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 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

Side Impact Module - LF High Circuit

B0045

B0045

B0041

B0040

Side Impact Module - LF 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 side impact module - LF. 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 - LF connector which will short together both side impact module - LF 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 side impact module - LF deployment loop resistance is less than 1.3 ohms for 500 milliseconds.

B0041

    • The side impact module - LF high circuit is less than 2.4 volts and the side impact module - LF deployment loop is greater than 6 ohms for 500 milliseconds.
    • The side impact module - LF deployment loop resistance is more than 4.8 ohms for 500 milliseconds.

B0045

    • The side impact module - LF high and/or low circuits has a short to ground or short to voltage for 500 milliseconds.
    • The side impact module - LF high circuit is less than 2.4 volts and side impact module - LF deployment loop resistance is less than 6 ohms for 500 milliseconds.

Action Taken When the DTC Sets

    • The SDM requests the instrument panel cluster (IPC) to illuminate the AIR BAG indicator.
    • The SIR system is disabled and no deployments are allowed.

Conditions for Clearing the DTC

    • The condition for setting the DTC no longer exists.
    • 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

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

Control Module References for scan tool information.

Special Tools

J 38715-A Driver/Passenger Load tool

Circuit/System Testing

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

   • Inflatable restraint module
   • SDM module
   • Front side impact module wiring harness connector
   • SDM wiring harness connector

Important: The connector and connector position assurance (CPA) may seat independent of each other. Both the connector and CPA should seat with an audible and/or tactile click. The CPA isolates the shoring-bars within the connector allowing the deployment circuit to operate properly.

  1. Verify that the LF inflatable restraint side impact module connector and CPA are engaged.
  2. If the above condition is not found, make the appropriate repair.
  3. Ignition OFF, disconnect the harness connector at the LF inflatable restraint side impact module.
  4. With the appropriate load tool adapter, connect J 38715-A in place of the LF inflatable restraint side impact module.
  5. Ignition ON, with a scan tool, verify that DTC B0040, B0041, or B0045 is set as current.
  6. If a DTC is not set or is set as history, cycle the ignition OFF, disconnect the load tool and adapter, reconnect the harness connector at the LF inflatable restraint side impact module, and cycle the ignition ON. If the DTC resets after reconnecting the module, replace the LF inflatable restraint side impact module.
  7. Ignition OFF, disconnect the load tool and the adapter.
  8. Disconnect the harness connector at the SDM.
  9. Ignition ON, test for less than 1.0 volt between the low control circuit terminal A and ground.
  10. If greater than the specified range, test the circuit for a short to voltage.
  11. Ignition ON, test for less than 1.0 volt between the high control circuit terminal B and ground.
  12. If greater than the specified range, test the circuit for a short to voltage.
  13. Ignition OFF, test for infinite resistance between the low control circuit terminal A and ground.
  14. If less than the specified value, test the circuit for a short to ground.
  15. Ignition OFF, test for infinite resistance between the high control circuit terminal C1 and ground.
  16. If less than the specified value, test the circuit for a short to ground.
  17. Test for less than 1.0 ohm between the low control circuit terminal A and the SDM terminal listed below:
  18. • With RPO code AJ7 terminal C2
    • With RPO code AW9 terminal 16
    If greater than the specified range, test the signal circuit for an open/high resistance.
  19. Test for less than 1.0 ohm between the high control circuit terminal B and the SDM terminal listed below:
  20. • With RPO code AJ7 terminal C1
    • With RPO code AW9 terminal 17
    If greater than the specified range, test the signal circuit for an open/high resistance.
  21. If all circuits test normal, replace the SDM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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