GMC 2008 Envoy - Manual (Page 151)

Instrument Panel Brightness
Press the knob located
next to the exterior lamps
knob to extend it.
Turn the knob to adjust the instrument panel lights. Turn
the knob all the way up to turn on the interior lamps.
Press the knob back into its stored position when
you are not using it.
Dome Lamps
The dome lamps will come on when you open a door
unless the dome lamp override is pressed in.
Dome Lamp Override
The dome override button
is located below the
exterior lamps knob.
To turn the dome lamps off, press the button. The dome
lamps will remain off when a door is open. This will
override the illuminated entry feature unless you use the
Remote Keyless Entry (RKE) transmitter to unlock the
vehicle.
To return the lamps to automatic operation, press the
button again. The dome lamps come on when a door is
opened.
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