The inflatable restraint sensing and diagnostic module (SDM) sends the status of the driver seat belt switch to the instrument panel cluster (IPC) via a serial data communication message. If the seat belt is unfastened, the SDM will send a message to the IPC to illuminate the fasten safety belt indicator for 72 seconds or until the seat belt is fastened.

Schematic Reference

Seat Belt Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Seat Belt System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition ON, with a scan tool perform the IPC Display Test and verify the driver seat belt indicator is illuminated for 5 seconds.

⇒	If the indicator does not illuminate, replace the IPC.

2. Monitor the SDM Driver Seat Belt Switch parameter while connecting and disconnecting the seat belt. The parameter should display Buckled and Unbuckled when changing seat belt states.

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

•	The SDM module

•	The seat belt switch left wiring harness connector

•	The SDM wiring harness connector

1. Ignition OFF, disconnect the harness connector at the seat belt switch.
2. Test the resistance between the switch ground circuit terminal B (buckle side) and switch signal circuit terminal A (buckle side) while connecting and disconnecting the seat belt. The resistance should switch between infinity and less than 5 ohms.

⇒	If the resistance does not switch as indicated, replace the seat belt buckle.

3. Verify a test lamp illuminates between the switch ground circuit terminal B (harness side) and B+.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

4. Ignition OFF, disconnect the harness connector at the SDM.
5. Ignition ON, test for less than 1 volt between the SDM seat belt switch signal circuit terminal A14 and ground.

⇒	If greater than the specified range, test the signal circuit for a short to voltage.

6. Test for infinite resistance between the SDM seat belt switch signal circuit terminal A14 and ground

⇒	If less than the specified value, test the signal circuit for a short to ground.

7. Test for less than 2 ohms of resistance in the seat belt switch signal circuit between SDM harness connector terminal A14 and the seat belt switch harness connector terminal A.

⇒	If greater than the specified range, test the signal circuit for an open/high resistance.

8. If the circuits test normal, replace the SDM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.