NISSAN 2014 Altima Sedan - Owner's Manual - Manual (Page 312)

If the driver activates the turn signal, then the
Blind Spot indicator light flashes and a chime will
sound twice.
NOTE:
If the driver activates the turn signal before
a vehicle enters the detection zone, the
Blind Spot indicator light will flash but no
chime will sound when the other vehicle is
detected.
Overtaking other vehicles
The Blind Spot indicator light illuminates if you
overtake a vehicle and that vehicle stays in the
detection zone for approximately 3 seconds.
The camera unit may not detect slower moving
vehicles if they are passed quickly.
If the driver activates the turn signal while another
vehicle is in the detection zone, then the Blind
Spot indicator light flashes and a chime will
sound twice.
LSD2114 LSD2116 LSD2117
Starting and driving 5-23