Frontal SIR System

The frontal SIR system consists of the following components:
^ An inflatable restraint Sensing And Diagnostic Module (SDM).
^ An inflatable restraint steering wheel module (steering wheel air bag).
^ An Inflatable restraint steering wheel module coil.
^ An inflatable restraint IP Module (IP air bag).
^ An AIR BAG Warning Lamp in the Instrument Panel Cluster (IPC).

The inflatable restraint sensing and diagnostic module (SDM), inflatable restraint steering wheel module coil, inflatable restraint steering wheel module, inflatable restraint IP module, 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, deploying the frontal inflator modules simultaneously. 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 generates signals to values stored in memory. When two of the generated signals exceed the stored values, the SDM will cause current to flow through the frontal inflator modules deploying the frontal inflator modules.