Blind-Spot Monitoring (BSM)
Blind-spot monitoring (BSM) watches areas beside and slightly behind the vehicle that can be difficult to see in the mirrors. Rear corner radar sensors are common, although the sensor arrangement varies.
What it does
When another vehicle is detected in a monitored zone, BSM usually illuminates an indicator in or near the corresponding side mirror. If the driver signals toward that side, the system may add a stronger audible or visual warning. Basic BSM warns; a separate blind-spot intervention feature may steer or brake.
The monitored area, supported targets, and activation speeds differ. Motorcycles, rapidly approaching vehicles, stationary objects, trailers, barriers, bad weather, dirt, and sensor damage can affect detection. The system does not replace mirror checks or looking over the shoulder before changing lanes.
For sensor placement, warning logic, and intervention variants, see Blind-Spot Monitoring.