The inflatable restraint sensing and diagnostic module (SDM) sends a serial data communication message to the instrument panel module (IPC), the IPC then controls the status of the Passenger Air Bag ON/OFF indicator with this 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 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. With no weight in the passenger seat observe the passenger seat belt status indicator. Turn ON the ignition, the indicator should illuminate for 5 seconds.

⇒	If the indicator is always ON or always OFF, refer to Indicator Circuit Test.

2. Ignition ON and with the passenger seat occupied, observe the passenger seat belt status indicator while connecting and disconnecting the seat belt. The indicator should turn ON and OFF when changing seat belt states.

⇒	If the indicator illuminates incorrectly, refer to Switch Circuit Test.

Indicator Circuit Test.

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

•	The Passenger Air Bag ON/OFF indicator

•	The SDM module

•	The IPC wiring harness connector

•	The Passenger Air Bag ON/OFF indicator wiring harness connector

•	The SDM wiring harness connector

1. Ignition OFF, disconnect the harness connector at the inflatable restraint passenger air bag ON/OFF indicator.
2. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 4 and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test or replace the inflatable restraint passenger air bag ON/OFF indicator.

3. Connect a test lamp between the passenger seat belt indicator control circuit terminal 5 and the ignition circuit terminal 4.

Important: Allow 5 seconds after seat is occupied for test lamp to change states.

4. With the passenger seat occupied the test lamp should turn ON with the seat belt disconnected, and turn OFF with the seat belt connected.

⇒	If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the IPC.

⇒	If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit tests normal, replace the IPC.

5. If the circuits test normal, replace the inflatable restraint passenger air bag ON/OFF indicator.

Switch Circuit Test

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 seat belt switch harness connector

•

The SDM

•	The SDM harness connector

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

⇒	If not as specified, 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 A16 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 A16 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 A16 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.