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).

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.

#### Scan Tool Diagnostics

No provisions for scan tool diagnostics exist.

#### Flash DTC Diagnostics

Flash DTC diagnostics read current DTCs. You can enable FLASH DTC diagnostics by jumping the Data Link Connector (Underhood) terminal 11 (Tc) and terminal 3 (E1) with the ignition switch set to the ON position. This action pulls the SDM connector C2 terminal 15 to ground and signals the SDM to enter the FLASH DTC diagnostic display mode.

The SDM displays the DTCs by flashing the AIR BAG warning lamp. Each DTC that is displayed consists of the following:

• | A series of flashes which represent the tens (first) DTC digit

• | A 2.5 second pause

• | A series of flashes which represent the ones (second) DTC digit

Each DTC is flashed once before moving on to the next DTC. After all the DTCs are displayed, the entire DTC sequence is continually repeated until you remove the jumper from the DLC.

If there are no DTCs present, the SDM will flash the AIR BAG warning lamp continuously. This indicates that FLASH DTC diagnostics have been enabled. The SDM will continue to flash the AIR BAG warning lamp until the jumper wire is removed from the DLC.

#### How to Clear DTCs

All DTCs are cleared with each ignition cycle.

### 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 39200 Digital Multimeter (DMM)

• | The J 38826 SIR Deployment Harness

• | The J 35616 Connector Test Adapter Kit