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
--- | --- | --- | --- | ---
Seat Belt Switch Signal | 1 | 2 | -- | --
Low Reference | -- | 2 | -- | --

1. Indicator will remain ON with seat belt buckled.
2. Indicator will illuminate during the bulb test.

### Circuit/System Description

The driver seat belt switch is a 2-wire switch wired to the inflatable restraint sensing and diagnostic module (SDM) using a signal circuit and a low reference circuit. When the seat belt is unbuckled the switch is closed, and when the seat belt is buckled the switch is open. The SDM sends the status of the driver seat belt via serial data to the instrument panel cluster (IPC). After receiving the message, the IPC controls the illumination of the driver seat belt indicator.

### Reference Information

#### Schematic Reference

• | Seat Belt Schematics

• | SIR 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, with a scan tool perform the Actuator Test in IPC ECU and verify the driver seat belt indicator is illuminated for 5 seconds.

⇒ | If the indicator does not illuminate, replace the IPC.

2. Monitor the SDM Driver Seatbelt Status parameter while connecting and disconnecting the seat belt. The parameter should display Buckled and Not Buckled when changing seat belt states.

### 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

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 Seatbelt Status parameter is Not Buckled.

⇒ | 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 Seatbelt Status 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.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the seat belt switch.
2. With the seat belt buckled, test for infinite resistance between the signal circuit terminal B and the low reference terminal A.

⇒ | If not the specified range, replace the seat belt switch.

3. With the seat belt unbuckled, test for less than 2 ohms between the signal circuit terminal B and the low reference terminal A.

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

### 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