GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2006 🢒 LaCrosse 🢒 Restraints 🢒 SIR 🢒 DTC B0040, B0041, or B0045

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 B0040: Left Front Side Deployment Loop Resistance Low

DTC B0041: Left Front Side Deployment Loop Open

DTC B0045: Left Front Side Deployment Loop Voltage Out of Range

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Roof Rail Module - Left High Circuit

B0045

B0045

B0041

B0040

Roof Rail Module - Left Low Circuit

B0045

B0045

B0041

B0040

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 roof rail module - left. 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 roof rail module - left connector which will short together both roof rail module - left 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

B0040

The roof rail module - left deployment loop resistance is less than 1.3 ohms for 500 milliseconds.

B0041

    • Roof rail module - left high circuit is less than 2.4 volts and the roof rail module - left deployment loop is more than 6 ohms for 500 milliseconds.
    • Roof rail module - left deployment loop resistance is more than 4.8 ohms for 500 milliseconds.

B0045

    • Roof rail module - left high and/or low circuits is short to ground or short to voltage for 500 milliseconds.
    • Roof rail module - left high circuit is less than 2.4 volts and roof rail module - left deployment loop resistance is less than 6 ohms for 500 milliseconds.

Action Taken When the DTC Sets
    • The SDM commands the AIR BAG indicator ON via serial data communication.
    • 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.

Diagnostic Aids

If there is more than one DTC set diagnose the open DTC first.

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 SIR Driver/Passenger 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 roof rail module - left
       • The SDM module
       • The roof rail module - left wiring harness connector
       • The SDM wiring harness connector

  1. Ignition OFF, remove the left garnish molding and disconnect the roof rail module connector.
  2. Use the J 38715-30A to connect the J 38715-A to the harness side of the roof rail module 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 B0040, B0041, or B0045 is set in current.
    4. ⇒If DTC B0040, B0041, or B0045 is history replace the roof rail module - left.
  4. Ignition OFF, disconnect and remove both the J 38715-A and adapter.
  5. Disconnect the SDM harness connector.
  6. Test and repair the high and low circuits between the SDM and roof rail module - left for a short to voltage, short to ground, open/high resistance, or short together. Verify that a short to voltage, short to ground, open/high resistance, or short together does not exist.
    7. ⇒If any of the above conditions are found make the appropriate repair.
  7. If all circuits test normal then replace the SDM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Inflatable Restraint Roof Side Rail Module Replacement - Left Side
    •  SIR/SRS Wiring Repairs
    •  Control Module References for SDM replacement, setup, and programming