FORD 2008 Explorer v.3 - Manual (Page 107)

Automatic dimming interior rear view mirror (if equipped)
Your vehicle may be equipped with an interior rear view mirror which
has an auto-dimming function. The electronic day/night mirror will
change from the normal (high reflective) state to the non-glare
(darkened) state when bright lights (glare) reach the mirror. When the
mirror detects bright light from behind the vehicle, it will automatically
adjust (darken) to minimize glare.
Without voice activated
Navigation System or SYNC
With voice activated Navigation
System or SYNC
The mirror will automatically return to the normal state whenever the
vehicle is placed in R (Reverse) to ensure a bright clear view when
backing up.
Do not block the sensors on the front and back of the interior
rear view mirror since this may impair proper mirror
performance.
Do not clean the housing or glass of any mirror with harsh
abrasives, fuel or other petroleum-based cleaning products.
EXTERIOR MIRRORS
Power side view mirrors
Do not adjust the mirror while the vehicle is in motion.
The ignition must be in the ACC or ON position to adjust the power side
view mirrors.
Driver Controls
107