2005 GMC Envoy Owner's Manual - Page 170

Safety Belt Reminder Light When the key is turned to RUN or START, a chime will be provided for several seconds to remind people to buckle their safety belts. The driver safety belt light will also be provided and stay on for several seconds, then it will flash for several more. You should buckle your seat belt. This chime and light will be repeated if the driver remains unbuckled and the vehicle is in motion. Passenger Safety Belt Reminder Light Several seconds after the key is turned to RUN or START, a chime will be provided for several seconds to remind the front passenger to buckle their safety belt. This would only occur if the passenger airbag is enabled. See Passenger Sensing System on page 1-62 for more information. The passenger safety belt light will also be provided and stay on for several seconds, then it will flash for several more. You should have the passenger buckle their safety belt. This chime and light will be repeated if the passenger remains unbuckled and the vehicle is in motion. If the driver's belt is buckled, neither the chime nor the light will be provided. If the passenger's safety belt is buckled, neither the chime nor the light will be provided. 3-34