Cruise and speed control

[sceh]

Curious that such a simple question is not clear via Tesla.
I have a model Y.
When driving I will get a red speed icon and and number in blue plus, sometimes, and this is pretty random, the same underneath in grey.
As I understand it, the lower one means the Traffic Aware Cruise control is available and if I select cruise control it will use the speed indicated underneath. Three questions:
How does it determine if TACC is available?
If it isn't and I select it what are the conditions?
The grey icon sometimes has a small headlamp icon or a raindrop icon attached to it; What does this mean?

thanks for pointers.

BTW, as an aside, after weeks of digging i find that GPS is used to determine the speed limit and *maybe* it swill be refined by road signs and GPS is very often wrong - like when it gave me 10 mph on a motorway...

 

[sceh]

When I say GPS, I mean it is either GPS or, more likely, it is reading the downloaded map. Road signs might be used but in my experience, almost never

 

[SkyDog]

When I say GPS, I mean it is either GPS or, more likely, it is reading the downloaded map. Road signs might be used but in my experience, almost never

I've noticed the opposite and it seems road signs are used more than map data. For example: I'm on a 35 mph road, come to an intersection and turn onto a 55 mph road. My Tesla thinks the speed limit is still 35 until it sees a 55 mph sign.

 

[sceh]

Weird !Thanks. Why can't we get a clear and definitive answer from Tesla,

 

[sceh]

There is a motorway near me which is normally 110KMPH. The general limit is 130. The car sets itself to 130 and miles later, even though it is legally 110, there is a sign for 110 and it changes to 110 but then misses the 90 sign three times in a row and then changes.
All this and many more examples lead me to think it uses the map but it is not at all clear. Does anyone know how we get this answered by Tesla. Not worth asking my garage who thinks that Tesla communicate with the car by satellite..

 

[Calliope]

It might depend on which roads (major v minor, highway v business/residential). I know for much of my regular route driving, my Tesla Y definitely reads signs, if they're visible. This spring, a speed change sign was mostly hidden by new tree growth, and the car didn't see it and kept the old speed, but when the roadside growth was trimmed so the sign was more visible, the car saw it every time. On the other hand, on a stretch of highway that had recently been increased to a speed limit of 110, it sill shows the typical (and previous) speed limit of 100 for that highway.

I have no idea what red and blue things your seeing on your screen -- it must be part of the FSD, which I don't have.

 

[Fourdoor]

I wish that Tesla didn't have the car limiting speed on certain roads. That "feature" should be limited to cars equipped with FSD. The car is not in control of what it going on, the driver is... so mistakes in the cars assumption about what the speed limit is should not affect how the car behaves when the driver knows better than the car knows. For example a rural highway between my small town and the nearest major city has a speed limit of 55 mph (88 kph), the car has incorrect map data that says the speed limit is 25 mph (40 kph). Rural highways don't have speed limit signs on sections that pass through farm fields, the last speed limit sign is as you leave town... 5 miles after the car sees that sign when leaving town it reverts to the (incorrect) map data. Because this is not a limited access highway, AP is limited to 5 mph (8 kph) higher than what it thinks the speed limit is... so on that section of road I can not use AP unless I am willing to either limit myself to 30 mph (48 kph) in a 55 mph (88 kph) zone where most people are doing 65 to 70 mph (105 to 113 kph), or (what I actually do) override the speed control with my right foot on the accelerator.

Later,

Keith