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 B0100: Front End Sensor 1 Performance (Left)

DTC B0101: Discard Front End Sensor 1 (Left)

DTC B0102: Incorrect Front End Sensor 1 Installed (Left)

DTC B0103: Front End Sensor 2 Performance (Right)

DTC B0104: Discard Front End Sensor 2 (Right)

DTC B0105: Incorrect Front End Sensor 2 Installed (Right)

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

Front End Sensor Left Signal

--

--

B0100

--

--

Front End Sensor Left Voltage

B0100

B0100

B0100

B0100

B0100

Front End Sensor Right Signal

--

--

B0103

--

--

Front End Sensor Right Voltage

B0103

B0103

B0103

B0103

B0103

Circuit/System Description

The inflatable restraint front end sensor utilizes a unidirectional 2-wire circuit. The front end sensor modulates current on the interface to send ID, State of Health, and deployment commands to the inflatable restraint sensing and diagnostic module (SDM). The SDM serves as a power source and a ground for the front end sensor. When the ignition is turned ON and input power from the SDM is first detected, the SIS responds by performing internal diagnostics and sending an ID to the SDM. The SDM considers the ID to be valid if the response time is less than 5 seconds. The front end sensor continually communicates status messages to the SDM, which determines if a fault is present in the front end sensor circuit. When a fault is detected, the SDM resets the front end sensor twice by removing and reapplying power to it. If the fault is still present, the SDM will set a DTC.

Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

Conditions for Setting the DTC

All of the following conditions exist for 2.5 seconds:

B0100 for Front End Sensor 1 or B0103 for Front End Sensor 2

    • A valid ID message is not received within 5 seconds of the front end sensor being powered up.
    • The SDM has not received a message from the front end sensor for more than 375 milliseconds.
    • The SDM has reset the front end sensor twice without detecting a valid ID message.

B0101 for Front End Sensor 1 or B0104 for Front End Sensor 2

    • The SDM has received an ID message from the front end sensor, which does not match the ID stored in the SDM memory.
    • The SDM has reset the front end sensor twice without detecting a correct ID message.

B0102 for Front End Sensor 1 or B0105 for Front End Sensor 2

The SDM has received a NOK message from the front end sensor.

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 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

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

Circuit/System Testing

Important: Refer to SIR Service Precautions.

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

   • Front end sensor
   • SDM module
   • Front end sensor wiring harness connector
   • SDM wiring harness connector

  1. Ignition OFF, disconnect the harness connector at the SDM and the appropriate front end sensor.
  2. Ignition ON, test for less than 1-volt between the front end sensor signal circuit terminal B and ground.
  3. If greater than the specified range, test the circuit for a short to voltage.
  4. Ignition ON, test for less than 1-volt between the front end sensor low reference circuit terminal A and ground.
  5. If greater than the specified range, test the circuit for a short to voltage.
  6. Test for infinite resistance between the front end sensor signal circuit terminal B and ground.
  7. If less than the specified value, test the circuit for a short to ground.
  8. Test for less than 1 ohm between the front end sensor signal circuit terminals listed below:
  9. • Right front end sensor terminal B and SDM harness connector terminal B8.
    • Left front end sensor terminal B and SDM harness connector terminal B5.
    If greater than the specified range, test the signal circuit for an open/high resistance.
  10. Test for less than 1 ohm between the front end low reference circuit terminals listed below:
  11. • Right front end sensor terminal A and SDM harness connector terminal B7.
    • Left front end sensor terminal A and SDM harness connector terminal B6.
    If greater than the specified range, test the low reference circuit for an open/high resistance.
  12. If all circuits test normal, replace the appropriate front end sensor.
  13. Reconnect all SIR components. Ignition ON, verify the DTC does not set as current.
  14. If the DTC resets as current , replace the SDM.

Repair Instructions

    •  Inflatable Restraint Front End Sensor Replacement
    •  SIR/SRS Wiring Repairs
    •  Control Module References for SDM replacement, setup, and programming

Repair Verification

Ignition ON, use the scan tool to clear the DTCs then recheck for DTCs. Verify no DTCs are set.

If DTC B0100 or B0103 was current replace the SDM.