Cruise Control Speed Randomly Changes
#1
MBWorld Fanatic!
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Cruise Control Speed Randomly Changes
So when I am on a straight shot road with a 70 Speed limit, I put it at 80. Maybe 4-5 min on cruise control, it decreases to 45MPH or some other random speed. I am thinking the GPS in the car is thinking it is on another road, maybe a local road and taking that speed limit. I was going 80 today and car went to 15MPH! The car braked so hard and I freaked out. I did see in the dash it said 15MPH but no way it is 15MPH on a highway.... any other issues?
#2
So when I am on a straight shot road with a 70 Speed limit, I put it at 80. Maybe 4-5 min on cruise control, it decreases to 45MPH or some other random speed. I am thinking the GPS in the car is thinking it is on another road, maybe a local road and taking that speed limit. I was going 80 today and car went to 15MPH! The car braked so hard and I freaked out. I did see in the dash it said 15MPH but no way it is 15MPH on a highway.... any other issues?
Clean your windshield where the sensors are at top and see if it improves tomorrow.
#3
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2019 C63CS
Assuming you have the driver assistance package, then the adaptive cruise control will by default automatically adopt the recognized speed limit. This can be turned off in the vehicle settings. Your speed limit sign recognition is picking up incorrect speed limits, perhaps from a sign on an adjacent road or there's something wrong with your camera or as mentioned above, dirt on the windshield blocking part of the camera. I have the automatic speed limit adoption turned off. I don't find it very useful here in the USA. It was helpful in Europe where speed limits change frequently and are enforced with speed cameras, but it occasionally picked up a speed limit sign it shouldn't have and then slowed down unexpectedly. It didn't happen that often, so having it turned on was worth it to avoid speeding tickets. I can still manually adopt the current speed limit by pressing Resume at any point.
#5
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Read the owner's manual. It's in there. There are various speed adaptation settings for cornering, speed limits etc. that you can turn on/off. It's all under the Assistance settings for DISTRONIC. The below is for MBUX. COMAND has similar settings.
#6
Junior Member
Indeed it is in the manual under Assistance\Traffic Sign Assist\Limit Adoption (which I've not turned off!). This is the menu on my 23 GLE for anyone else who may be interested.