2011 Chevrolet Express 1500 Cargo Owner's Manual - Page 170

6-4 Lighting street lights does not affect the system. The DRL and automatic headlamp system is only affected when the light sensor sees 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 30 seconds for the automatic headlamp system to change to DRL if it is light 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 6‑6. Automatic Headlamp System When it is dark enough outside and the headlamp switch is in AUTO, the automatic headlamp system turns on the headlamps, along with the taillamps, sidemarker, parking lamps, roof marker 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. 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. Do not cover the sensor or the system will come on whenever the ignition is on. The system may also turn on the headlamps when driving through a parking garage or tunnel. 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