Supplemental Inflatable Restraint (Sir) System

The main portions of the SIR system are the deployment loop and Diagnostic Energy Reserve Module (DERM). The main function of the deployment loop is to supply current through inflator module (air bag module) in the steering wheel, which will cause deployment of air bag in the event of an accident severe enough to warrant deployment. The main function of the DERM is to supply sufficient voltage to inflator module, ensuring sufficient energy to deploy air bag for a few seconds if voltage is lost in an accident. A second function of the DERM is SIR diagnosis. If monitored voltages fall outside of expected limits, DERM will indicate a system fault by storing a malfunction code and illuminating INFLATABLE RESTRAINT indicator light.