2003 GMC Sonoma Owner's Manual - Page 140

Automatic Headlamp System When it is dark enough outside, your automatic headlamp system will turn on your headlamps at the normal brightness along with other lamps such as the taillamps, sidemarker, parking lamps and the instrument panel lights. The radio lights will also be dim. Your vehicle is equipped with a light sensor on the top of the instrument panel under the radio speaker grill. Be sure it is not covered or the system will be 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. The DRL and automatic headlamp system will only be affected when the light sensor sees a change in lighting lasting longer than the delay. To idle your vehicle with the automatic headlamp system off, set the parking brake while the ignition is off. Then start your vehicle. The automatic headlamp system will stay off until you release the parking brake. As with any vehicle, you should turn on the regular headlamps when you need them. You may be able to turn off your automatic headlamp system. See "Daytime Running Lamps (DRL)" later in this section for more information. I f 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 light 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 Control" under lnterior Lamps on page 3-15. Lamps On Reminder A reminder chime will sound when your headlamps or parking lamps are manually turned on, the driver's door is opened and your ignition is in OFF, LOCK or ACCESSORY. To turn the chime off, turn the control counterclockwise or turn the instrument panel brightness thumbwheel down to the fully dimmed position. In the automatic mode, the headlamps turn off once the ignition key is in OFF. 3-13