For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Circuit Description

When the ignition is turned ON, the instrument panel cluster (IPC) flashes the AIR BAG indicator seven times. The inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within the SIR system. If no SIR system malfunctions exists, the SDM will request the IPC to turn the AIR BAG indicator off after it has flashed 7 times. The AIR BAG indicator is controlled by the SDM via class 2 serial data.

### Diagnostic Aids

• | If ignition 1 voltage for the SDM is outside of the normal operating voltage range (9-16 volts), the AIR BAG indicator will illuminate with no DTC set.

• | The loss of serial data communication between the SDM and the IPC will cause the AIR BAG indicator to illuminate. Refer to DTC U1001-U1254.

### Reference Information

#### Schematic Reference

SIR Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

SIR System Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Testing

1. Ignition ON, with a scan tool, verify the Battery Voltage Signal Parameter is 9-16 volts.

⇒ | If not the specified range, refer to Diagnostic System Check - Vehicle.

2. Ignition OFF, monitor the IPC, ignition ON. The SIR warning indicator should flash then turn OFF.

⇒ | If the SIR warning indicator continually flashes, program the SDM.

⇒ | If the SIR warning indicator remains on steady, test for DTCs and refer to Diagnostic Trouble Code (DTC) List - Vehicle. If no DTC is current, proceed to the next step.

3. With a scan tool, perform the Display Test in Instrument Panel Cluster/Special Functions. The Air Bag indicator should turn ON and OFF as commanded.

⇒ | If the air bag indicator does not illuminate as expected, replace the IPC.

4. If all tests are normal, replace the SDM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | SIR/SRS Wiring Repairs

• | Control Module References for SDM and IPC replacement, setup, and programming