The driver can activate the function by placing the POWER button to the ON position and by selecting:

If you press the Blind-Spot Safety button while the function is canceled the indicator on the button illuminates and the function activates. In this case, the function returns to the state before the vehicle was turned off.

When the function is initially turned on and when the vehicle is turned off then on again while the function is in activation, the warning light will illuminate for 3 seconds on the outer side view mirror.
If the vehicle is turned off then on again, the function maintains the last setting.