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Weird Speed Limit Display

jorobsand

Member
Nov 12, 2017
300
290
Charlotte, NC
Yesterday, I was driving my MS P100D AP2.5 back home from a weekend trip and I noticed the following weird icons for speed limit indications that I have never seen before..

IMG_7120.JPG


This first image was when the speed limit in the area was actually 35 MPH. Not only did the display show only 34, but it displayed it using a graphic I have never seen before. When the speed limit on the road changed to 45, the display changed to this...

IMG_8872.JPG


Still the same weird icon, but also showing a value of 43.

Anyone else seen behavior like this before? Not sure I can explain it. For what its worth, the drive started while I was on an indian reservation, so not sure if that caused the Tesla's GPS to think I was in another territory. But it still doesn't explain the weird values. I also did not see this behavior when I initially drove into the area. The behavior continued while I drove off of the reservation and since it was messing with my pre-set for AutoPilot, I did a scroll wheel reset and the normal icon for the speed limit returned upon reboot.

Any ideas on what was going on?
 
  • Informative
Reactions: croman

jorobsand

Member
Nov 12, 2017
300
290
Charlotte, NC
Yes, GPS was correct while this was happening. Surely the car didn't think that the reservation was international territory, right? Even if, it only happened when leaving, not when entering and continued to happen when I was back in US territory.
 

MorrisonHiker

S 100D 2021.4.18.2
Mar 8, 2015
9,840
9,209
Colorado
Yes, GPS was correct while this was happening. Surely the car didn't think that the reservation was international territory, right? Even if, it only happened when leaving, not when entering and continued to happen when I was back in US territory.

It could be they are coded as independent nations in the database so they show up as non-US speeds. Did things return to normal once you started a new trip outside the reservation?
 

jorobsand

Member
Nov 12, 2017
300
290
Charlotte, NC
I could understand them showing up differently, but the reservations themselves still use US-standard traffic signs. But that also doesn't explain the MPH differences (34 display vs 35 posted or 43 display vs 45 posted).

I did the scroll wheel reset when I was on the interstate so I could engage AutoPilot as the difference in display vs posted speed limit was messing with the automatic speed differential I have set up. That's when it returned to normal. I have been to the reservation before a couple months ago and didn't see this behavior.

I wonder if it is a bug related to updated firmware.
 

JohnnyG

Weee!
Jun 24, 2016
872
1,188
Columbus, OH
That symbol is the speed limit sign in most of Europe, Australia, Hong Kong, and most likely many others. Yes, very weird that it switched to that, even weirder that it showed the numbers which it did. The fact that the GPS was showing your position correctly even further boggles the mind...
 

ItsNotAboutTheMoney

Well-Known Member
Jul 12, 2012
10,631
7,799
Maine
Those odd numbers look like conversion of km/h limits.
70km/h / 1.609km/mi = 43.5053 mph
55km/h / 1.609km/mi = 34.183 mph

So, perhaps a weird bug that had it thinking you were in an International zone so it showed sensible speed limit signs*, combined with conversions between mph and km and back that led to it showing weird mph numbers.

Reminds me of the Canadians who for a while had a firmware problem where their cars showed the wrong speeds.

* I am a Person From (Far) Away :p.
 
Last edited:

jorobsand

Member
Nov 12, 2017
300
290
Charlotte, NC
Well next time I am in that area, I will make sure to let the Cherokee tribe know that it is now officially recognized by Tesla as a sovereign nation. I will also let them know that they are now free to adopt the metric system :).
 
  • Funny
Reactions: croman

ponzu

Member
Apr 19, 2018
289
96
Southern California
Those odd numbers look like conversion of km/h limits.
70km/h / 1.609km/mi = 43.5053 mph
55km/h / 1.609km/mi = 34.183 mph

So, perhaps a weird bug that had it thinking you were in an International zone so it showed sensible speed limit signs*, combined with conversions between mph and km and back that led to it showing weird mph numbers.
Where Tesla gets its speed limit data and why this data is so wildly inaccurate and incomplete is still very much open to speculation. You convinced me that the weird numbers are conversions for km/h to mph, but the most likely issue is not a "weird bug", but the quality of data once again.

Speed limits are recorded in various databases (TomTom, OSM, Waze, etc.) per road segment. They are recorded in two pieces: a numeric value and a unit. Most contributors/editors leave the unit alone as each locality has a default unit. So for the reservation that OP crossed either
- the default unit is set incorrectly in the database Tesla uses (for the moment presumed to be TomTom) and was not noticed/corrected by the speed limit data contributor, or
- speed data contributor knowingly or unknowingly set the unit to km/h

Tesla is off the hook in either scenario. They made a blunder, it seems, adopting the speed limit database they did, but after that, and until the data source is changed, it is technically not their issue.

The problem is that even when the bad data is detected, neither Tesla nor TomTom provides a working mechanism for correcting it. Even if TomTom accepts the error reports made on their web sites, Tesla is not updating this data on board of its cars in real time.
 
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Reactions: srredbeard

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