Supplemental Restraint System (SRS)
The Supplemental Air Bag Restraint System is designed to provide increased collision protection for the driver IN ADDITION TO that provided by the driver 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 air bag
- Electrical system; including impact sensors, backup power supply and electronic diagnostic monitor assembly
Location of Air Bag System Components
1. LH Front Crash Sensor-LH front fender
2. RH Front Crash Sensor-RH front fender
3. Center Dash Panel Safing Sensor-Center cowl behind instrument panel
4. Driver Air Bag-Steering wheel
5. Center Front Sensor-Center radiator support
6. Clockspring-Behind steering wheel
7. Diagnostic Monitor-Under LH instrument panel adjacent to fuse panel
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's seat is unoccupied. The electrical system performs three main functions:
- Detects an impact
- Switches electric power to the igniter
- Monitors the system to determine readiness
The electrical system components include:
- Electronic diagnostic monitor with integrated backup power supply
- Air bag system readiness indicator
- Wiring harness and contact clockspring assembly
- Sensors
- Igniter assembly
Sensors
The primary crash sensor assembly is an electrical switch which reacts to impacts according to direction and force. It discriminates between impacts that require air bag inflation and impacts that do not require air bag inflation. When an impact occurs that requires air bag inflation, the sensor contacts close, completing the electrical circuit necessary for system operation.
At least two sensors, one safing, one crash, must be activated simultaneously to inflate the air bag. The air bag system is designed to operate in frontal or front-angled collisions. The air bag(s) should activate in a crash with severe frontal deceleration, more severe than hitting a parked car of similar size and weight head-on at about 28 mph (45 km/h).
Because the system senses the severity of the crash rather than vehicle speed, some frontal collisions at speeds above 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 air bag(s).
The primary sensors measure the crash severity while the safing sensor confirms the crash and is used to prevent inadvertent deployments possibly caused by a malfunction in the primary crash sensor circuits or crash sensors.