Automatic Headlamp System - GMC 2005 Sierra Denali Owner's Manual

Shifting the transmission into PARK (P) will allow you to
idle the vehicle with the DRL off. The DRL will stay
off until you release the parking brake or shift the
transmission out of PARK (P).

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 headlamp off delay,
which will keep the headlamps on for a short time after
the ignition is turned off. For more information see
DIC Vehicle Customization on page 3-54.
Your vehicle has 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.
If you start your vehicle in a dark garage, the automatic
headlamp system will come on immediately. Once
you leave the garage, it will take approximately
one minute for the automatic headlamp system to
change to DRL if it is bright enough outside. During that
delay, your instrument panel cluster may not be as
bright as usual. Make sure your instrument panel
brightness control is in the full bright position. See
Instrument Panel Brightness on page 3-16.
To idle your vehicle with the automatic headlamp
system off, turn the control to the off position.
You may be able to turn off your automatic headlamp
system. See Daytime Running Lamps (DRL) later in this
section for more information.
As with any vehicle, you should turn on the regular
headlamps if you need them.
3-15