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.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Low Reference | -- | 2 | -- | --
Seat Belt Switch Signal | 1 | 2 | -- | --
Ignition 1 Voltage | 3 | 3 | -- | --
Passenger Seat Belt Indicator Control | 4 | 5 | -- | --

1. The passenger seat belt indicator will remain ON with seat occupied and the seat belt buckled.
2. The passenger seat belt indicator will not illuminate with the seat occupied and the seat belt unbuckled, but will illuminate for the bulb test.
3. No indicator on the hazard warning and accessory switch will illuminate at any time.
4. The passenger seat belt indicator will illuminate at all times.
5. The passenger seat belt indicator will never illuminate but the PPS ON/OFF indicator does.

### Circuit/System Description

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 cluster (IPC) to illuminate the seat belt 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 control a high output to the hazard warning and accessory module to illuminate the passenger seat belt indicator.

### Reference Information

#### Schematic Reference

• | Seat Belt Schematics

• | Seat Belt Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

SIR System Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

• | Connector Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, observe the scan tool Passenger Seatbelt Status parameter while buckling and unbuckling the passenger seat belt. The parameter should change between Buckled and Not Buckled.

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

2. Ignition ON, while sitting in the passenger seat with the seat belt unbuckled, verify the passenger seat belt indicator is illuminated on the hazard warning and accessory switch display.

⇒ | If the indicator is not illuminated, replace the hazard warning and accessory switch.

### Circuit/System Testing

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

• | The SDM

• | The SDM wiring harness connector

• | The seat belt buckle

• | The seat belt buckle wiring harness connector

#### Passenger Seat Belt Switch Circuit Malfunction.

1. Ignition OFF, disconnect the harness connector at the passenger seat belt switch.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal A X1 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 Passenger Seat Belt Switch parameter is Not Buckled.

⇒ | If not the specified value, test the signal circuit terminal B X1 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 X1 and the low reference circuit terminal A X1. 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.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Seat Belt Retractor Pretensioner Replacement - Front

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