Buick LaCrosse Owner's Manual page 17

Turns the lamps on when any
door is opened.
Keeps the lamps on all
the time.
There are front and rear reading
lamps.
The front reading lamps are located
in the overhead console.
The rear reading lamps are located
in the headliner.
Press to turn each lamp
on or off.
For more information, see:
The exterior lamp control is located
on the instrument panel on the
outboard side of the steering wheel.
Turn the control to the following
.
positions:
Turns off the exterior lamps.
The knob returns to the AUTO
position after it is released. Turn to
off again to reactivate the
AUTO mode.
Automatically turns the
exterior lamps on and off,
depending on outside lighting.