Automatic Headlamp System
When the exterior lamp control is set to AUTO and it is dark enough outside, the headlamps come on automatically.

There is a light sensor located on top of the instrument panel. Do not cover the sensor. Otherwise the headlamps will come on when they are not needed.
The system may also turn on the headlamps when driving through a parking garage or tunnel.
When it is bright enough outside, the headlamps will turn off or may change to daytime running lamps (DRL).
The automatic headlamp system turns off when the exterior lamp control is turned to
or the ignition is off.
See also:
Cellular and GPS Antennas
Avoid placing items over or near the
antenna to prevent blocking cellular
and GPS signal reception. Cellular
reception is required for OnStar to
send remote signals to the vehicle. ...
Anti-theft Alarm System Messages
THEFT ATTEMPTED
This message displays if the vehicle
detects a tamper condition. ...
Trailer Towing (eAssist)
The vehicle is neither designed nor
intended to tow a trailer. ...
