GMC 2012 Sierra - Manual (Page 204)

Black plate (4,1) GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
6-4 Lighting
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. For vehicles first sold in
Canada, the transmission must be
in the P (Park) position before the
automatic headlamp system can be
turned off.
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 or heavy overcast
weather. 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 are 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 comes on immediately.
Once the vehicle leaves the garage,
it takes approximately one minute
for the automatic headlamp system
to change to DRL 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.
To idle the vehicle with the
automatic headlamp system off,
turn the control to the off position.
The headlamps will also stay on
after you exit the vehicle. This
feature can be programmed using
the Driver Information Center (DIC).
See Vehicle Personalization (With
DIC Buttons) on page 5‑48.