Problem with Blind Spot Assist
The rest of the blind spot monitor system is working fine (triangle red when a car is in blind spot and beeps when I put on turn signal with a car in the blind spot.)
I tried turning the blind spot system off and then back on using the menu in the dash screen, but that has not fixed the problem.
Any suggestions on how I can fix it without taking it back to the dealership or what the possible cause of the problem could be?



The rest of the blind spot monitor system is working fine (triangle red when a car is in blind spot and beeps when I put on turn signal with a car in the blind spot.)
I tried turning the blind spot system off and then back on using the menu in the dash screen, but that has not fixed the problem.
Any suggestions on how I can fix it without taking it back to the dealership or what the possible cause of the problem could be?
Read this tread while sitting waiting for my car but it was ready before I could respond.
So I leave the dealership and sure enough my 17 GLC with P3 doesn't light up yellow above or below 20 mph. Never noticed it before. I clearly remember my 2014E (traded) did have the yellow light.
I brought up the owner manuals for the 17 & 14 from the MB USA web site. The 14E clearly says its there and you can test by turning the key to position #2 the yellow & red will show up. I tested my 2017GLC in position #2 and only the red shows in the test.
I left the dealer and there was a 2017 GLA SUV loaner in front of me at the traffic light with cars on either side of it. I could clearly see the yellow light in the mirror(s) although the car was not moving.
Back to the MB web site and I looked at the 2016 GLA (2107 available) and sure enough it talks about yellow blind spot mirror lights.
They talk about overtaking a vehicle and the closing distance speed being less than 7 mph. This will turn on the lights. I have not tested this yet but I am thinking the yellow warning has been dropped from the current "blind spot assistant" for the GLC because, I am not seeing the yellow light with the ignition key test.
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Any idea why the system didn't work below 20? I can't imagine the cameras would care whether you are moving or not. maybe MB disables it by choice at slow speed?
i think the yellow triangles are a good thing. let you know that the system is currently not monitoring. without them, you could think that its clear.
the system uses sensors in the rear bumper, on the side, they look like the same sensor for the parktronic system. no idea why it doesn't work under 20mph. that has always puzzled me.
I’ve driven several times since the event a couple days ago, and the problem hasn’t recurred, but I fully expect it will. The yellow lights have always been a positive to me, a little reminder, but never had them keep blinking long after I had accelerated well beyond 20mph.
Yellow triangle flashing happened to me yesterday for the first time. It occurred every 20secs interval or so with the yellow flash blinking 3 to 4 times in equal frequency until i turned of the car.

I turned of the car for 2 mins then restarted, the triangle initiated with red light the changed to yellow solid as normal (Below 20mph warming light (low intensity)).









