Side SIR System Description (Front)

Side SIR System Description (Front)
The side SIR system (front) 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 modules (LF/RF)
- Inflatable restraint side impact sensors (SIS) (left/right)
- Inflatable restraint wiring harnesses

The side impact modules (front) are located either in the front doors or in the outside portion of the front seat backs. The side impact modules contain a housing, inflatable air bag. initiating device, and a canister of gas generating material. The initiator is part of the side impact 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 side air bag. The SDM. side impact 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 side impact module (front) is equipped with a shorting bar located on the connector of the module. The shorting bar shorts the side impact module deployment loop circuitry to prevent unwanted deployment of the air bag when servicing the inflator module.

Inflatable Restraint Side Impact Sensor (SIS)
The side impact sensor (SIS) contains a sensing device (accelerometer) which monitors vehicle acceleration and velocity changes to detect side collisions that are severe enough to warrant air bag deployment. The SIS is not part of the deployment loop, but instead provides an input to the SDM. The SDM contains a microprocessor that performs calculations using the measured accelerations and compares these calculations to a value stored in memory. When the generated calculations exceed the stored value, the SDM will cause current to flow through the deployment loops deploying the side air bags.

Inflatable Restraint Wiring Harness
The inflatable restraint wiring harnesses connect the inflators modules, SDM, deployment loops, and class 2 serial data together using weather pack connectors. SIR system connectors are yellow in color for easy identification. When repairing the SIR wiring harnesses follow the proper testing and wiring repair procedures listed.