Problem with Blind Spot Assist
 

The blind spot monitor is supposed to display yellow in the triangle until the speed of 20 is reached. It did so in my new 2017 GLC 300 on the trip home from the dealership and for a few days afterwards last week. But now the yellow low speed caution indicator has stopped working.

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?

I dont have the yellow triangle on my coupe - only the red notification comes up over 20mph.

A friend of mine has a CLS and it does have a yellow triangle

My GLC does not have the yellow triangle below twenty miles an hour. I have had a c class loaner that did not have it either. The GLE loaner I had did have it. Mercedes may have made a change.

BlueRidge - Just posted below on tread "Short-term review of 2017 GLC300" Think I will stop at dealer tomorrow and see if we missed something. But I just checked the settings an everything seems to be turned on correctly....

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.

I just drove my wife's GLC with BSA plus and did the test. No yellow light just red. I do not think the GLC has yellow light. See picture

Thanks to everyone for checking on whether the yellow warning light was operative. Not sure why MB left it off for the GLC.

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Mine has red light only. Not sure of the importance of having a yellow indicator; does this mean that I have no warning until speed is above 20 mph? :confused:

Blind assist only work above 20mph.

I could see why they used to have the yellow light. At least there was some indication that the system wasn't watching out for you. Seems puzzling that they took it away.

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?

According to the Owner's Manual the blind Spot Assist only works at above 20 mph like dieseldoc had mentioned. The manual did say that intensity of the light would be dependent on the time of day (controlled by light sensor)

the yellow triangle they got rid off for 2016. i asked about it when i got the car. apparently people were all confused by them. at least that's what i was told.

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.

GLA 250 yellow blind spot flashers staying on
 

Funny timing, I just wrote back to a GLA poster on this forum... I think getting rid of the yellow is a great move! It was totally confusing to someone who doesn't own the car - I ran into it on loaners and was very confused but I googled it and figured it out. Most won't bother and will think it means something else. Now I wish they would address the 20 mph thing ... after all, when you are parallel parked on a street, wouldn't it be great to have that scanning behind you for that biker coming up on you? As a biker, I sure wish it did.

Has stopped for the time being, but expect it to returen.
 

DeanR,

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. :mad:
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)).

yellow warning lights on blind spot assist
 

Have a 2017 CLA 250 sports. Only 6K miles on it. For the first 6K miles, yellow warning lights in both side mirrors came on when started car and for about 10 seconds going down street. They never came on at stop lights or going down road slowly. NOW all of a sudden, they stay on while driving under 17 MPH and when I am at a stop light. I thought they were malfunctioning. Called dealership and they say they are suppose to stay on under 17PMG all the time? I NEVER RECALL this happening. IS THIS THE CORRECT WAY THEY ARE SUPPOSE TO OPERATE?

I have a 2019 GLC 300, at the time of delivery they told me the yellow light should be on at stops and low speeds (under 30km/h). and then at higher speeds when someone is in the blind spot, red triangle lights up. But in reality I haven't seen the yellow light turn on, it's either off or a red light turns on. Am I missing something here? The owner's manual also doesn't talk about the yellow triangle!

i have a 2017 and do not see a yellow triangle at low speeds, Owners manual indicates it is active around 20 mph and up. In the 2017 owners manual this is shown on page 193, bottom right of page

2018 GLC 300 here and I have written before that I like the yellow light idea (our model did away with it for only the red light). Why? Because when you are going slowly in traffic -- ie near 20 mph -- the yellow light tells you you're on your own; meaning blind side assist is not engaged. In models without the yellow light when you are driving near the 20 mph cutoff, you cannot be sure whether there is no one in your blind spot or whether the cutoff simply has not been reached and is not engaged. Without knowing exactly how fast you are going the warning loses some usefulness to me.

I think this is model specific. The Car2Go car sharing service uses CLAs and GLAs here in Denver. Whenever I drive those cars, I see the behavior described here where the yellow triangle appears on start-up. The BSM system on my GLC does not work in the same manner.

with the Older Models when the Amber Colored Triangle Start Flashing is when there is a problem with the Sensor Located within the Bumper..