SIR Diagnostic Flow

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 (DTC) using the scan tool. The following describes the difference between current and history SIR DTCs:
^ Current SIR DTCs - Malfunctions that are presently being detected. Random Access Memory (RAM) stores the current SIR DTCs. Turning the ignition switch to the OFF position erases current SIR DTCs. The presence of a current SIR DTC will cause the Inflatable Restraint Sensing and Diagnostic module (SDM) to turn ON the AIR BAG warning lamp.
^ History SIR DTCs - All malfunctions detected since last clearing of history memory. Electrically Erasable Programmable Read Only Memory (EEPROM) stores the history SIR DTCs. A scan tool clear codes command will erase history SIR DTCs.

Some SIR DTCs are latched and can not be cleared. Latched SIR DTCs will require replacement of the SDM after proper diagnostics.