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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2009 🢒 Lucerne 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Seat Belt Indicator Circuit Malfunction - Driver

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.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Left Front Seat Belt Switch Signal

1

2

2

--

Low Reference

--

2

--

--

  1. Seat belt warning lamp remains ON.
  2. Seat belt warning lamp remains OFF.

Circuit/System Description

The driver seat belt switch is a 2-wire switch wired to the inflatable restraint sensing and diagnostic module (SDM) using a signal circuit and a low reference circuit. When the seat belt is unbuckled the switch is closed, and when the seat belt is buckled the switch is open. The SDM sends the status of the driver seat belt via serial data to the instrument panel cluster (IPC). After receiving the message, the IPC controls the illumination of the driver seat belt indicator.

Reference Information

Schematic Reference

    •  Seat Belt Schematics
    •  SIR Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Seat Belt 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 Verification
  1. Ignition ON, perform the IPC Display Test using the scan tool and verify the driver seat belt indicator is illuminated.
    2. ⇒If the indicator does not illuminate, replace the IPC.
  2. Monitor the Driver Seat Belt Switch parameter while connecting and disconnecting the seat belt. The parameter should display Buckled and Unbuckled as appropriate.

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 IPC
       • Left seat belt switch
       • Left seat belt switch harness connector
       • SDM
       • SDM harness connector

  1. Ignition OFF, disconnect the harness connector at the seat belt switch - left.
  2. Ignition ON, using a scan tool, verify the Driver Seat Belt Switch parameter in Supplemental Inflatable Restraints is Buckled.
    3. ⇒If the parameter is Unbuckled, test the signal circuit for a short to ground. If the circuit tests normal replace the SDM.
  3. Install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Driver Seat Belt Switch parameter is Unbuckled.
    4. ⇒If the parameter is Buckled, test the signal and the low reference circuits for high resistance/open or a short to voltage. If the circuits test normal, replace the SDM.
  4. If all circuits test normal, test or replace the applicable seat belt switch - left.

Component Testing
  1. With the seat belt buckled, test for infinite resistance between the signal circuit terminal A and the low reference terminal B.
    2. ⇒If not the specified value, replace the left seat belt switch.
  2. With the seat belt unbuckled, test for less than 2 ohms of resistance between the signal circuit terminal A and the low reference terminal B.
    3. ⇒If greater than the specified range, replace the left seat belt switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Seat Belt Buckle Replacement
    •  Inflatable Restraint Instrument Panel Module Indicator Replacement
    •  Control Module References for SDM and IPC replacement, setup, and programming