2001 Cadillac DeVille Owner's Manual - Page 124

Light Sensor Exterior Lighting Battery Saver If the headlamp or manual parking lamp control has been left on, the exterior lamps will turn off approximately 10 minutes after the ignition is turned to OFF. This protects draining the battery in case you have accidentally left the headlamps or parking lamps on. If you need to purposely leave the lamps on for more than 10 minutes with the ignition in OFF or ACCESSORY, turn the manual control knob off and then back on. To delay the lamps from turning off, see "Twilight Sentinel" in the Index. If the headlamp switch is turned on after the ignition key is moved to either OFF or ACCESSORY, the lamps will not time out. The light sensor for the DRL and the Twilight Sentinel is located in the center of the front defogger grille. If you cover the sensor, it will read "dark" and the lamps or the HEADLAMPS SUGGESTED message will be on whenever the ignition is on. 2-54