Air Bag Warning Indicator
WARNING: This page is about a different car, the 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The instrument cluster is hardwired to the restraint control module (RCM). If an air bag system concern is detected, a diagnostic trouble code (DTC) is logged, and the RCM provides a ground path to the instrument cluster, turning on the air bag indicator.