Mazda mx5 Owner's Manual page 230

When Driving
i-ACTIVSENSE
NOTE
In the following cases, the activation of the Blind Spot Monitoring (BSM) warning
lights and the warning beep may not occur or they may be delayed.
A vehicle makes a lane change from a driving lane two lanes over to an adjacent
lane.
Driving on steep slopes.
Crossing the summit of a hill or mountain pass.
The turning radius is small (making a sharp turn, turning at intersections).
When there is a difference in the height between your driving lane and the adjacent
lane.
Directly after pressing the Blind Spot Monitoring (BSM) switch and the system
becomes operable.
If the road width is extremely narrow, vehicles two lanes over may be detected.
The detection area of the radar sensors (rear) is set according to the road width of
expressways.
The Blind Spot Monitoring (BSM) warning lights may turn on in reaction to stationary
objects on the road or the roadside such as guardrails, tunnels, sidewalls, and parked
vehicles.
Objects such as guardrails and concrete walls
running alongside the vehicle.
A Blind Spot Monitoring (BSM) warning light may fl ash or the warning beep may be
activated several times when making a turn at a city intersection.
Turn off the Blind Spot Monitoring (BSM) system while pulling a trailer or while an
accessory such as a bicycle carrier is installed to the rear of the vehicle. Otherwise, the
radar's radio waves will be blocked causing the system to not operate normally.
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The walls at the entrance and exits of tunnels,
turnouts.
Places where the width between guardrails or
walls on each side of the vehicle narrows.