Cruise control - Random braking and speed reductions... anyone else?

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#1
First off, I really wish Tesla would offer just ordinary cruise control so that I don't have to continually monitor my speed while cruising on the highway, because the "active" cruise is unusable in it's current form. It randomly changes it's setpoint while I'm cruising on the freeway, making my car suddenly decelerate for no reason. It's not only annoying, it's dangerous. Today on the way to work it just suddenly changed from a setpoint of 73 mph to 30 and began braking hard. This happened in broad daylight and good weather when there were no other cars for several hundred yards in front of me (not that it'd be OK for it to do this in any conditions). As a separate issue, it will frequently (like perhaps once or twice per mile) slam on the brakes while I am overtaking other vehicles in adjacent lanes, presumably because the software thinks the adjacent cars might be moving into my lane (they aren't).

As it stands, I really can't use cruise control at all without being seriously annoyed (and no doubt annoying the other cars around me), meaning my 2019 tesla has less automation than my 1989 honda accord had. I'm praying this is mostly due to my firmware version (2019.7.105) and the relative newness of HW3.
 

MelindaV

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#2
sounds like your area has google map issues with adjacent low speed roads being picked up from the freeway. watch what the "speed limit" at the upper right corner shows when it is slowing down. If it is not correct to the actual limit, send the correction to Google Maps.
 

Frully

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#3
The current iteration doesn't read speed signs - it responds to geographic data baked into the map. It's likely that map data was generated when there was a construction zone or the like on that highway and hasn't been updated.

Aside: this is why the self-driving future can't rely heavily on historical data and rather wants a reactionary vision-based AI. Out of date info causes problems.

Until they update AP/cruise to use the camera to read the signs, use the bug report feature to raise the concern about the map segment.
-Activate the voice prompt and say (in one sentence) "bug report: speed limit incorrect on xyz road" (optionally add "is 30mph instead of 65mph")

I've had several map segments in my area fixed this way.
 

MJJ

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#6
I've experienced this behavior, at the exact same place, day after day (older s/w versions) and now to a lesser degree (severity and frequency, but still extant). I've bought into the map error theory, but if the map has been fixed, there should be NO symptom, not just LESS symptom.

But as to your thread title, not to worry, it's definitely not random ;)
 

Technical48

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#7
This is exactly why I'm glad I didn't pay 5kUSD for EAP (or 2kUSD when it was on sale). There really needs to be an option to disable TACC until such time that it becomes less useless.
 
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#8
100% agree, I am very disappointed I can’t use TACC because it always hits the brakes. I use cruise control everywhere, now I don’t have it at all. FSD is a pipe dream if you can’t make cruise work.
 
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#10
73 is less than the average speed of traffic on this road.

Jeff Foxworthy once said: "If the speed limit on the highway is 55 mph, you're going 80, and everybody is passing you, you live in New England".

He nailed it.
 
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#11
TACC works perfectly for me. I use it all the time. It's not the car, it's the maps in your area.
Isn't that a bit like saying "it's not the phone, it's the software"... I'm not sure there is any real difference these days. To put it another way, none of my other cars have this problem despite the existence of these maps.

This leads me to my next idea... until such a time as Tesla is able to make these advanced features work universally and reliably, perhaps there should be a way to disable them. As such, the car will at least be prevented from having less capability than a 90's Toyota. The user can keep track of where it does and doesn't work and activate it appropriately.
 
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Olds442

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#12
i have the issue on a couple roads that have frontage roads, where it's reading the speed limit on the frontage when i'm in the fast lanes. other than that, no issues here.
and as silly as this may sound, we use summon all the time so i am glad i ponied up for it. nav on ap works fine as well but i'd probably be fine with basic ap and not miss nav on ap. sorry to hear people are having issues.
 

garsh

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#13
Isn't that a bit like saying "it's not the phone, it's the software"... I'm not sure there is any real difference these days.
Yep, especially given that we rely on Tesla to update map information.

I'd feel a lot better about our chances of seeing FSD soon if Tesla would concentrate on fixing these kind of long-standing Autopilot issues. Whether it's due to incorrect map data, or possibly Autopilot misinterpreting a change in road surface as some kind of barrier (I get slowdowns on the interstate when approaching a bridge with a concrete top coat when the rest of the roadway is darker asphalt), these sudden, unnecessary slowdowns are a huge pain to deal with.

The car will always slow down as I approach this bridge in particular (image taken from Google Streetview - construction is long done).

1559302784757-png.26408
 

sduck

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#14
Isn't that a bit like saying "it's not the phone, it's the software"... I'm not sure there is any real difference these days. To put it another way, none of my other cars have this problem despite the existence of these maps.

This leads me to my next idea... until such a time as Tesla is able to make these advanced features work universally and reliably, perhaps there should be a way to disable them. As such, the car will at least be prevented from having less capability than a 90's Toyota. The user can keep track of where it does and doesn't work and activate it appropriately.
Well, yes, of course. But I thought it would be appropriate to throw that in, as it seems some areas have better maps than others. I wonder how many areas are like yours with lots of problems - whether it's more or less the case than not. And of course I've experienced phantom braking for what must have been a map error - had a few in Texas last week. But around here, it's always caused by bridge shadows and surface changes, and the latter only rarely.
 

nonStopSwagger

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#16
Until they update AP/cruise to use the camera to read the signs, use the bug report feature to raise the concern about the map segment.
-Activate the voice prompt and say (in one sentence) "bug report: speed limit incorrect on xyz road" (optionally add "is 30mph instead of 65mph")

I've had several map segments in my area fixed this way.
Did tesla get back to you after you had the maps fixed using bug reports? The "bug report" feature does not send any data to tesla. It just saves it in a log in your car, which might get download and reviewed (its up to the service tech) when you go to a service center.

 

jsmay311

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#18
This happens to me too. (Discussed here: https://teslamotorsclub.com/tmc/threads/random-tacc-max-speed-decreases.127189/#post-3530170)

sounds like your area has google map issues with adjacent low speed roads being picked up from the freeway. watch what the "speed limit" at the upper right corner shows when it is slowing down. If it is not correct to the actual limit, send the correction to Google Maps.
When I looked down, the speed limit in the upper corner indicated 55, which is correct for this road.

It wasn't a speed limit issue in my case either.
 

Long Ranger

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#19
This happens to me too. (Discussed here: https://teslamotorsclub.com/tmc/threads/random-tacc-max-speed-decreases.127189/#post-3530170)






It wasn't a speed limit issue in my case either.
In your TMC post you say it happens at a freeway interchange. TACC can temporarily reduce your set speed at interchanges even if the speed limit doesn't change. From the manual:

When enabled while on a highway interchange or off-ramp, Traffic-Aware Cruise Control may reduce your set speed in 5 mph (5 km/h) increments – to as slow as 25 mph (40 km/h) – to better match the reported speeds of other Tesla vehicles that have driven at that specific location. To override this and continue cruising at your set speed, tap the accelerator pedal or touch the plus (+) or minus (-) button on the touchscreen. The new set speed is maintained for the duration of the interchange or off-ramp (unless you override it or cancel Traffic-Aware Cruise Control). After the interchange or off-ramp, the set speed may revert or change as necessary based on the new location. For example, if you merged onto a different highway, the set speed reverts back to the set speed that was in use before driving on the interchange.
 

Klaus-rf

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#20
I see it randomly also. This aftn I was at least 50 meters from a car that pulled out from a stop street into my lane on a curve. Then accelerated briskly so I was never closer than the 50 meters. Car panicked with a nose dive braking mode for a second or so. Then went back to the speed limit as if there was no issue at all.

Random and erratic.