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.