TACC and Speed Limit Changes

  • Please post everything related to v9 (2018.39.x) into the version 9 MEGATHREAD. Please do your part to keep this site organized for everyone by looking around or doing a search BEFORE posting. Thanks

  • Winter is here and the forum is starting to get flooded with cold weather threads and posts. Please heed the suggested threads and posts before you post something related to cold weather. This is a great place to start: https://model3ownersclub.com/threads/teslas-in-cold-weather.5271
  • It's OK to discuss software issues here but please report bugs to Tesla directly at servicehelpna@teslamotors.com if you want things fixed.

C141medic

Active Member
Joined
Aug 31, 2017
Messages
38
Location
NJ
Tesla Owner
Model 3
Country
Country
#1
Has anyone experienced this?

Had this happen today (I’m on FW 39.7).
Only TACC enabled without auto steer. Traveling at 50MPH (with gps indicating 50 on the top right of the display). No one in front of me. Posted speed limit of the road drops to 35MPH (gps also picked up the change and reflected 35MPH on the right side of display) however; the TACC did not adjust and car remained at 50MPH until I had to brake to slow down to the posted speed limit.

Also when going around curves with only TACC enabled the car is not slowing down whatsoever as the manual indicates that that’s what should occur.
“Traffic-Aware Cruise Control also adjusts the speed as appropriate when entering and exiting curves.”
 

3V Pilot

Top-Contributor
Joined
Sep 15, 2017
Messages
1,191
Location
Oro Valley, AZ
Tesla Owner
Model 3
Country
Country
#2
Has anyone experienced this?

Had this happen today (I’m on FW 39.7).
Only TACC enabled without auto steer. Traveling at 50MPH (with gps indicating 50 on the top right of the display). No one in front of me. Posted speed limit of the road drops to 35MPH (gps also picked up the change and reflected 35MPH on the right side of display) however; the TACC did not adjust and car remained at 50MPH until I had to brake to slow down to the posted speed limit.

Also when going around curves with only TACC enabled the car is not slowing down whatsoever as the manual indicates that that’s what should occur.
“Traffic-Aware Cruise Control also adjusts the speed as appropriate when entering and exiting curves.”

If the road is marked as a highway, like a state route in some places, the speed limit is not restricted or auto adjusted. Look on a map and see how the road is labeled.

For the issue of slowing around a turn I'm not sure as I haven't attemtped that on V9 yet. It used to work just fine, I'll try it tomorrow.
 

C141medic

Active Member
Joined
Aug 31, 2017
Messages
38
Location
NJ
Tesla Owner
Model 3
Country
Country
#3
If the road is marked as a highway, like a state route in some places, the speed limit is not restricted or auto adjusted. Look on a map and see how the road is labeled.

For the issue of slowing around a turn I'm not sure as I haven't attemtped that on V9 yet. It used to work just fine, I'll try it tomorrow.
Interesting. I’ll check it out. Is there any way to enable this in the settings for TACC to auto adjust to the posted speed limit regardless of the type of road?
Regarding the issue with the curve, the posted speed limit was 45MPH on the stretch of road prior to the curve and the posted speed limit by the approach to the curve was 25MPH. TACC definitely did not slow down anywhere near the curve and began to enter the curve at 45MPH until I took over and started braking.
 

Bernard

Well-Known Member
M3OC Supporting Member
Joined
Aug 3, 2017
Messages
243
Location
Hawaii, HI
Tesla Owner
Model 3
Country
Country
#4
Has anyone experienced this?

Had this happen today (I’m on FW 39.7).
Only TACC enabled without auto steer. Traveling at 50MPH (with gps indicating 50 on the top right of the display). No one in front of me. Posted speed limit of the road drops to 35MPH (gps also picked up the change and reflected 35MPH on the right side of display) however; the TACC did not adjust and car remained at 50MPH until I had to brake to slow down to the posted speed limit.

Also when going around curves with only TACC enabled the car is not slowing down whatsoever as the manual indicates that that’s what should occur.
“Traffic-Aware Cruise Control also adjusts the speed as appropriate when entering and exiting curves.”
I don't get speed limits here on the Big Island (something to do with Tom-Tom, the GPS provider, I am told), so I cannot comment on the speed reduction.
But as for curves, I stopped counting on TACC to do anything about them long ago -- I have yet to see TACC slow down for *any* curve, so I simply disengage it on winding roads or use the wheel to reduce its set speed prior to a known slow-speed curve. I'll try with 39.7, as I tried in the past with each firmware, but am not optimistic. Of course, this could still be related to the GPS issue with speed limits -- GPS tracks the car very accurately, but something in the connection between GPS position and road position is not working around these parts.
 

3V Pilot

Top-Contributor
Joined
Sep 15, 2017
Messages
1,191
Location
Oro Valley, AZ
Tesla Owner
Model 3
Country
Country
#5
Interesting. I’ll check it out. Is there any way to enable this in the settings for TACC to auto adjust to the posted speed limit regardless of the type of road?
Regarding the issue with the curve, the posted speed limit was 45MPH on the stretch of road prior to the curve and the posted speed limit by the approach to the curve was 25MPH. TACC definitely did not slow down anywhere near the curve and began to enter the curve at 45MPH until I took over and started braking.
There is no setting for what you are looking for, only max speed settings for Autopilot. Currently the cameras do not read speed limit signs so being posted doesn't always mean it's in the database that the car is using. I use autopilot on my daily drive to work and it slows for a curve where the speed doesn't change at all. I'll give it a try using only TACC and see what happens. Maybe you could try using autosteer on that curve and see if the car slows at all. That would be interesting to know.
 

