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cruise brakes automatically in traffic? is this normal?

Tesla model y 2021 LR (NO FSD) cruise breaks automatically in traffic

> i am on cruise <55 MPH and i noticed it breaks itself if there is a car in front of me (50% of the time i noticed it works with no Auto pilot turned on). Is this normal behavior?
> Also on Auto pilot, not every time but i noticed it set the speed limit automatically on some roads.
Example: If you have autopilot set to 55 and sets back to 45 when it detects 45 speed limit board, of course this feature works like one in 7 times or so, i dont remember exactly.
 

Impaler

'20 MY LR Black/Black, 20" induction w/FSD
Jul 5, 2020
309
162
USA
Tesla model y 2021 LR (NO FSD) cruise breaks automatically in traffic

> i am on cruise <55 MPH and i noticed it breaks itself if there is a car in front of me (50% of the time i noticed it works with no Auto pilot turned on). Is this normal behavior?
> Also on Auto pilot, not every time but i noticed it set the speed limit automatically on some roads.
Example: If you have autopilot set to 55 and sets back to 45 when it detects 45 speed limit board, of course this feature works like one in 7 times or so, i dont remember exactly.

There is a known "stealth braking" issue with Teslas. I know in my 2020 MY, I avoid using TACC/Autosteer on certain roads, because it will brake with no warning - and it's quite jarring. For instance, on a road with cars on the shoulder, it will do that sometimes, even though I'm nowhere near clipping any of the cars on the shoulder. In the DC area, it will also do that occasionally when getting near certain overpasses, even in express lanes. It's especially terrifying at 70 mph! I think it's gotten better recently, especially after driving with the 2021.4.3 update.
 
There is a known "stealth braking" issue with Teslas. I know in my 2020 MY, I avoid using TACC/Autosteer on certain roads, because it will brake with no warning - and it's quite jarring. For instance, on a road with cars on the shoulder, it will do that sometimes, even though I'm nowhere near clipping any of the cars on the shoulder. In the DC area, it will also do that occasionally when getting near certain overpasses, even in express lanes. It's especially terrifying at 70 mph! I think it's gotten better recently, especially after driving with the 2021.4.3 update.
 
Tesla model y 2021 LR (NO FSD) cruise breaks automatically in traffic

> i am on cruise <55 MPH and i noticed it breaks itself if there is a car in front of me (50% of the time i noticed it works with no Auto pilot turned on). Is this normal behavior?
> Also on Auto pilot, not every time but i noticed it set the speed limit automatically on some roads.
Example: If you have autopilot set to 55 and sets back to 45 when it detects 45 speed limit board, of course this feature works like one in 7 times or so, i dont remember exactly.

There are three possible basic modes:
1. Manual - You drive the car. It may (is supposed to) emergency brake but that is not something you would normally encounter in normal driving.

2. Traffic Aware Cruise Control (TACC) - Enabled with one press down on the shifter stalk. The car will maintain a safe (selectable) distance to the car in front of you, but won't exceed the Max Speed setting. It will brake as necessary, except when it rarely doesn't. This is a simplistic version of FSD that does make mistakes. In this mode you still have to steer the car. I'm hoping this is the braking you are seeing with no Auotpilot.

3. TACC + Autosteer - This is what I would consider "Autopilot". Enabled with two quick presses of the shifter stalk, even if you're already in TACC. TACC is active, even if you start this mode while driving manually, so the car will brake automatically. It also steers to stay within your lone. Again, these are simplistic implementations that will make mistakes, so be ready to take over at any time.

With Autosteer active, the maximum speed allowed is 5 MPH over the speed limit. Autopilot will enforce that automatically if the speed limit is slower than your current Max Speed setting. If that does occur, it will also increase the Max Speed if the speed limit is raised later on. However, it will not exceed your originally set Max Speed. So if you are at your Max Speed and the speed limit increases, Autopilot will not automatically increase the Max Speed to match. If you are driving manually or using TACC only, Autopilot will not adjust the Max Speed at all in response to speed limit signs. It will adjust speed in corners and freeway exits and a few other times when necessary.
 

Impaler

'20 MY LR Black/Black, 20" induction w/FSD
Jul 5, 2020
309
162
USA
. TACC + Autosteer - This is what I would consider "Autopilot".

With Autosteer active, the maximum speed allowed is 5 MPH over the speed limit.

Great description above! Technically, "Autopilot" is a family of capabilities, which included with all new Teslas, includes both TACC and Autosteer, and for some, the optional $10K FSD features. So really, whether you're using TACC alone or Autosteer (which essentially is TACC plus lane control), you're using Autopilot.

Using Autosteer, the 5 MPH over the limit, in my experience, applies when going less than 50 MPH. Over 50 MPH, I'm able to set it to whatever speed I want, up to the max speed limit set in the settings (I haven't enabled it). I can demonstrate, on a 55 MPH road near my house right now, that enabling Autosteer the car will let me set a cruise speed of, say, 75 MPH. It won't stop me.
 
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...and the fourth option is "Navigate with Autosteer" which only works on freeways. It will change lane automatically if it comes up on slower traffic, move right to avoid driving in the left lane, and take the appropriate exit before handing back control to the driver.
 
yes, and if you go over that limit while trying to pass someone, you get the big RED steering wheel and you go into the penalty box and are banished from autosteer till you stop again! UGH. LOL
Is that true even where the speed limit is 85? I mean, I generally consider all other drivers maniacs*, but surely exceeding the limit by 10 mph for a moment to pass someone seems reasonable?

*Per George Carlin, "Anyone who drives faster than you is a maniac; anyone who drives slower than you is a moron."
 
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