Frontal SIR System Description

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The frontal SIR system consists of the following components:

AIR BAG indicator located in the instrument panel cluster (IPC)
Inflatable restraint electronic frontal sensor (EFS), if vehicle is equipped with dual stage air bags
Inflatable restraint IP module
Inflatable restraint sensing and diagnostic module (SDM)
Inflatable restraint steering wheel module
Inflatable restraint steering wheel module coil
Inflatable restraint wiring harnesses
Steering wheel and column

A frontal collision of sufficient force will deploy the frontal air bags. The SDM contains a sensing device (accelerometer) that converts vehicle velocity changes to an electrical signal. In the event of a frontal collision, the SDM receives a signal from the electronic frontal sensor, which assists the SDM in determining the severity of the collision. The SDM compares these signals to a value stored in memory. When the generated signals exceed the stored value, the SDM will cause current to flow through the frontal deployment loops simultaneously deploying the frontal air bags. The SDM, IP module, steering wheel module, steering wheel module coil and the connecting wires makeup the frontal deployment loops. The SDM continuously monitors the deployment loops for malfunctions and turns the AIR BAG indicator ON if a fault is detected.