Greeting
Took my wife's 2021 CX-5 to the dealer with our concerns about the BSM not working as I thought they should. After a test drive with the technician, I was told that the blind spot sensors are in the rear bumper, and they use a "Dopler Radar" system. Because of this setup the indicator will only light up when we are being passed either on the right or left and not light up when we are passing a vehicle unless for some reason the vehicle we are passing speeds up and hangs in the cone area of the radar. This does not make sense to me as I would think if a vehicle is in the blind spot area the indicator should light no mater who is passing who. I know on my daughters GMC Arcadia the indicator in the mirrors light up not matter what the situation is if there is a vehicle in the blind spot area. Any owners have similar concerns/issues?
thanks
Gary

 

On mine 2020, the indicator in the mirrors light up if there is a vehicle in the blind spot area, unless at standstill.

 

The blind spot operation on my Mazda works exactly the same way on my wife's Subaru - When cars approach you for the most part but it works well.

 

Mine seems to come on as the cars enter the blind spot (as it should) also if you try to change lanes after a pass and a car is still in the blind spot, it will beep to warn you. I think it works as it should. Same as in my other cars with BSM anyway.

 

All this falls under category of ADAS (Advanced Driver Assistance Systems) as defined by NHTSA

IIHS, most well known for its more stringent than NHTSA crash testing has a reasonable and understandable summary of different systems
https://www.iihs.org/topics/advanced-driver-assistance
Check out these PSA type articles from the University of Iowa
Of particular interest is the angled parking situation for RCTA, and the resolution of the radar, which may not detect pedestrians and motorcycles. My understanding is the industry is moving to higher resolution radar units due to changes in FCC bandwidth rules which phase out the use of certain bandwidths used in radar blind spot detection in 2022,
https://mycardoeswhat.org/deeper-lea...traffic-alert/
Rear Cross Traffic Alert is intimately linked with blindspot warning, since the rear corner radar units are used to detect rear cross traffic.
https://mycardoeswhat.org/deeper-lea...-spot-warning/

 

My 2020 seems to work fine.
It will even signal on a way street if I'm stopped in a parking spot and a vehicle is going by.

 

Does it light up whether you are passing the vehicle or just if a vehicle is approaching to pass you. Mine only lites up if I'm about to be passed and not when I'm passing a vehicle and cannot see it either in the side mirror or rear-view mirror. As the name indicates I would hope the indicator would lite anytime a vehicle is detected in the "blind spot" area.
regards
Gary

 

It's a "blind spot" warning system so it looks at cars that are in your "blind spots".
The sensor(s) for this system is in the rear of the vehicle.
There is no reason for it to warn you about the vehicle you are overtaking.
I'm not being a wiseass, but frankly if you can't see the vehicle you are overtaking/passing, you shouldn't be driving.
As always, none of these systems are foolproof.