Airbag System/Occupant Restraint Controller System And Occupant Classification System: Notes

The Airbag System contains the following components: Occupant Restraint Controller (ORC), Air-bag Warning Indicator, Clockspring, Driver and Passenger dual squib Airbags, Driver and Passenger Seat belt Tensioner (SBT), Driver Knee Blocker Airbag, Left and Right Side Curtain Airbags, and Front and Side Impact Sensors. The ORC also monitors the Occupant Classification System (OCS) for the presence of a passenger in the front outer seat.

The Occupant Classification System contains the following components: Occupant Classification Module (OCM), Bladder and Sensor, Belt Tension Sensor, and Passenger Airbag off Indicator. The Occupant Restraint Controller (ORC) supports staged airbag deployment and remote impact sensing. Staged deployment is the ability to trigger airbag system squib inflators individually as needed to provide the appropriate restraint for the severity of the impact. The ORC has four major functions: PCI Bus communications, onboard diagnostics, impact sensing, and component deployment. The ORC also contains an energy-storage capacitor. This capacitor stores enough electrical energy to deploy the front airbag components for two seconds following a battery disconnect or failure during an impact. The ORC is secured to the floor panel transmission tunnel below the instrument panel inside the vehicle. The ORC cannot be repaired or adjusted. The ORC sends and/or receives PCI Bus messages with the Instrument Cluster (MIC), Body Control Module (BCM), and Pow-ertrain Control Module (PCM). Diagnostic trouble codes will be set if the communication with these modules is lost or contains invalid information. The microprocessor in the ORC monitors the front impact sensor signals and the airbag system electrical circuits to determine the system readiness. If the ORC detects a monitored system fault, it sends a message to the instrument cluster via PCI bus to turn on the Airbag Warning Indicator. The ORC can set both active and stored diagnostic trouble codes to aid in diagnosing system problems. See DIAGNOSTIC TROUBLE CODES .

The ORC uses an internal accelerometer, two front sensors and six side impact sensors, to sense the rate of vehicle deceleration and provide verification of the direction and severity of an impact. A pre-programmed decision algorithm in the ORC microprocessor determines when the deceleration rate is severe enough to require airbag system protection. The ORC also uses the driver and passenger seat belt switch status (buckled or unbuckled) to determine the level of driver airbag deployment, low, medium or high. When the programmed conditions are met, the ORC sends an electrical signal to deploy the appropriate airbag system components.

WARNING: THE AIRBAG SYSTEM IS A SENSITIVE, COMPLEX ELECTROMECHANICAL UNIT. BEFORE ATTEMPTING TO DIAGNOSE OR SERVICE ANY AIRBAG SYSTEM OR RELATED STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENTS YOU MUST FIRST DISCONNECT AND ISOLATE THE BATTERY NEGATIVE (GROUND) CABLE. WAIT TWO MINUTES FOR THE SYSTEM CAPACITOR TO DISCHARGE BEFORE FURTHER SYSTEM SERVICE. THIS IS THE ONLY SURE WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE TO DO THIS CAN RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY OR DEATH.

WARNING: NEVER STRIKE OR KICK THE OCCUPANT RESTRAINT CONTROLLER, AS IT CAN DAMAGE THE IMPACT SENSOR OR AFFECT ITS CALIBRATION. IF AN AIRBAG CONTROL MODULE IS ACCIDENTALLY DROPPED DURING SERVICE, THE MODULE MUST BE SCRAPPED AND REPLACED WITH A NEW UNIT. FAILURE TO TAKE THE PROPER PRECAUTIONS CAN RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND PERSONAL INJURY OR DEATH.

The Airbag Warning Indicator is the only point at which the customer can observe symptoms of a system malfunction. Whenever the ignition key is turned to the run or start position, the ORC performs a lamp check by turning the Airbag Warning Indicator on for 6-8 seconds. After the lamp check, if the indicator turns off, it means that the ORC has checked the system and found it to be free of discernible malfunctions. If the lamp remains on, there could be an active fault in the system or the MIC lamp circuit may be internally shorted. If the lamp comes on and stays on for a period longer than 6-8 seconds then goes off, there is usually an intermittent problem in the system.