Air Bag Systems: Service Precautions

Caution: In order to avoid deploying the air bag when troubleshooting the SIR system, use only the equipment specified and the instructions given. Failure to use the specified equipment as instructed could cause air bag deployment, personal injury to you or someone else, or unnecessary SIR system repairs.

The SIR Diagnostic System Check must always be the starting point of any SIR system diagnosis. The SIR Diagnostic System Check tests for proper AIR BAG warning lamp operation and inspects for SIR Diagnostic Trouble Codes (DTCs) using the scan tool. The following items describe the difference between current and history DTCs:
^ Current DTCs - Malfunctions that are presently being detected. Random Access Memory (RAM) stores the current DTCs. Turning the ignition switch to the OFF position erases current DTCs. The presence of a current DTC will cause the Inflatable Restraint Sensing and Diagnostic Module (SDM) to turn the AIR BAG warning lamp ON.
^ History DTCs - All malfunctions detected since the last clearing of history memory. Electrically Erasable Programmable Read Only Memory (EEPROM) stores the history DTCs. A scan tool clear codes command erases history DTCs.

Some DTCs are latched and cannot be cleared. Latched DTCs require the replacement of the SDM after proper diagnosis.

These diagnostic procedures will help you to find and repair SIR system malfunctions. This service category also contains information for repairing SIR system malfunctions. For best results, use the diagnostic tables, and follow the sequence listed below:
1. Perform the SIR Diagnostic System Check. All SIR diagnostics must begin with the SIR Diagnostic System Check. The SIR Diagnostic System Check determines the following results:
^ Proper AIR BAG warning lamp operation
^ Ability of the SDM to communicate through the data link connector (DLC)
^ Existence of SIR diagnostic trouble codes (DTC)
2. Refer to the diagnostic table as directed by the SIR Diagnostic System Check. The diagnostic tables will help enable you to diagnose any SIR system malfunction. Bypassing these procedures may result in the following problems:
^ Extended diagnostic time
^ Incorrect diagnosis
^ Incorrect parts replacement
3. Repeat the SIR Diagnostic System Check after you perform any repair or diagnostic procedures. This will verify that you correctly performed the repair. This will also ensure that no other malfunctions exist.