The Supplemental Inflatable Restraint (SIR) system, also known as Airbags, supplement the protections offered by the driver and front passenger seat belt system. The Airbag system deploys an air bag from the center of the steering wheel and from the right side of the instrument panel on models with this option. The system also incorporates what is called a knee bolster. This does exactly what is says, protects your knees during a crash. The steering column also absorbs crash energy. The driver and passenger knee bolsters are below the instrument panel.
Newer models can have many more bags on the sides, called side curtain. They can be in the front and rear of the passenger compartment. Higher end vehicles can have as many as 0 or more Airbags.
Damage will occur to the steering column and right side of the dash board and possibly the windshield. But, the system is used to save lives not car parts.
The SIR system consists of the following components:
| • | Inflatable Restraint Sensing and Diagnostic Module (SDM) |
| • | Inflatable Restraint Steering Wheel Module |
| • | Inflatable Restraint Steering Wheel Module Coil |
| • | Inflatable Restraint IP Module |
| • | AIR BAG warning lamp in the instrument cluster |
| • | Side Curtain Airbags |
| • | Rear Passenger Airbags |
The inflatable restraint Sensing and Diagnostic Module (SDM), inflatable restraint steering wheel module coil (SIR coil assembly), inflatable restraint steering wheel module (driver inflator module), inflatable restraint IP module (passenger inflator module), and connector wires make up the deployment loops. The function of the deployment loops is to supply current through the inflators modules, which will cause deployment of the air bags. Deployment occurs when the SDM detects vehicle velocity changes severe enough to warrant deployment.
The module contains a sensing device Accelerometer that converts vehicle speed velocity changes to an electrical signal that is sent to the module. The SDM then compares this electrical signal to a value stored in it's memory. When the generated signal exceeds the stored value, the SDM performs additional signals processing steps and compares this generated signal to the values stored in memory. When two of these generated signals exceed the stored values, the Airbag module will cause current to flow through the modules at the same time to deploy the air bags.
