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Cruise control/sensor glitch?

jct_4628

Member
Jul 16, 2014
70
2
Wisconsin
Every time I approach this intersection my cruise slows down. Once I pass it the cruise goes back to normal. Thinking it must have something to do with sensors or GPS since it always happens in the same place. This only happens going south on this road, it does not happen going north. I have not had this happen at any other intersection. My wife has had it happen to her in the same spot as well so it doesn't seem to be driver specific. It doesn't bother me, but it is weird. Anyone have any ideas?

 
Last edited by a moderator:

fwgmills

Member
Jun 30, 2015
151
70
Roanoke, TX
I noticed two things. First, it looks like the intersection is a T-junction and the car only slows when you get to a place where either you could turn right or another vehicle could turn right into your lane. Second, it slows to the speed limit...which is quite a coincidence. That certainly is strange. Does it only happen in your car or (if you have two Teslas, yours and your wife's) does it happen in both your cars?
 

jct_4628

Member
Jul 16, 2014
70
2
Wisconsin
I noticed two things. First, it looks like the intersection is a T-junction and the car only slows when you get to a place where either you could turn right or another vehicle could turn right into your lane. Second, it slows to the speed limit...which is quite a coincidence. That certainly is strange. Does it only happen in your car or (if you have two Teslas, yours and your wife's) does it happen in both your cars?
I go by probably 20 T-junctions on the way to work and this is the only one this happens at. The speed limit is always shown with the new update, but it is something weird that it goes to the speed limit. We only have one Tesla.


Appears MS is not seeing the lanes as well (grey lines disappear from dashboard) and car may be slowing down to posted speed limit.

Same as first person, I go by probably 20 T-junctions on my way to work. I did not have autopilot engaged so I don't see how the lines would make a difference. I go by intersections on roads that don't even have lines on cruise and nothing happens.

Those are both good suggestions but I don't think it is either of those. With my limited diagnostic skills it seems I can rule out autopilot since it is not being used. I can rule out sensor issues because it only happens at this intersection, and the sensors didn't flash anyway. The only thing I can think of is it is some sort of GPS point that causes an issue?
 

brkaus

Well-Known Member
Jul 8, 2014
8,021
6,507
Austin, TX
If you try the navigation to go through that intersection, does the navigation system know about it? Or does it route you elsewhere. Nav uses different base maps than google map.
 

jct_4628

Member
Jul 16, 2014
70
2
Wisconsin
I have never had navigation active while passing this intersection. It is my daily commute so it is not really necessary. I'll try having it active next time I go through. Not sure if this will work but here is the GPS coordinates to the intersection. It is 47 and D. Google Maps
 

jct_4628

Member
Jul 16, 2014
70
2
Wisconsin
Tried today with autopilot engaged and it did the same thing. Next time I drive by I will try having a navigation route active and see if that does anything.
 

Discoducky

P100DL, 2021 M3, 4 CT reservations and counting
Supporting Member
Dec 25, 2011
3,698
6,108
My mountain
Every time I approach this intersection my cruise slows down. Once I pass it the cruise goes back to normal. Thinking it must have something to do with sensors or GPS since it always happens in the same place. This only happens going south on this road, it does not happen going north. I have not had this happen at any other intersection. My wife has had it happen to her in the same spot as well so it doesn't seem to be driver specific. It doesn't bother me, but it is weird. Anyone have any ideas?


I believe what you are seeing is curve speed adaptation. But this looks like a bug as there is no curve to slow down or 'adapt' the speed into.

I believe it is slowing down due to the fact that is loses the lanes. You can see this on the instrument cluster where the lanes disappear then the car slows. As Autopilot will slow for curves, it is most likely taking this into account.
Have you tried putting on Autopilot (autosteer)? At the start of the video you seem to have lanes so it should engage. Try engaging it at a slower speed so we can see how it transitions at a slower/safer speed.
 
Last edited by a moderator:

jct_4628

Member
Jul 16, 2014
70
2
Wisconsin
I believe what you are seeing is curve speed adaptation. But this looks like a bug as there is no curve to slow down or 'adapt' the speed into.

I believe it is slowing down due to the fact that is loses the lanes. You can see this on the instrument cluster where the lanes disappear then the car slows. As Autopilot will slow for curves, it is most likely taking this into account.
Have you tried putting on Autopilot (autosteer)? At the start of the video you seem to have lanes so it should engage. Try engaging it at a slower speed so we can see how it transitions at a slower/safer speed.

I tried autopilot yesterday, did the same thing. There are sharper corners on this route that do not slow down like this. There are probably 20 intersections on this route also and it does not happen on any of them either. Your idea is the most logical so far, but I still don't understand why it would only be at this intersection, and not any of the thousands of others we have driven with this car since we got it.
 

jct_4628

Member
Jul 16, 2014
70
2
Wisconsin
With the new software update this weekend it no longer glitches at this intersection! I don't know what the problem was, or what fixed it but seems to be working normal now!
 

jct_4628

Member
Jul 16, 2014
70
2
Wisconsin
Which update is this? We had a not dissimilar occurrence a couple of days ago; we are on 2.9.172.


I'm not sure...whatever the second update was this week. It is -15 degrees here so I really don't want to go out to the garage to look. I'll try to remember to look tomorrow when I go to work :)
 

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