Airbag Indicator

The airbag indicator gives an indication to the vehicle operator when the airbag system, or a circuit or component of the system is ineffective. The airbag indicator is controlled by a transistor on the IPC circuit board based upon IPC programming and electronic messages received by the IPC from the Occupant Restraint Controller (ORC) over the CAN data bus.

The airbag indicator LED is completely controlled by the IPC logic circuit, and that logic will only allow this indicator to operate when the IPC receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the LED will always be OFF when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided a path to ground by the IPC transistor. Each time the ignition switch is turned to the ON position the airbag indicator is illuminated for about six to eight seconds. The entire bulb test is a function of the ORC. The IPC will turn ON the airbag indicator for the following reasons:

• Airbag Indicator Lamp-On Message  - Each time the IPC receives an electronic airbag indicator lamp-ON  message from the ORC, the airbag indicator will be illuminated. The indicator remains illuminated for about 12 seconds or until the IPC receives a lamp-OFF message from the ORC, whichever is longer. This indicator will also be extinguished when the ignition switch is turned to the OFF position.
• Communication Error  - If the IPC receives no lamp-ON or lamp-OFF messages from the ORC for 10 consecutive message cycles, the airbag indicator is illuminated. The indicator remains illuminated until the IPC receives a single lamp-OFF message from the ORC.

The ORC continually monitors the airbag system circuits and sensors to decide whether the system is in good operating condition. The ORC then sends the proper lamp-ON or lamp-OFF message to the IPC. If the ORC sends a lamp-ON message after the bulb test, it indicates that the ORC has detected a system malfunction or that the airbags and seat belt tensioners may not deploy when required, or may deploy when not required. The ORC will store a DTC for any malfunction it detects. Each time the airbag indicator fails to illuminate due to an open or short in the IPC airbag indicator circuit, the IPC sends a message notifying the ORC of the condition, then the IPC and the ORC will each store a DTC.