Side SIR System Description (Front)

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The side Supplemental Inflatable Restraint (SIR) System (front) consists of the following components:

AIR BAG indicator located in the instrument panel cluster (IPC)
Inflatable restraint roof rail modules front/rear, (left/right)
Inflatable restraint sensing and diagnostic module (SDM)
Inflatable restraint side impact sensors (SIS) (left/right)
Inflatable restraint vehicle rollover sensor
Inflatable restraint wiring harnesses
Seat belt pretensioners (left/right)

The roof rail modules (front/rear) are located in the headliner along the roof rails. The roof rail modules contain a housing, inflatable air bag, initiating device, and a canister of gas generating material. The initiator is part of the roof rail module deployment loop. When a side impact of sufficient force occurs the SIS detects the impact and sends a signal to the SDM. The SDM compares the signal received from the SIS to a value stored in memory. When the generated signal exceeds the stored value, the SDM will cause current to flow through the side deployment loop deploying the roof rail air bag. The SDM, roof rail modules (front) and the connecting wires makeup the side deployment loops. The SDM continuously monitors the deployment loops for malfunctions and turns the AIR BAG indicator ON if a fault is present. Each roof rail module is equipped with a shorting bar located on the connector of the module. The shorting bar shorts the roof rail module deployment loop circuitry to prevent unwanted deployment of the air bag when servicing the inflator module.