Air Bag: Description and Operation

The inflator modules consist of an inflatable bag and an inflator. An inflator consists of a canister of gas-generating material and an initiating device. The initiator is part of the deployment loop. When the vehicle is in a frontal crash of sufficient force, the inflatable restraint Sensing and Diagnostic Module (SDM) causes current to flow through the deployment loops. Current passing through the initiator ignites the material in the inflator module. The gas produced from this reaction rapidly inflates the air bag.

There is a shorting bar on the inflatable restraint steering wheel module side of the upper steering column connector that connects the inflatable restraint steering wheel module coil to the inflatable restraint steering wheel module. The shorting bar shorts across the inflatable restraint steering wheel module circuits during the disconnection of the upper steering column connector. The shorting of the inflatable restraint steering wheel module circuitry will help prevent unwanted deployment of the air bag when servicing the inflatable restraint steering wheel module, the steering column or other SIR system components.

There is a shorting bar on the inflatable restraint IP module connector that connects to the SIR wiring harness. The shorting bar shorts across the inflatable restraint IP module circuits during the disconnection of the inflatable restraint IP module connector. The shorting of the inflatable restraint IP module circuitry will help prevent unwanted deployment of the air bag when servicing the inflatable restraint IP module, the instrument panel or other SIR system components.

Some vehicles equipped with RPO ZX1 (driver seat only) use a trim cover instead of an inflatable restraint IP module. This trim cover contains a diagnostic resistor and a pigtail harness. The diagnostic resistor has a resistance value of 2 ohms. This 2 ohm value matches the internal resistance of an inflatable restraint IP module. The diagnostic resistor simulates the presence of an inflatable restraint IP module. This allows the inflatable restraint Sensing and Diagnostic Module (SDM) to sense the proper deployment loop resistance. If the diagnostic resistor malfunctions, the SDM will set the appropriate DTC. The trim cover pigtail harness allows connection to the inflatable restraint IP module harness connector.