GM Service Manual Online
For 1990-2009 cars only

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 provide an overview of each diagnostic category.

DTC Descriptors

DTC B0021 01: Right Front Side Deployment Loop Short to Battery

DTC B0021 02: Right Front Side Deployment Loop Short to Ground

DTC B0021 04: Right Front Side Deployment Loop Open Circuit

DTC B0021 0D: Right Front Side Deployment Loop Resistance Above Threshold

DTC B0021 0E: Right Front Side Deployment Loop Resistance Below Threshold

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

Side Impact Module - RF High Circuit

B0021 02

B0021 0D

B0021 04

B0021 01

B0021 0E

Side Impact Module - RF Low Circuit

B0021 02

B0021 0D

B0021 04

B0021 01

B0021 0E

Circuit/System Description

During a side or frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop in order to deploy the side impact module - RF. The SDM performs continuous diagnostic tests on the deployment loops to check for proper circuit continuity and for shorts to ground or voltage.

A shorting bar used within the side impact module - RF connector which will short together both side impact module - RF high and low circuits when the connector is disconnected, this will help to prevent unwanted deployment of the inflator module during servicing.

Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

Conditions for Setting the DTC

B0021 01

The side impact module - RF high and/or low circuit is short to voltage for 120 milliseconds.

B0021 02

The side impact module - RF high and/or low circuit is short to ground for 120 milliseconds.

B0021 04

The side impact module - RF high and/or low circuit is open for 120 milliseconds.

B0021 0D

The side impact module - RF deployment loop resistance is more than 3.9 ohms for 120 milliseconds.

B0021 0E

The side impact module - RF deployment loop resistance is less than 1.1 ohms for 120 milliseconds.

Action Taken When the DTC Sets

    • The SDM commands the AIR BAG indicator ON via serial data communications.
    • The SIR system is disabled and no deployments are allowed.

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 255 malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

SIR Schematics

Connector End View Reference

SIR Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Special Tools Required

    • J 38715-A Driver and Passenger SIR Load Tool
    • J 38715-30A SIR Load Tool Adapter

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 side impact module - RF
       • The side impact module wiring harness
       • The SDM module
       • The side impact module - RF wiring harness connector
       • The side impact module wiring harness connector
       • The SDM wiring harness connector

  1. Ignition OFF, disconnect the side impact module - RF wiring harness connector located under the driver front seat.
  2. Connect the J 38715-A to the harness side of the side impact module - RF wiring harness connector. Use the PASSENGER INFLATOR connector located on the load tool.
  3. Ignition ON, use a scan tool to observe the SIR DTC display. Verify DTC B0021 is set history.
  4. If DTC B0021 is current turn OFF the ignition and remove the SDM connector.
    Test and repair both side impact module - RF high and low circuits for a short to voltage, short to ground, or open/low resistance. If all circuits test normal then replace the SDM.
  5. Ignition OFF, disconnect and remove the J 38715-A . Then connect the side impact module - RF wiring harness connector. Remove the side impact module - RF connector. Use J 38715-30A to connect the J 38715-A to the harness side of the side impact module - RF connector. Use the PASSENGER INFLATOR connector located on the load tool.
  6. Ignition ON, use a scan tool to observe the SIR DTC display. Verify DTC B0021 is set history.
  7. If DTC B0021 is current the replace the side impact module - RF wiring harness.
  8. If DTC B0021 is history replace the side impact module - RF.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Driver and Passenger Seat Side Inflatable Restraint Module Replacement
    •  Inflatable Restraint Side Impact Module Wiring Harness Replacement
    •  SIR/SRS Wiring Repairs
    •  Control Module References for SDM replacement, setup, and programming