Buick 2009 Lucerne - Manual (Page 165)

Rear Window Defogger
The rear window defogger uses a warming grid to
remove fog from the rear window.
< (Rear Window Defogger): Press to turn the rear
window defogger on or off. An indicator light below
the button comes on to show that the rear window
defogger is on. Be sure to clear as much snow from the
rear window as possible.
The rear window defogger only works when the ignition is
in ON/RUN. The rear window defogger stays on for about
20 minutes after the button is pressed if traveling at slow
speeds. At higher vehicle speeds, the rear defogger may
stay on continuously. If turned on again, the defogger
only runs for about 10 minutes before turning off.
The defogger can be turned off by pressing the button
again, by turning the ignition to ACC/ACCESSORY or
ON/RUN, or by turning off the engine.
If the vehicle has heated outside rearview mirrors, the
mirrors heat to help clear fog or frost from the surface
of the mirror when the rear window defogger is on.
See Outside Heated Mirrors on page 2-37 for more
information.
Notice: Do not use anything sharp on the inside
of the rear window. If you do, you could cut or
damage the warming grid, and the repairs would not
be covered by the vehicle warranty. Do not attach
a temporary vehicle license, tape, a decal or
anything similar to the defogger grid.
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