2007 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 222

When it begins to get dark, the automatic headlamp system will switch from DRL to the headlamps. When you turn the headlamp switch off, the headlamps will go off. 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 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 detects 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 224. To idle your vehicle with the automatic headlamp system off, turn the control to the off position. Automatic Headlamp System When it is dark enough outside, the automatic headlamp system will turn on the headlamps at the normal brightness, along with the taillamps, sidemarker, parking lamps, and the instrument panel lights. The radio back lighting will also be dimly lit. To turn off the automatic headlamp system, turn the exterior lamps switch to the off position. Turning off the automatic headlamp system with the headlamp switch is not available for vehicles first sold in Canada. Your vehicle has a light sensor located on the top of the instrument panel in the defroster grille that regulates when the automatic headlamps turn on. Be sure it is not covered, or the headlamps will come on whenever the ignition is on. 222