SIR Diagnostic Trouble Code Logic

CAUTION: In order to avoid deploying the air bag when troubleshooting the SIR system, use only the equipment specified in this manual and the instructions given in this manual. 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.

DIAGNOSTIC TROUBLE CODES (DTCs)
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 using the scan tool. The following describes the difference between current and history diagnostic trouble codes:
^ Current diagnostic trouble codes-Malfunctions that are presently being detected. RAM (Random Access Memory) stores the current diagnostic trouble codes. Turning the ignition switch to the OFF position erases current diagnostic trouble codes. The presence of a current diagnostic trouble code will cause the inflatable restraint Sensing and Diagnostic Module (SDM) to turn ON the AIR BAG warning lamp.
^ History diagnostic trouble codes-All malfunctions detected since last clearing of history memory. Electrically Erasable Programmable Read Only Memory (EEPROM) stores the history diagnostic trouble codes. A scan tool CLEAR CODES command will erase history diagnostic trouble codes.
Some diagnostic trouble codes are latched and can not be cleared. Latched diagnostic trouble codes will require replacement of the SDM after proper diagnostics.