SONATA(YF) >2013 > G 2.4 GDI > Body Electrical System > Electro chromic Inside Rear View Mirror > Compass Mirror>Description and Operation  
Function
1.
Push the A button lower of the rear view mirror to turn on the function of the compass mirror so that displays a sign of a direction on the small board in the upper-right side of the mirror.
2.
Push the A button again to turn off its function.