2003 GMC Sonoma Owner's Manual - Page 141

Daytime Running Lamps 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 daytime running lamps are required on all vehicles first sold in Canada. The DRL system will make your headlamps come on at reduced brightness when the following conditions are met: The ignition is on, the exterior lamp control is in OFF, the sensor detects daytime light, an automatic transmission is not in PARK (P), and the parking brake is released. When the DRL are on, only your headlamps will be on. The taillamps, sidemarker and other lamps won't be on. The instrument panel won't be lit up either. When it begins to get dark, the headlamps will automatically switch from DRL to the regular headlamps. The DRL system on some vehicles may turn off temporarily while the turn signals are activated. To idle an automatic transmission vehicle with the DRL off, put the transmission in PARK (P). To idle a manual transmission vehicle with the DRL off, set the parking brake. The DRL will stay off until you shift out of PARK (P) or release the parking brake. The following does not apply to vehicles sold in Canada. When necessary, you may turn off the automatic headlamp system and the Daytime Running Lamps (DRL) feature by following the steps below: 1. Turn the ignition to RUN. 2. Press the DOME OVERRIDE button four times within six seconds. After the fourth press of the button, a chime will sound informing you that the system is off. The system will revert back to the automatic on mode when the ignition is turned to OFF and then to RUN again. 3. To return to the automatic mode, push the DOME OVERRIDE button four times within six seconds (a chime will sound), or turn the ignition to OFF and then to RUN again. As with any vehicle, you should turn on the regular headlamp system when you need it. 3-14