Air Bag Systems: Description and Operation

Fig. 5 Air bag electrical system:

The air bag is powered directly from the battery. The system can function with the ignition switch in any position, including ``Off'' and ``Lock.'' The system can also function when no one is sitting in the driver's seat. The electrical system performs three main functions; it detects an impact, switches electric power to the igniter assembly and monitors the system to determine readiness.
The electrical system components include an electronic monitor assembly, air bag system readiness indicator lamp, wiring harness, sensors and an igniter assembly, Fig. 5.