When it is dark enough outside and the exterior lamp control is in the automatic position, the headlamps come on automatically. See Exterior Lamp Controls.

The vehicle has a light sensor on top of the instrument panel. Make sure it is not covered, or the headlamps will be on when they are not needed.
The system may also turn on the headlamps when driving through a parking garage or tunnel.
Lights On with Wipers
If the windshield wipers are activated in daylight with the engine on, and the
exterior lamp control is in AUTO, the headlamps, parking lamps, and other exterior
lamps come on. The transition time for the lamps coming on varies based on wiper
speed. When the wipers are not operating, these lamps turn off. Move the exterior
lamp control to
or
to disable this feature.
Daytime Running Lamps (DRL)
Hazard Warning FlashersInstrument Panel Outer Air Outlet Replacement - Left Side
Instrument Panel Outer Air Outlet Replacement - Left Side
Callout
Component Name
Preliminary Procedure
Remove the left instrument panel upper trim panel. Refer to Instrument
Panel Upper Trim Panel Replacement - Left Side.
...
Throttle Body Heater Outlet Pipe Replacement (LUW)
Throttle Body Heater Outlet Pipe Replacement
Callout
Component Name
Preliminary Procedure
Drain the cooling system. Refer to Cooling System
Draining and Filling.
1
Engine Coolant Air Bleed Hose
...
Front Differential Carrier Installation (6T40/45/50)
Front Differential Carrier Installation
Callout
Component Name
1
Final Drive Sun Gear
2
Differential Carrier Assembly
3
Front Differential Carrier Bearing Asembly
...