Operation

OPERATION

In the Occupant Classification System (OCS) the passenger airbag on/off indicator gives an indication when the passenger airbag and seat belt tensioner deployment circuits are disabled by the Occupant Restraint Controller (ORC). This indicator is controlled by a transistor within the ORC through a hard wired output based upon ORC programming and electronic occupant classification messages received by the ORC over the Controller Area Network (CAN) data bus from the Occupant Classification Module (OCM).

The passenger airbag on/off indicator Light Emitting Diode (LED) is completely controlled by the ORC. The LED receives a battery current input on a fused ignition switch output (run) circuit. Therefore, the LED will always be OFF when the ignition switch is in any position except ON. The LED only illuminates when it is provided a path to ground by the ORC transistor. The ORC will turn ON the passenger airbag on/off indicator for the following reasons:

- Bulb Test - Each time the ignition switch is turned to the ON position the passenger airbag on/off indicator is illuminated for about six seconds.
- Child Seat Detected (or Load Less Than Minimum Weight Threshold) Occupant Classification Message - Each time the ORC receives an electronic message from the OCM indicating a child seat has been detected in the passenger side front seat (or that the seat load is less than a minimum weight threshold) the passenger airbag and seat belt tensioner deployment circuits are deactivated and the passenger airbag on/off indicator will be illuminated. The indicator remains illuminated until the ORC receives an occupant classification message indicating that the passenger side front seat is empty, that the seat is occupied by a load equal to or greater than a minimum weight threshold, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Load Undetermined Occupant Classification Message - Each time the ORC receives an electronic message from the OCM indicating that a load cannot be determined in the passenger side front seat, the passenger airbag and seat belt tensioner deployment circuits are deactivated and the passenger airbag on/off indicator will be illuminated. The indicator remains illuminated until the ORC receives an occupant classification message indicating that the passenger side front seat is empty, that the seat is occupied by a load equal to or greater than a minimum weight threshold, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Communication Error - If the ORC receives invalid occupant classification messages or no messages from the OCM, the passenger airbag on/off indicator is illuminated. The indicator remains illuminated until the ORC receives a valid message from the OCM indicating that the passenger side front seat is empty, that the seat is occupied by a load equal to or greater than a minimum weight threshold, or until the ignition switch is turned to the OFF position, whichever occurs first.

The ORC continually monitors the occupant classification messages from the OCM to decide whether the passenger airbag and seat belt tensioner deployment circuits should be activated or deactivated. Note that there may be several seconds of delay between changes in the detected occupant status and passenger airbag on/off indications. This is a programmed feature of the OCM used to prevent a flashing indicator condition resulting from the normal shifting of occupant weight on the passenger seat cushion. The ORC then provides the proper control output to turn the passenger airbag on/off indicator ON or OFF.

The ORC will store a Diagnostic Trouble Code (DTC) for any malfunction it detects. The hard wired circuits between the passenger airbag on/off indicator and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the passenger airbag on/off indicator or the electronic controls and communication between other modules and devices that provide features of the OCS. The most reliable, efficient, and accurate means to diagnose the passenger airbag on/off indicator or the electronic controls and communication related to passenger airbag on/off indicator operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.