Car randomly changing set speed to phantom speed limits

[Astraea]

Hey guys, long time no post! So new and not very fun thing going on with the car tonight(hoping it's not an ongoing problem). Driving down a highway near my home, that I have driven hundreds of times, its blue cruise enabled and a flat 65mph speed limit for nearly 40 miles straight. Wellllll tonight the car wanted to do everything but what I had my cruise set to. The car would think it read a 20mph speed limit sign and start to auto adjust to it. I reset the cruise then a mile later now it thinks it saw a 40mph sign. This was the behavior every few miles for random speed limits until I got sick of it after the 4th or 5th time it did it. Driving back along the same highway in the opposite direction, again 65mph the whole way, and it was doing it again, in different places and no obvious reason as to why. There aren't really any extra signs on the highway that could look like speed limit signs. The weather while dark, was clear skies, no moisture on the roads, and not very busy highway in either direction. Aside from some dust and a few bugs on the front of the car and just some dust up on the windshield. All sensors are free and clear of any debris that would block them. Anyone else know what could be going on with car??? I'm stumped.

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[BMT1071]

Hey guys, long time no post! So new and not very fun thing going on with the car tonight(hoping it's not an ongoing problem). Driving down a highway near my home, that I have driven hundreds of times, its blue cruise enabled and a flat 65mph speed limit for nearly 40 miles straight. Wellllll tonight the car wanted to do everything but what I had my cruise set to. The car would think it read a 20mph speed limit sign and start to auto adjust to it. I reset the cruise then a mile later now it thinks it saw a 40mph sign. This was the behavior every few miles for random speed limits until I got sick of it after the 4th or 5th time it did it. Driving back along the same highway in the opposite direction, again 65mph the whole way, and it was doing it again, in different places and no obvious reason as to why. There aren't really any extra signs on the highway that could look like speed limit signs. The weather while dark, was clear skies, no moisture on the roads, and not very busy highway in either direction. Aside from some dust and a few bugs on the front of the car and just some dust up on the windshield. All sensors are free and clear of any debris that would block them. Anyone else know what could be going on with car??? I'm stumped.

Well, your first problem is that you're using speed sign recognition. ?? Seriously though, to each their own on that. Was your GPS location accurate to your physical location when this was happening?

 

[Astraea]

Well, your first problem is that you're using speed sign recognition. ?? Seriously though, to each their own on that. Was your GPS location accurate to your physical location when this was happening?

I've never had issue with the speed sign recognition before, maybe 1 or 2 occurances of a bad read in the past 2 and half years? But yeah my location was correct at all times during the trips.

 

[Ravensfan1996]

I turned off speed limit recognition for this reason, it can read signs wrong, or any sign that may look like a speed limit sign.

 

[Mach-Lee]

Hey guys, long time no post! So new and not very fun thing going on with the car tonight(hoping it's not an ongoing problem). Driving down a highway near my home, that I have driven hundreds of times, its blue cruise enabled and a flat 65mph speed limit for nearly 40 miles straight. Wellllll tonight the car wanted to do everything but what I had my cruise set to. The car would think it read a 20mph speed limit sign and start to auto adjust to it. I reset the cruise then a mile later now it thinks it saw a 40mph sign. This was the behavior every few miles for random speed limits until I got sick of it after the 4th or 5th time it did it. Driving back along the same highway in the opposite direction, again 65mph the whole way, and it was doing it again, in different places and no obvious reason as to why. There aren't really any extra signs on the highway that could look like speed limit signs. The weather while dark, was clear skies, no moisture on the roads, and not very busy highway in either direction. Aside from some dust and a few bugs on the front of the car and just some dust up on the windshield. All sensors are free and clear of any debris that would block them. Anyone else know what could be going on with car??? I'm stumped.

It sets the speed limits based on both signs it sees, and GPS map data. If there were no speed limit signs, then it's doing it off map data alone. Unfortunately the map data is often wrong in rural areas, which causes the car to speed up and slow down to the wrong speeds.

You can verify the speed limit data on the map here: https://mapcreator.here.com/?l=39.3447,-95.2935,5,normal#join

Zoom way in on your road, click the (60) button at the bottom, click on a road segment, and check the speed attributes in the side panel. Continue clicking on each road segment to see if the limit is correct or changes. You can submit a correction, but it's tedious and takes a year or two to get approved and updated in the vehicle.

 

[Astraea]

It sets the speed limits based on both signs it sees, and GPS map data. If there were no speed limit signs, then it's doing it off map data alone. Unfortunately the map data is often wrong in rural areas, which causes the car to speed up and slow down to the wrong speeds.

You can verify the speed limit data on the map here: https://mapcreator.here.com/?l=39.3447,-95.2935,5,normal#join

Zoom way in on your road, click the (60) button at the bottom, click on a road segment, and check the speed attributes in the side panel. Continue clicking on each road segment to see if the limit is correct or changes. You can submit a correction, but it's tedious and takes a year or two to get approved and updated in the vehicle.

I appreciate the reply, but I have traveled this highway hundreds of times without issue in the past and this is a new problem. This highway connects the capital of Pennsylvania to Lancaster PA, another good sized city. I regularly use blue cruise on the stretch of highway and have never had an issue with the car reading phantom speed limit signs. The in car navigation and at the time I was using Android Auto using Google maps, both showed me correct GPS location.

 

[RickMachE]

I appreciate the reply, but I have traveled this highway hundreds of times without issue in the past and this is a new problem. This highway connects the capital of Pennsylvania to Lancaster PA, another good sized city. I regularly use blue cruise on the stretch of highway and have never had an issue with the car reading phantom speed limit signs. The in car navigation and at the time I was using Android Auto using Google maps, both showed me correct GPS location.

You can debate it all day, but it's doing exactly what Mach-Lee stated.

I just did a 4,700 miles trip. In a National Park, with a posted 45mph speed limit, it dropped to 25mph multiple times. That's due to the database.

 

[Astraea]

You can debate it all day, but it's doing exactly what Mach-Lee stated.

I just did a 4,700 miles trip. In a National Park, with a posted 45mph speed limit, it dropped to 25mph multiple times. That's due to the database.

I'm not debating how the system works, I'm saying that for some reason last night on this stretch of highway it wasn't behaving the way it normally does. There is no database issue I for this stretch of highway. Traveling this highway is part of my daily drive and I have never experienced this problem before.

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