Frontal SIR System Description

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

The frontal SIR system consists of the following components:

Inflatable Restraint Sensing and Diagnostic Module (SDM)
Inflatable Restraint Steering Wheel Module
Inflatable Restraint Steering Wheel Module Coil
Inflatable Restraint IP Module
Inflatable Restraint Side Impact Module - Left
Inflatable Restraint Side Impact Module - Right
Seat Belt Pretensioner - LF
Seat Belt Pretensioner - RF
Inflatable Restraint Side Impact Sensors
AIR BAG Indicator in the Instrument Panel Cluster

The inflatable restraint sensing and diagnostic module (SDM), inflatable restraint steering wheel module coil, inflatable restraint steering wheel module, inflatable restraint IP module, seat belt pretensioner - LF, seat belt pretensioner - RF, and the connecting wires make up the frontal deployment loops. The function of the frontal deployment loops is to supply current through the frontal inflator modules and the pretensioners to cause deployment in the event of a mild-to-severe frontal collision. Deployment occurs when the SDM detects vehicle velocity changes severe enough to warrant deployment.

The SDM contains a sensing device (accelerometer) that converts vehicle velocity changes to an electrical signal. The SDM compares this electrical signal to a value stored in memory. When the generated signal exceeds the stored value, the SDM performs additional signal processing and compares the generated signals to values stored in memory. When two of the generated signals exceed the stored values, the SDM will allow current to flow through the frontal inflator modules and the pretensioners causing deployment.