2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 256

Safety Belt Reminders Driver Safety Belt Reminder Light When the engine is started, a chime sounds for several seconds to remind a driver to fasten the safety belt, unless the driver safety belt is already buckled. The safety belt light flashes for several seconds, then comes on solid for several more. Passenger Safety Belt Reminder Light For vehicles equipped with the passenger safety belt reminder light, several seconds after the engine is started, a chime sounds for several seconds to remind the front passenger to buckle their safety belt. The passenger safety belt light, located on the overhead console, comes on and stays on for several seconds, flashes for several more seconds and then comes on solid for several more. This chime and light sequence is repeated if the passenger remains unbuckled and the vehicle is in motion. This chime and light sequence are repeated if the driver remains unbuckled and the vehicle is in motion. If the driver safety belt is already buckled, neither the chime nor the light comes on. If the passenger safety belt is buckled, neither the chime nor the light comes on. The front passenger safety belt warning light and chime may turn on if an object is put on the seat such as a briefcase, handbag, grocery bag, laptop or other electronic device. To turn off the warning light and or chime, remove the object from the seat or buckle the safety belt. 4-32