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.

### DTC Descriptors

DTC B0090 0F: Rollover Sensor Erratic
DTC B0090 3A: Rollover Sensor Incorrect Component Installed
DTC B0090 39: Rollover Sensor Internal Electronic Failure
DTC B0090 71: Rollover Sensor Invalid Serial Data Received

### Circuit/System Description

The inflatable restraint vehicle rollover sensor (ROS) utilizes battery power supply and a bidirectional interface circuit. The ROS modulates current on the interface to send ID, State of Health, and deployment commands to the inflatable restraint sensing and diagnostic module (SDM). When the ignition is turned on the ROS responds by performing internal diagnostics and sending an ID to the SDM. The ROS continually communicates status messages to the SDM, which determines if a fault is present in the ROS circuit. If the fault is present, the SDM will set a diagnostic trouble code (DTC).

### Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

### Conditions for Setting the DTC

All of the following conditions must exist for 5 seconds:

#### B0090 0F

• | The SDM received a fault present message from the ROS.

• | The ROS is in assembly plant mode and the SDM is in production mode.

• | The SDM has not received any data from the ROS.

#### B0090 3A

• | The SDM has received an ID message from the vehicle rollover sensor which does not match the ID stored in the SDM memory.

• | The SDM has reset the vehicle rollover sensor twice without detecting the correct ID message.

#### B0090 39

• | The SDM has received a NOK message from the vehicle rollover sensor.

• | The SDM has not received a message.

#### B0090 71

The SDM has received invalid serial data from the vehicle rollover sensor.

### Action Taken When the DTC Sets

• | The SDM commands the AIR BAG indicator ON via serial data communications.

• | The side air bag deployment loops will be disabled for rollover events only. For side impact events the side air bags are still enabled.

### 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.

### Diagnostic Aids

If either the SDM or vehicle rollover sensor were replaced verify that the correct part numbers were used for the vehicle application and the components were properly configured. Refer to Control Module References for SDM and ROS setup and programming.

### Reference Information

#### Schematic Reference

SIR Schematics

#### Connector End View Reference

SIR 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

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

### Circuit/System Testing

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

• | The vehicle rollover sensor

• | The SDM module

• | The vehicle rollover sensor harness connector

• | The SDM wiring harness connector

1. For DTC B0090 39 replace the vehicle rollover sensor.
2. Ignition OFF, disconnect the harness connector at the rollover sensor and the SDM.
3. Ignition OFF, test for less than 1 ohm of resistance between the rollover sensor ground circuit terminal 6 and ground.

⇒ | If greater then the specified range, test the circuit for an open/high resistance.

4. Verify a test lamp illuminates between the rollover sensor B+ circuit terminal 1 and ground.

⇒ | If the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuit fuse is open, test the circuit for a short to ground.

5. Replace the inflatable restraint vehicle rollover sensor.
6. With a scan tool, clear the DTCs. Verify DTC B0090 is not set.

⇒ | If DTC B0090 is set replace the SDM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Inflatable Restraint Vehicle Rollover Sensor Replacement

• | SIR/SRS Wiring Repairs

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