Frontal SIR System Description

The frontal SIR system consists of the following components:
1. AIR BAG indicator in the Instrument Panel Cluster (IPC)
2. Driver and front passenger knee bolsters
3. Inflatable restraint Instrument Panel (IP) module
4. Inflatable Restraint Sensing And Diagnostic Module (SDM)
5. Inflatable restraint steering wheel module
6. Inflatable restraint steering wheel module coil

A frontal collision of sufficient force will deploy the frontal inflator modules. The SDM contains a sensing device (accelerometer) that converts vehicle velocity changes to an electrical signal. The SDM contains a microprocessor, which performs calculations using the measured accelerations and compares these calculations to a value stored in memory. When the generated calculations exceed the stored value, the SDM will cause current to flow through the frontal deployment loops, deploying the frontal inflator modules. Once the inflator modules are inflated, they quickly deflate through the air bag vent holes and/or the bag fabric. After the inflator modules are deployed, the SDM sets a deployment commanded DTC and then commands the IPC to turn the AIR BAG indicator ON. The SDM, IP module, steering wheel module, steering wheel module coil and the connecting wires make up the frontal deployment loops. The SDM continuously monitors the deployment loops for malfunctions and commands the IPC to turn the AIR BAG indicator ON if a fault is detected.