2009 Chevrolet Suburban Owner's Manual - Page 204

Daytime Running Lamps (DRL) Daytime Running Lamps (DRL) can make it easier for others to see the front of your vehicle during the day. Fully functional daytime running lamps are required on all vehicles first sold in Canada. The DRL system will come on when the following conditions are met: 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 in the defroster grille that regulates when the automatic headlamps turn on. Do not cover the sensor or the headlamps will come on whenever the ignition is on. The system may also turn on the headlamps when driving through a parking garage, heavy overcast weather, or a tunnel. This is normal. The ignition is on. The exterior lamps control is in AUTO. The transmission is not in P (Park). The light sensor determines it is daytime. When the DRL are on, only the DRL lamps will be on. The taillamps, sidemarker, instrument panel lights, and other lamps will not be on. When it begins to get dark, the automatic headlamp system will switch from DRL to the headlamps. To turn off the DRL lamps, turn the exterior lamps control to the OFF position and then release. For vehicles first sold in Canada, the transmission must be in the P (Park) position, before the DRL lamps can be turned off. 3-16