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Wrong speed limit while using Autosteer - Software 20.12 5

Wrong speed limit while using Autosteer - Software 20.12 5

Last week I was driving down the I5 freeway in San Diego using Autosteer. My Model S slowed from the posted speed limit of 65mph and the speed limit sign on the display showed 45mph. I wondered if perhaps I had passed a temporary 45mph speed-limit sign that I hadn't noticed. I took the car out of Autosteer mode and drove with the traffic.

Yesterday I drove down the same stretch of I5 using Autosteer and noticed the speed limit shown on the display changed from 65mph to 45mph but the car didn't slow down. I had NOT passed any speed limit signs when the change occurred.

Anyone else noticing this behavior?

EVRider | 5 juin 2018

AP1 or AP2? On a freeway, the car should not react to speed limit changes, that’s only supposed to happen on secondary roads, but that section of road might be mapped incorrectly in the GPS database.

AP1 can visually read street signs, but I don’t think AP2 can do that yet (it relies on GPS data).

geekydon | 5 juin 2018

AP2 on a 2018 100D.

reed_lewis | 5 juin 2018

As @EVRider says, the speed that the autopilot goes does not change on a highway. Did the number in the circle to the left of the speed change when the car slowed down? If not, then it was most likely a phantom braking issue where the car 'saw' something that caused it to slow down.

Also if you are no on a highway and the speed limit is lower, then it will pop up a message on the bottom of the smaller screen saying something about the speed limit being lower and lowering the speed of the car.

TranzNDance | 5 juin 2018

This happened to me once in February in AP 2.5 car in the carpool lane on a freeway. The speed limit in the car changed to 35 mph and the car slowed down accordingly. I had to drive manually. It happened just that one time on a path that I have taken many times before and after.

bp | 6 juin 2018

We have several limited access highways in the area that were under construction within the last 1-2 years and had stretches with 45 MPH speed limits.

Even though those highways are now 65 MPH, when running AutoSteer with AP2 in those areas, the software will quickly slow down the car when it hits the 45 MPH sections.

If you're closely monitoring AP (which you should be doing), you can recover by manually using the accelerator to maintain full highway speed until you get out of the falsely identified 45 MPH section.

But, if you're not watching closely, the car will rapidly decelerate, which may pose a safety challenge if the cars behind you are following too close and they don't respond quickly enough to your rapid braking to 50 MPH when all cars are likely going 70+ MPH...

This has been a bigger problem since Tesla changed providers of the speed limit data last summer - and hasn't gotten any better, as far as I can tell. Tesla needs to get this issue fixed, since this creates a safety problem (rapidly braking in the middle of high speed traffic).

geekydon | 6 juin 2018

The speed indicated on the display changed from 65 to 45mph and the car slowed. The speed indicated remained at 45mph until I exited the freeway several miles later. There has been no construction slowdowns along that section of I5 in recent memory.

SpaceGhost | 6 juin 2018

BTW: 45mph is the speed it uses on well traveled roads when it does not know the speed limit. i.e. it sets the speed limit to 45mph in some 30mph zones as well. Perhaps it is the average or median speed of all speed limits it has documented. In some cases it seems to help navigation, as some of these 30mph roads are better shortcuts. In older versions, it did not show any speed limit on this 30mph road, but it also avoided using it for navigation.

EVRider | 6 juin 2018

@SpaceGhost: I doubt the car uses 45mph when it doesn’t know the real speed limit; that would be a big safety issue. In my experience no speed limit appears when the car doesn’t know the actual speed limit.

Boonedocks | 6 juin 2018

AP1 camera will read and react to the actual speed limit signs, even those that’s are the digital dynamic lighted kind.

AP2 uses a database only and will not react to any listed speed limit sign UNLESS it just so happens to coincide with the map database. If you encounter an obvious error you can send a “bug report” from the car with the appropriate information to request that the database be updated. (Good luck with that).

Until or IF AP2 cameras are one day activated and actually read the speed limit signs that is your only recourse.

jgisana | 30 octobre 2018

Speed limits are so inaccurate in my area autopilot would be dangerous to use. It should really be looking at the speed signs for this to really be safe.

Boonedocks | 31 octobre 2018

I was nice and emailed a few times with details and submitted "bug report" at the exact location. Nothin has changed from that in 6 months. Now I have started submitting "bug report" daily at all the locations the gps speed limits are wrong. EAP NoA is not useful when a 2 mile side entrance exit ramp running parallel to the expressway is the same 70mph speed and the GPS database locks me in at 45mph. Have to disengage AP every time now including NoA now.

rick | 31 octobre 2018

I've had a similar problem where the speed limit is showing 35 but the number in the circle is showing 29. The only way I've been able to fix it is to disengage. I have the speed limit set to relative +/- 10mph. Not sure how to fix