With the engine running, a press 
mutes 
the sound.
With the ignition off, a press turns the system on.
 Increase or decrease the volume 
using 
the thumbwheel on the left-hand side...
   
 
   Other information:
    With the engine running, a press 
mutes 
the sound.
With the ignition off, a press turns the system on.
 Adjustment of the volume.
Use the buttons either side of or below the touch 
screen for access to the menus, then press the 
virtual buttons in the touch screen...
   
   On/Off
	 To switch the system on, 
	press this 
	button to defrost the rear screen and, 
	depending on version, the door mirrors. The 
	indicator lamp in the button comes on.Defrosting switches off 
	automatically to prevent 
	an excessive consumption of current...