For 1990-2009 cars

### Diagnostic Trouble Codes

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.

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 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 ON the AIR BAG warning lamp.

• | History DTCs - All malfunctions detected since last clearing of history memory. Electrically Erasable Programmable Read Only Memory (EEPROM) stores the history DTCs. A scan tool clear codes command will erase history DTCs.

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

### Use of Special Tools

You should be familiar with the tools in this service category listed under the heading Special Tools. You should know how to measure voltage and resistance. Diagnosis requires proper use of the following tools:

• | The J-38125 Terminal Repair Kit

• | The J 38826 SIR Deployment Harness

• | The J 38715-A SIR Driver/Passenger Load Tool

• | The J 39200 Digital Multimeter

• | The J 35616 Connector Test Adaptor Kit

• | The J 39401-B SIR Deployment Fixture

• | The Scan Tool

• | The J 42113 SIR Shorting Bar Tool