Mazda CX-3 Owner's Manual page 256

When Driving
i-ACTIVSENSE
Always check the surrounding area visually before making an actual lane change:
The system is only designed to assist you in checking for vehicles at your rear when
making a lane change. Due to certain limitations with the operation of this system,
the Blind Spot Monitoring (BSM) warning indicator light, the warning sound and the
warning screen indicator display may not activate or they might be delayed even though
a vehicle is in an adjacent driving lane. Always make it your responsibility as a driver to
check the rear.
NOTE
The Blind Spot Monitoring (BSM) will operate when all of the following conditions
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are met:
The ignition is switched ON.
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The Blind Spot Monitoring (BSM) OFF indicator light in the instrument cluster is
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turned off.
The vehicle speed is about 30 km/h (19 mph) or faster.
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The Blind Spot Monitoring (BSM) will not operate under the following circumstances.
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The vehicle speed falls below about 25 km/h (15 mph) even though the Blind Spot
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Monitoring (BSM) OFF switch indicator light is turned off.
The shift lever (manual transaxle)/selector lever (automatic transaxle) is shifted to
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reverse (R) and the vehicle is reversing.
In the following cases, the Blind Spot Monitoring (BSM) OFF indicator light turns
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on and operation of the system is stopped. If the Blind Spot Monitoring (BSM) OFF
indicator light remains illuminated, have the vehicle inspected at an Authorised Mazda
Repairer as soon as possible.
Some problem with the system including the Blind Spot Monitoring (BSM) warning
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indicator lights is detected.
A large deviation in the installation position of a radar sensor (rear) on the vehicle
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has occurred.
There is a large accumulation of snow or ice on the rear bumper near a radar sensor
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(rear). Remove any snow, ice or mud on the rear bumper.
Driving on snow-covered roads for long periods.
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The temperature near the radar sensors (rear) becomes extremely hot due to driving
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for long periods on slopes during the summer.
The battery voltage has decreased.
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WARNING