SIR System Overview

WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT: This manual covers both the Buick Rendezvous and the Pontiac Aztek. The difference is the Buick has been equipped with the dual stage inflator modules, front end sensor (EFS) and seat belt pretensioners. The Pontiac only has single stage inflator modules and no EFS or seat belt pretensioners. The proper section should be used for the vehicle being serviced.

The supplemental inflatable restraint (SIR) system supplements the protection offered by the occupant seat belt system (2). The SIR system has several inflator modules that are located throughout the vehicle. They are the following:

Fig 1: Illustrating Deployed Inflatable Restraint

Courtesy of GENERAL MOTORS CORP.

Inflatable restraint steering wheel module (1)
Inflatable restraint I/P module (1)
Inflatable restraint side impact module-LF
Inflatable restraint side impact module-RF
Inflatable restraint seat belt pretensioner-LF, Buick
Inflatable restraint seat belt pretensioner-RF, Buick

Each inflator module has a deployment loop that is controlled by the inflatable restraint sensing and diagnostic module (SDM), which is mounted inside the vehicle. The SDM determines the severity of a collision with the assistance of various sensor inputs. When the SDM detects a collision of sufficient force, it processes the information provided by the sensors to further support air bag or pretensioner deployment. The SDM will deploy the frontal air bags and pretensioners if it detects a collision of sufficient force. If the force of the impact is not sufficient to warrant inflator module deployment, the SDM may still deploy the seat belt pretensioners. The SDM performs continuous diagnostic monitoring of the SIR system electrical components. Upon detection of a circuit malfunction, the SDM will set a diagnostic trouble code (DTC) and inform the driver by commanding the instrument panel cluster (IPC) to turn the AIR BAG indicator ON. The steering column and knee bolsters (3) are designed to absorb energy and compress during frontal collisions in order to limit leg movement and decrease the chance of injury to the driver and front passenger.