dial with a light symbol
 

hello, can anyone enlighten me as to a dial that is to the right of the steering wheel, which is beside the fog light and lights switches. the one I'm interested in is a dial which if you move it down then your headlights go down and if you move it up, your headlights go up. what i also want to know is, does this have to be at a particular setting?

Should normally be set at zero which is “up”. If you put a big heavy load in the boot and rear seat passengers you may need to adjust the headlights down to avoid dazzling other drivers.

Virtually redundant on nivomat equipped cars which is all uk XC90

Or cars with HID/Xenon lights which self level

Don't you have a handbook?