SIR System Overview
The supplemental inflatable restraint (SIR) system supplements the protection offered by the occupant seat belt system (2). The SIR system contains various inflator modules located throughout the vehicle, i.e. inflatable restraint steering wheel module (1) and the inflatable restraint I/P module (1). Each inflator module has a deployment loop that is controlled by the inflatable restraint sensing and diagnostic module (SDM), which is mounted inside of the vehicle. The SDM determines the severity of a collision and commands deployment of each inflator module. The SDM performs continuous diagnostic monitoring of the SIR system electrical components. Upon detection of a circuit malfunction, the SDM will set a diagnostic trouble (DTC) and inform the driver by commanding the instrument panel cluster (IPC) to turn the AIR BAG indicator ON. The steering column and knee bolsters (3) are designed to absorb energy and compress during frontal collisions in order to limit leg movement and decrease the chance on injury to the driver and front passenger.