Automatic Headlamp; System - GMC 2012 Sierra Denali Owner's Manual

6-4 Lighting
When the DRL system is on,
only the DRL lamps are on. The
taillamps, sidemarker, instrument
panel lights, and other lamps will not
be on.
When it begins to get dark, the
automatic headlamp system
switches from DRL to the
headlamps.
To turn off the DRL lamps, turn the
exterior lamps control to the OFF
position and then release. For
vehicles first sold in Canada, the
transmission must be in the P (Park)
position before the DRL lamps can
be turned off.

Automatic Headlamp

System

When it is dark enough outside, the
automatic headlamp system turns
on the headlamps at the normal
brightness, along with the taillamps,
sidemarker, parking lamps, and the
instrument panel lights. The radio
lights will also be dim.
To turn off the automatic headlamp
system, turn the exterior lamps
switch to the off position and then
release it.
The vehicle has a light sensor
located on the top of the instrument
panel which regulates when the
automatic headlamps turn on. Do
not cover the sensor, otherwise the
headlamps will come on whenever
the ignition is on.
The system may also turn on the
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 automatic
headlamp system so that driving
under bridges or bright overhead
street lights does not affect the
system. The automatic headlamp
system is only affected when the
light sensor detects a change in
lighting lasting longer than the
delay.
If the vehicle is started in a dark
garage, the automatic headlamp
system will come on immediately.
Once the vehicle leaves the garage,
it takes approximately one minute
for the automatic headlamp system
to change if it is bright enough
outside. During that delay, the
instrument panel cluster may not be
as bright as usual. Make sure the
instrument panel brightness control
is in the full bright position. See
Instrument Panel Illumination
Control on page 6 7.