Frontal SIR System Description

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The frontal supplemental inflatable restraint (SIR) system consists of the following components:

AIR BAG indicator located in the instrument panel cluster (IPC)
Inflatable restraint sensing and diagnostic module (SDM)
Inflatable restraint passenger presence system (PPS)
Inflatable restraint Passenger AIR BAG ON/OFF indicator
Inflatable restraint instrument panel (I/P) module
Inflatable restraint steering wheel module
Inflatable restraint steering wheel module coil
Inflatable restraint seat belt retractor pretensioners
Inflatable restraint wiring harnesses
Steering wheel and column
Driver and front passenger knee bolsters

A frontal collision of sufficient force will deploy the frontal air bags and/or pretensioners. The sensing and diagnostic module (SDM) contains a sensing device that converts vehicle velocity changes to an electrical signal. The SDM compares these signals to values stored in memory. If the signals exceed a stored value, the SDM will determine the severity of the impact and either cause current to flow through the frontal deployment loops deploying the frontal air bags and pretensioners, or it will deploy the pretensioners only. The SDM, I/P module, steering wheel module, steering wheel module coil, seat belt retractor pretensioners, and the connecting wires make up the frontal deployment loops. The SDM continuously monitors the deployment loops for malfunctions and illuminates the AIR BAG indicator if a fault is detected.