2015 Cadillac XTS Owner Manual - Page 186

Lighting 6-9 Battery Power Protection The battery saver feature is designed to protect the vehicle's battery. If some interior lamps are left on and the ignition is turned off, the battery rundown protection system automatically turns the lamp off after some time. Exterior Lighting Battery Saver The exterior lamps turn off about 10 minutes after the ignition is turned off, if the parking lamps or headlamps have been manually left on. This protects against draining the battery. To restart the 10-minute timer, turn the exterior lamp control to the off position and then back to the parking lamp or headlamp position. To keep the lamps on for more than 10 minutes, the ignition must be in the ACC/ACCESSORY or ON/RUN position.