard an alert.
     
  12. chillaban

    chillaban Active Member

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    Indeed, FCW also can coincide with strong TACC braking. AEB would show a separate status message at the bottom, though in the heat of the moment it's easy to miss that.
     
  13. idealsol

    idealsol Member

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    Yes, the heat of the moment makes it hard to remember exact details. What I can say for sure is the car brakes were applied very abruptly for no actual problem with a car close behind us. We were on a moderate bend in the road and I suspect it reacted to a car in a lane to the left of us
     
  14. Periokid

    Periokid Member

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    Mine also has never braked. I have gotten the warning but the brakes have never engaged. I had an Audi with this feature and the brakes would activate. If it designed to brake at the point of an accident, that is a pretty terrible design.
     
  15. travwill

    travwill Active Member

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    Tesla's AEB isn't like the Suburu commercials you see on TV (little disappointing in that regard) where the car will come to complete stop and save you. It will hopefully just reduce the amount of impact. The warning is handy for you to stop before it kicks in. Here are the key paragraphs out of manual on Auto Emergency Breaking.
    • Forward Collision Warning provides visual and audible warnings in situations where there is a high risk of a frontal collision (see Forward Collision Warning on page 96).

    • Automatic Emergency Braking automatically applies braking to reduce the impact of a frontal collision (see Automatic Emergency Braking on page 97).
      1. Warning: Automatic Emergency Braking is not designed to prevent a collision. At best, it can minimize the impact of a frontal collision by attempting to reduce your driving speed. Depending on Automatic Emergency Braking to avoid a collision can result in serious injury or death.
     
    • Informative x 2
  16. Lbkmxp100d

    Lbkmxp100d Member

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    If I remember correctly it does have a minimum speed of 7mph (7-28mph).
     
  17. vandacca

    vandacca ReActive Member

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    Does AEB work in conjunction with one's braking or does manually pressing the brake over-ride AEB?

    Here is just another data point, but I'm not sure if it provides any useful information since I don't think I can tell if AEB is working or if it's me.

    After a few weeks of ownership last summer, I was traveling down the highway and traffic came to an immediate halt. I pressed down on the brake with what I believed to be sufficient force to stop in time, but my X seemed to very aggressively brake and come to a stop well ahead before I needed to. I could see the sweat beads on the driver's forehead behind me. I think I nearly scared him to death, but luckily he too stopped in time.

    I was surprised how hard the braking was, and I attributed it to my lack of experience driving the X (only had it a few weeks) and my possibly pressing the brake pedal harder than I thought I was. After reading this thread, I'm now wondering if I had some assistance from AEB.

    Thoughts?
     
  18. SoCal Tsla

    SoCal Tsla Member

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    I don't think MX's brake is so soft that is going to make the difference, however depending on the description of the AEB provided by other friends it doesn't sound like AEB either (coz you still have plenty of space), so I wonder what it really is....
     
  19. gearchruncher

    gearchruncher Member

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  20. chillaban

    chillaban Active Member

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    Yes, they changed this in 8.0, but getting a forward collision warning will prime the hydraulics. If you even tap the brake pedal in response to a FCW, your car will take that to mean you agree with the emergency warning, and the car will brake hard until you attempt to accelerate or otherwise cancel the maneuver.

    It's supposed to buy you reaction time, because a lot of times accidents could have been avoided if the driver actually braked to the car's limits. People tend to prioritize braking gently over guaranteeing that they have enough stop distance. But if you're not expecting it, it could make a false FCW situation a lot worse. It takes a lot of discipline, but when you get a FCW, stop accelerating and look before reaching for the brakes.
     
    • Helpful x 1

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