Side SIR System Description

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

The side supplemental inflatable restraint (SIR) system consists of the following components:

AIR BAG indicator located in the instrument panel cluster (IPC)
Inflatable restraint sensing and diagnostic module (SDM)
Inflatable restraint side impact sensors (SIS) (left/right)
Inflatable restraint roof rail modules (left/right)
Inflatable restraint wiring harnesses

The roof rail modules are located under the headliner extending from the front windshield pillar to the rear window pillar. 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 roof rail air bags deployment loop. The SDM, roof rail modules 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 modules deployment loop circuitry to prevent unwanted deployment of the air bag when servicing the inflator module.