SIR Diagnostic Trouble Code Logic

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 checks for proper AIR BAG warning lamp operation and checks 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.