The supplemental inflatable restraint (SIR) system supplements the protection offered by the occupant seat belt system. The SIR system has several inflater modules located throughout the vehicle, i.e. The inflatable restraint steering wheel module, inflatable restraint IP module in passenger side of dash,
and the inflatable restraint side impact module - LF and RT. 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 with the assistance of various sensor inputs. When the SDM detects a collision of sufficient force, it will process the information provided by the sensors to further support inflater module deployment. 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 code and inform the driver by commanding the instrument panel cluster (IPC) to turn the AIR BAG indicator ON. The steering column and knee bolsters are designed to absorb energy and compress during frontal collisions in order to limit leg movement and decrease the chance of injury to the driver and front passenger.