Exterior Lamps; Automatic Headlamp System - GMC 2001 Sierra 1500 Pickup Owner's Manual

Exterior Lamps

Your parking lamp and headlamp switch is on the
driver's side of your instrument panel.
Turn the knob clockwise to the parking lamps symbol to
manually turn on the following:
D
Parking Lamps
D
Sidemarker Lamps
D
Taillamps
D
License Plate Lamps
D
Instrument Panel Lights
2-58
Turn the knob clockwise to the master lamps symbol to
turn on all the lamps listed as well as the headlamps.
Turn the knob all the way counterclockwise to turn off
your lamps and put the system in auto headlamp mode.

Automatic Headlamp System

When it is dark enough outside, your automatic
headlamp system will turn on your headlamps at the
normal brightness along with other lamps such as the
taillamps, sidemarker, parking lamps and the instrument
panel lights. The radio lights will also be dim.
Your vehicle is equipped with a light sensor located on
the top of the instrument panel in the defroster grille.
Be sure it is not covered, or the system will be on
whenever the ignition is on.
The system may also turn on your headlamps when
driving through a parking garage, heavy overcast
weather or a tunnel. This is normal.
There is a delay in the transition between the daytime
and nighttime operation of the Daytime Running
Lamps (DRL) and the automatic headlamp systems so
that driving under bridges or bright overhead street
lights does not affect the system. The DRL and
automatic headlamp system will only be affected when
the light sensor sees a change in lighting lasting longer
than the delay.