Nissan LEAF 2023 Owners Manual
9.11.4. Another vehicle approaching from behind
Illustration 1: The side indicator light illuminates if a vehicle enters the detection zone from behind in an adjacent lane.
Illustration 2: If the driver activates the turn signal when another vehicle is in the detection zone, then the system chimes (twice) and the side indicator light flashes.
Illustration 3: If the I-BSI system is on and your vehicle approaches a lane marker while another vehicle is in the detection zone, the system chimes (three times) and the side indicator light flashes. Then the I-BSI system activates to help return the vehicle back to the centre of the driving lane.
The radar sensors may not detect vehicles which are approaching rapidly from behind.
If the driver activates the turn signal before a vehicle enters the detection zone, the side indicator light will flash but no chime will sound when the other vehicle is detected.