Mazda 3 Owner's Manual page 235

When Driving
Blind Spot Monitoring (BSM) System
NOTE
The Blind Spot Monitoring (BSM) does not operate when the vehicle speed is lower than
about 10 km/h (6.2 mph).
The detection area of the Blind Spot Monitoring (BSM) has been determined based on
the lane width of general freeways. Therefore on a road with a narrower lane width, the
system may detect vehicles on a lane next to the adjacent lane and operate the warning
light/beep. On a road with wider lane width, the system may not detect vehicles on the
adjacent lane and may not operate the warning light/beep.
Under the following conditions, the system may be unable to detect vehicles, or detection
may be delayed.
The vehicle accelerates from a standing-start with a vehicle alongside.
A vehicle moves from a lane two lanes over to the adjacent lane.
The difference in vehicle speed between your vehicle and another vehicle is larger
when passing or being passed, and the vehicle passes the detection area within a short
period of time.
On a steep incline, or when there is a difference in height between lanes.
Immediately after the system has been activated by pressing the Blind Spot Monitoring
(BSM) OFF switch again after it has been turned off (Blind Spot Monitoring (BSM)
OFF indicator light in instrument cluster illuminates) by pressing the switch.
(Automatic transaxle vehicles)
The shift lever is shifted to the R position, or directly after being shifted from the R
position.
The system may not operate normally when towing a trailer. Turn off the system by
operating the Blind Spot Monitoring (BSM) OFF switch when towing a trailer.
The system switches to the Rear Cross Traffi c Alert function when the shift lever (Manual
transaxle) or the selector lever (Automatic transaxle) is shifted to the R position.
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