The seat belt buckle switch is located within the seat belt buckle assembly and provides an input to the inflatable restraint sensing and diagnostic module (SDM). The SDM supplies a low reference circuit and a seat belt switch signal circuit to determine a buckled or unbuckled condition.

If the SDM determines the driver seat belt has not been buckled, the SDM will send a serial data message to the instrument panel clutch (IPC) to illuminate the seat belt warning indicator. If the SDM determines that a passenger is sitting in the passenger seat and the seat belt has not been buckled, the SDM will send a serial data message to the passenger presence system (PPS) display to illuminate the passenger seat belt warning indicator.

Schematic Reference

Seat Belt Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

SIR System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool Driver Seat Belt Switch parameter while buckling and unbuckling the driver seat belt. The parameter should change between Buckled and Unbuckled.

⇒	If the parameter does not cycle between the specified values, refer to Driver Seat Belt Switch Circuit Malfunction.

2. Ignition ON, seat belt unbuckled, verify the seat belt warning indicator is illuminated on the IPC.

⇒	If the indicator is not illuminated, replace the IPC.

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

Driver Seat Belt Switch Circuit Malfunction.

1. Ignition OFF, disconnect the harness connector at the driver seat belt switch.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal A and ground.

⇒	If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the SDM.

3. Ignition ON, verify the scan tool Driver Seat Belt Switch parameter is Unbuckled.

⇒	If not the specified value, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the SDM.

4. Install a 3A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool Driver Seat Belt Switch parameter is Buckled.

⇒	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the SDM.

5. If all circuits test normal, test or replace the seat belt buckle assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.