Side Impact Collision SRS Operation
When either the driver or passenger side impact side airbag sensor detects a sudden lateral acceleration which exceeds the lateral threshold value a signal is sent to the ORC. The ORC then deploys the appropriate side airbag.
The SRS electrical circuits are continuously monitored and controlled by a microprocessor and software contained within the Occupant Restraint Controller (ORC) (1). An airbag warning indicator lamp in the Instrument Cluster (IC) illuminates for about six seconds as a bulb test each time the ignition switch is turned to the On or Start positions. Following the bulb test, the airbag warning indicator lamp is turned On or Off by the ORC to indicate the status of the SRS. If the airbag warning indicator lamp comes on at any time other than during the bulb test, it indicates that there is a concern in the SRS electrical circuits. Such a problem may cause airbags to not deploy when required, or to deploy when not required.
Deployment of the driver and passenger airbags depends upon the angle and severity of an impact. Deployment is not based upon vehicle speed; rather, deployment is based upon the rate of deceleration as measured by the forces of gravity (G force). When an impact is severe enough, the microprocessor in the ORC signals the inflator of the appropriate airbag units to deploy their airbag cushions. The SBT is provided with a deployment signal by the ORC in conjunction with the driver and passenger airbags. During a frontal vehicle impact, the seat belts are used to restrain both the driver and the passenger in the proper position for an airbag deployment. The SBT removes the slack from the seat belts to provide further assurance that the driver and passenger are properly positioned and restrained for an airbag deployment.
Typically, the vehicle occupants recall more about the events preceding and following a collision than they do of an airbag deployment itself. This is because the airbag deployment and deflation occur so rapidly. In a typical 30 mile-per-hour (48 kilometer-per-hour) barrier impact, from the moment of impact until the airbags are fully inflated takes about 40 milliseconds. Within one to two seconds from the moment of impact, the airbags are almost entirely deflated. The times cited for these events are approximations, which apply only to a barrier impact at the given speed. Actual times will vary somewhat, depending upon the vehicle speed, impact angle, severity of the impact, and the type of collision.
When the ORC monitors a concern in any of the SRS circuits or components, including the SBT, it stores a fault code or Diagnostic Trouble Code (DTC) in its memory circuit and sends an electronic message to the IC via the CAN to illuminate the airbag warning indicator. Proper testing of the SRS components, CAN data bus, ORC signals, and DTC information requires the use of a scan tool. Refer to the appropriate diagnostic information.
See the Owners Manual for more information regarding features, use, and operation of all of the factory-installed active restraints.