2004 GMC Yukon Owner's Manual - Page 200

Air Bag Readiness Light There is an air bag readiness light on the instrument panel cluster, which shows the air bag symbol. The system checks the air bag's electrical system for malfunctions. The light tells you if there is an electrical problem. The system check includes the air bag sensors, the air bag modules, the passenger sensing system (if equipped), the wiring and the crash sensing and diagnostic module. For more information on the air bag system, see Air Bag Systems on page 1-71. This light will come on when you start your vehicle, and it will flash for a few seconds. Then the light should go out. This means the system is ready. If the air bag readiness light stays on after you start the vehicle or comes on when you are driving, your air bag system may not work properly. Have your vehicle serviced right away. Passenger Air Bag Status Indicator If your vehicle has the passenger sensing system your rearview mirror will have a passenger air bag status indicator. Passenger Air Bag Status Indicator - United States Passenger Air Bag Status Indicator - Canada When the ignition key is turned to RUN or START, the passenger air bag status indicator will light ON and OFF, or the symbol for on and off, for several seconds as a system check. Then, after several more seconds, the status indicator will light either ON or OFF, or either the on or off symbol to let you know the status of the right front passenger's frontal air bag. 3-42