C141medic

Active Member
Joined
Aug 31, 2017
Messages
38
Location
NJ
Tesla Owner
Model 3
Country
Country
#6
There is no setting for what you are looking for, only max speed settings for Autopilot. Currently the cameras do not read speed limit signs so being posted doesn't always mean it's in the database that the car is using. I use autopilot on my daily drive to work and it slows for a curve where the speed doesn't change at all. I'll give it a try using only TACC and see what happens. Maybe you could try using autosteer on that curve and see if the car slows at all. That would be interesting to know.
I’ll give it a shot with autosteer and see what happens.
 

garsh

Dis Member
Moderator
M3OC Supporting Member
Joined
Apr 4, 2016
Messages
7,620
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#7
Interesting. I’ll check it out. Is there any way to enable this in the settings for TACC to auto adjust to the posted speed limit regardless of the type of road?
According to the owner's guide, page 63:
"Note: When you adjust the cruising speed based on the speed limit, the set speed does not change when the speed limit changes. You must move the gear lever fully down once then release to cruise at the new speed limit."
 

Sandy

One obsession to the next
M3OC Supporting Member
Joined
Jun 3, 2017
Messages
788
Location
Cobourg, Ontario
Tesla Owner
Model 3
Country
Country
#8
Probably common knowledge but today I figured out when in TACC and adjusting set speed with the right side wheel ‘spinning’ it up or down changes the speed by 5 kph (didn’t try in mph). Beats clicking it 5 times.
 

FRC

Active Member
Joined
Aug 3, 2018
Messages
149
Location
Athens, Ga
Tesla Owner
Model 3
Country
Country
#9
Probably common knowledge but today I figured out when in TACC and adjusting set speed with the right side wheel ‘spinning’ it up or down changes the speed by 5 kph (didn’t try in mph). Beats clicking it 5 times.
same for MPH...very handy.
 
Joined
Sep 10, 2018
Messages
13
Location
Atlanta, GA
Tesla Owner
Model 3
Country
Country
#10
According to the owner's guide, page 63:
"Note: When you adjust the cruising speed based on the speed limit, the set speed does not change when the speed limit changes. You must move the gear lever fully down once then release to cruise at the new speed limit."
I find touching the speed limit display (white rectangle in the left panel) easier than pressing down on the stalk a second time whenever the car switches to a higher/lower speed zone. This also auto-adjusts for your prespecified offset to the speed limit just as the cruise stalk does.

Unlikely to be a realistic concern in any perceivable future (read before your warranty expires), but should also help minimize wear and tear from repeatedly depressing the cruise stalk on every street while on TACC.
 

3V Pilot

Top-Contributor
Joined
Sep 15, 2017
Messages
1,191
Location
Oro Valley, AZ
Tesla Owner
Model 3
Country
Country
#11
Okay, so I've used TACC on V9 to go around a turn and did slow the car down prior to the turn. No posted speed limit change and it waits until the last second but it does slow down before the turn. I'd say the computer takes a corner faster than most people would but I personally prefer this to going too slow.

I've also noticed that if I take the same turn with Autopilot engaged it seems to slow down just a hair sooner. Still takes the corner about the same speed but it seems like it slows just a few feet sooner.
 
Joined
Jul 4, 2016
Messages
15
Location
Hendersonville TN
#12
Has anyone experienced this?

Had this happen today (I’m on FW 39.7).
Only TACC enabled without auto steer. Traveling at 50MPH (with gps indicating 50 on the top right of the display). No one in front of me. Posted speed limit of the road drops to 35MPH (gps also picked up the change and reflected 35MPH on the right side of display) however; the TACC did not adjust and car remained at 50MPH until I had to brake to slow down to the posted speed limit.

Also when going around curves with only TACC enabled the car is not slowing down whatsoever as the manual indicates that that’s what should occur.
“Traffic-Aware Cruise Control also adjusts the speed as appropriate when entering and exiting curves.”
Maybe things changed with V9.

If I am travelling at 70 and enter a 55 zone the car slows down to 64 automatically. Why 64? because I have the audible speed alert set to 9 miles over the posted speed limit. Try setting the audible chime for say 3 miles over and see if the TAC slows down for you then.
 

garsh

Dis Member
Moderator
M3OC Supporting Member
Joined
Apr 4, 2016
Messages
7,620
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#13
I cannot for the life of me figure out how TACC/Autopilot determine when to change the speed. I have my Autopilot limits set to relative and 0 mph, IIRC.

This morning, I'm driving on interstates. Speed limit starts off at 65 mph, then drops to 55 mph. Here's what happens:
  • I start off setting my speed to 75 mph (in the 65 zone)
  • Speed limit drops to 55. EAP keeps my speed at 75 mph.
  • Right after taking a split, EAP changes my speed to 70 mph. Speed limit is still 55. Why the change?
  • Several miles later, EAP tries to change my speed to 65 mph. Speed limit is still 55. Why????!?!?!?
 
Joined
Sep 10, 2018
Messages
13
Location
Atlanta, GA
Tesla Owner
Model 3
Country
Country
#14
Pretty big guess here, but do the real speed limit and the speed limit as seen by the car (per car display) match, when this happens?

I can relate to unexpected braking feeling unnerving while on AP. I’ve reported two such bug reports on specific roads where this has happened for me. At least it’s consistently wrong (happens all the time on the specific section of that road) so imagine fixable!
 

garsh

Dis Member
Moderator
M3OC Supporting Member
Joined
Apr 4, 2016
Messages
7,620
Location
Pittsburgh PA
Tesla Owner
Model 3
Country
Country
#15
Pretty big guess here, but do the real speed limit and the speed limit as seen by the car (per car display) match, when this happens?
Yes they do. Sorry, I had actually thought to check that and should have included that in my post above.
That's what's really strange. The car sees no change in the speed limit, yet decides to change speeds. It makes no sense to me.

And this was on an interstate - no sharp curves to worry about either.