The inflatable restraint sensing and diagnostic module (SDM) sends the status of the driver and passenger seat belt switch to the instrument panel cluster (IPC) via a serial data communication message. If the seat belt of an occupied seat 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, observe the function of the seat belt indicator lamp while commanding the I/P lamps ON and OFF with a scan tool. The seat belt indicator lamp should turn ON and OFF when changing between the commanded states.

⇒	If the seat belt indicator is always OFF, replace the I/P cluster

2. Ignition ON, with the appropriate seat occupied, buckle and unbuckle the appropriate seat belt, the seat belt indicator should go ON and OFF while buckling and unbuckling the occupied seat.

⇒	If the seat belt indicator lamp is always ON, refer to Seat Belt Indicator Always ON.

⇒	If the seat belt indicator lamp is always OFF, refer to Seat Belt Indicator Always OFF.

Seat Belt Indicator Always ON

1. Ignition OFF, disconnect the harness connector at the appropriate seat belt buckle.
2. Ignition ON, verify the scan tool 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.

3. If all circuits test normal, test or replace the appropriate seat belt buckle.

Seat Belt Indicator Always OFF

1. Ignition OFF, disconnect the harness connector at the appropriate seat belt buckle.
2. Connect a fused jumper wire between the seat belt switch signal circuit terminal B and the seat position sensor return circuit terminal A.
3. Ignition ON, verify the scan tool Seat Belt Switch parameter is Buckled.

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

4. If all circuits test normal, test or replace the appropriate seat belt buckle.

1. Ignition OFF, disconnect the harness connector at the appropriate seat belt buckle.
2. Test for infinite resistance between the signal terminal B and the return circuit terminal A with the seat belt buckle unbuckled.

⇒	If not the specified value, appropriate seat belt buckle.

3. Test for less than 2.0 ohms between the signal terminal B and the return circuit terminal A with the seat belt buckle buckled.

⇒	If greater than the specified range, replace the appropriate seat belt buckle.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.