Air Bag Systems: Description and Operation

The passive supplemental air bag restraint system is designed to provide increased collision protection for front seat occupants in addition to that provided by the three point safety belt system.

- Safety belt use is necessary to obtain the best occupant protection and to receive the full advantages of the supplemental air bag.
- Ford recommends the use of safety belt systems for all vehicle occupants.

The supplemental air bag restraint system consists of two basic subsystems:

- driver side air bag module and passenger side air bag module
- electrical system, including RH primary crash front air bag sensor and bracket, LH primary crash front air bag sensor and bracket and air bag diagnostic monitor

The subsystem components are located as follows:

- LH primary crash Front Air Bag Sensor and Bracket - LH side of support
- RH primary crash Front Air Bag Sensor and Bracket - RH side of support
- safing sensor - integral with air bag diagnostic monitor
- driver side air bag module - steering wheel
- passenger side air bag module - above glove compartment
- air bag sliding contact - behind steering wheel
- air bag diagnostic monitor and bracket - center of the instrument panel above A/C evaporator housing

Electrical System
The air bag system 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 the driver or passenger seats are unoccupied. The electrical system performs three main functions:
- detects an impact
- carries electric current to the igniter(s)
- monitors the system to determine readiness

The electrical system components include:
- air bag diagnostic monitor with integrated back-up power supply and safing sensor.
- air bag warning indicator.
- wiring harness and air bag sliding contact
- RH primary crash front air bag sensor and bracket, LH primary crash front air bag sensor and bracket.
- igniter within the driver side air bag module and passenger side air bag module.

The air bag system is designed to:
- operate in frontal or front-angled collisions.
- activate the air bags in a crash with severe frontal deceleration, more severe than hitting a parked car of similar size and weight head-on at about 45 km/h (28 mph).
- sense the severity of the crash rather than vehicle speed, thus some frontal collisions at speeds above 45 km/h (28 mph) may not be severe enough to require air bag inflation.

The sensors in the vehicle determine if air bag inflation is required in the following manner:

1. During severe frontal deceleration caused by an impact that decelerates the vehicle in the forward direction, both a primary crash sensor and a safing sensor will activate.
2. When a primary and safing sensor are closed at the same time, electrical current will flow igniting the driver side air bag module and passenger side air bag module.

The primary sensors measure the crash severity while the safing sensor confirms the crash. The safing sensor is used to prevent inadvertent deployments possibly caused by a malfunction in the primary crash sensor circuits or crash sensors.