Air Bag Warning Indicator
WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. 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 illuminating the air bag indicator.