Description & Operation

WARNING: This page is about a different car, the 2004 Ford Focus. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Accidental air bag deployment is possible. Personal injury may result. Read and follow all WARNINGS and AIR BAG SAFETY PRECAUTIONS before working on air bag system or related components.

The Supplemental Restraint System (SRS), also known as air bag system, is designed to provide increased accident protection for driver and passenger by deploying air bags in a front-end collision or side air bags in a side collision. The air bags, stored in center of steering wheel, instrument panel above glove box and in driver"s and passenger"s seat back, deploy in about 40 milliseconds after impact sensors close. Air bag system is designed to be used with 3-point seat belts.

During a front-end collision, the Restraints Control Module (RCM), also known as air bag control module, uses inputs from front impact sensor to discriminate between an event that warrants air bag deployment and an event that does not. Using inputs from left front seat track position sensor and seat belt switches in conjunction with front impact sensor inputs, RCM determines which air bags to deploy and at what deployment rate. In a crash of sufficient force, the RCM signals the first stage air bag modules and seat belt pretensioners to simultaneously deploy. Second stage driver- and passenger-side front air bag charges will ignite between 10-100 milliseconds after first stage ignition. Deployment at 100 milliseconds has negligible effect on the air bag inflation, but is used as a disposal function to eliminate subsequent deployments.

During a side or lateral collision, the RCM, using inputs from right and/or left side crash sensor, discriminates between an event that warrants air bag deployment and an event that does not. In a collision of sufficient force, the RCM signals the right and/or left seat air bag module(s) to deploy.

Air bag system includes the following components: RCM, back-up power supply (located inside the RCM), right- and left side crash sensors (attached to floor under outboard side of front seats), dual-stage driver-side air bag module, dual-stage passenger-side air bag module, side air bag modules (located behind outboard bolster of driver and passenger seat backs), left front seat belt retractor pretensioner and right front seat belt buckle pretensioner, seat belt switches, driver seat track position sensor, AIR BAG warning light, front impact sensor, ignitor assemblies (located in air bag modules), clockspring and associated wiring harnesses. See COMPONENT LOCATIONS .