2007 GMC Yukon Owner's Manual - Page 201

Daytime Running Lamps (DRL) Daytime Running Lamps (DRL) can make it easier for others to see the front of your vehicle during the day. DRL can be helpful in many different driving conditions, but they can be especially helpful in the short periods after dawn and before sunset. Fully functional DRL are required on all vehicles first sold in Canada. The DRL system will come on when the following conditions are met: • The ignition is on Automatic Headlamp System When it is dark enough outside, your 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 system will come on whenever the ignition is on. The system may also turn on your 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. 201 • The exterior lamps control is in AUTO • The light sensor determines it is daytime When the DRL are on, only your DRL lamps will be on. The taillamps, sidemarker and other lamps will not be on. The instrument panel back lighting will not be on either. 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, and your DRL lamps will illuminate, provided it is not dark outside.