For 1990-2009 cars

### 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.

### Circuit/System Description

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.

### Reference Information

#### 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

• | 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, observe the function of the seat belt indicator while commanding the I/P lamps ON and OFF with a scan tool. The seat belt indicator 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 passenger seat occupied, buckle and unbuckle the passenger 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.

### Circuit/System Testing

#### Seat Belt Indicator Always ON

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

#### Seat Belt Indicator Always OFF

1. Ignition OFF, disconnect the harness connector at the passenger seat belt buckle.
2. Connect a fused jumper wire between the seat belt switch signal circuit terminal B and ground.
3. Ignition ON, verify the scan tool Passenger 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.

4. Connect a fused jumper wire between the seat belt switch signal circuit terminal B and the low reference terminal A.
5. Verify the scan tool Passenger Seat Belt Switch parameter is Buckled.

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

6. If all circuits test normal, test or replace the passenger seat belt buckle.

### Component Testing

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

⇒ | If not the specified value, replace the passenger seat belt buckle.

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

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Front Seat Belt Buckle Replacement

• | Control Module References for SDM and IPC replacement, setup, and programming