For 1990-2009 cars

### Diagnostic Instructions

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

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

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

### DTC Descriptors

DTC B1449 : Passenger Seat Occupant Classification Sensor Communication

### Circuit/System Description

When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform a turn-on test to diagnose critical malfunctions within the SDM itself.

Upon passing these tests, the ignition and deployment loop voltages are measured to ensure that these voltages are within the normal ranges. The SDM monitors the voltages at the driver low and the passenger low to detect shorts to ground or voltage in the deployment loops.

The SDM tests the wiring connection to extra devices, such as the side impact sensor, by letting an infinitesimal current flow through the internal circuit to verify the resistance. If the voltage is out of range, the SDM is unable to test the air bag system properly.

In the case of DTC B1103, test the battery and if necessary replace the battery with a new one. Erase the DTC using the scan tool.

### Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

### Conditions for Setting the DTC

The OC passenger system is defective or the air bag wiring harness is damaged.

### Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator ON.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

• | A history DTC will clear once 100 malfunction-free ignition cycles have occurred.

### Reference Information

#### Schematic Reference

SIR Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Circuit/System Testing

Note: When removing connectors inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector.

• | The steering wheel coil module

• | The SDM module

• | The steering wheel coil module wiring harness connector

• | The SDM wiring harness connector

1. Ignition OFF, disconnect the OC sensor connector
2. Disconnect the SDM connector.
3. Test for less than 1 ohm between terminal 64 of the SDM and the terminal 2 of the OC sensor.

⇒ | If resistance is not as specified, repair the open or high resistance in the circuit.

⇒ | If all circuits test normal, replace the OC Sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Steering Wheel Inflatable Restraint Module Coil Replacement

• | Steering Wheel Inflatable Restraint Module Replacement

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