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.

Circuit/System Description

The inflatable restraint sensing and diagnostic module (SDM) sends the status of the passenger seat belt switch to the Passenger Air Bag ON/OFF indicator via a serial data communication message. The instrument panel cluster (IPC) controls the passenger seat belt indicator by using the serial data communication message from the SDM. If the seat belt is unfastened, only if an occupant is seated in the front passenger seat, the SDM will send a message to the instrument panel module (IPM) to illuminate the fasten safety belt indicator for 72 seconds or until the seat belt is fastened.

Reference Information

Schematic Reference

Seat Belt Schematics

Connector End View Reference

Seat Belt Connector End Views

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 seat belt switch - right
       • The SDM module
       • The seat belt switch - right wiring harness connector
       • The SDM wiring harness connector

  1. Observe the Passenger Air Bag ON/OFF status indicator. Turn ON the ignition, both ON and OFF indicators will turn ON for 5 seconds. Verify that the Passenger Air Bag ON/OFF status indicator illuminate.
  2. If the Passenger Air Bag ON/OFF status indicator does not illuminate refer to Passenger Presence System Indicator Circuit Malfunction .
  3. Sit in the front passenger seat with the ignition ON and observe the scan tool and Passenger Air Bag ON/OFF indicator, which contains the passenger seat belt indicator. Monitor the scan tool and passenger seat belt indicator while buckling and unbuckling the passenger seat belt. The passenger seat belt indicator should turn OFF and ON when the passenger seat belt is unbuckled and buckled. Verify that the passenger seat belt indicator turns ON and OFF.
  4. If the indicator does perform as described turn OFF the ignition, remove the SDM connector and the passenger/right seat belt buckle connector. Refer to SDM replacement in Repair Instructions for connector location.
    Test and repair both seat belt switch - right signal and ground circuits for an open, high resistance.
  5. If all circuits test normal then replace the seat belt pretensioner - right.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Seat Belt Buckle Pretensioner Replacement
    •  Control Module References for SDM replacement, setup, and programming.