Frontal SIR System

The SIR system consists of the following components:
^ AIR BAG indicator located in the Instrument Panel Cluster (IPC)
^ Driver and passenger knee bolsters
^ 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 harness
^ Seat belt pretensioner - LF
^ Seat belt pretensioner - RF
^ Steering wheel and steering column

A frontal collision of sufficient force will deploy the inflator modules and the seat belt pretensioners. 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 deployment loops, deploying the inflator modules and the seat belt pretensioners. Once the inflator modules are inflated, they quickly deflate through the vent holes and/or the fabric. After the inflator modules have deployed, the SDM sets a deployment commanded DTC and then turns the AIR BAG indicator ON. The SDM, IP module, steering wheel module, steering wheel module coil, seat belt pretensioner - LF, seat belt pretensioner - RF, and the connecting wires make up 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.