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 radio generates the audible warning through the left front speaker. The radio receives audible warning requests via GMLAN serial data from the body control module (BCM).

### Reference Information

#### Schematic Reference

• | Instrument Cluster Schematics

• | Body Control System Schematics

#### Connector End View Reference

• | Displays and Gages Connector End Views

• | Data Communication Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Scan Tool Data List

### Circuit/System Testing

1. Ignition ON, headlamp switch OFF, verify the scan tool Headlamp Switch ON parameter is Inactive.

⇒ | If not Inactive, test the headlamps signal circuit for an open or short to voltage. If the circuit tests normal, replace the headlamp switch.

2. Ignition ON, park lamp switch OFF, verify the scan tool Park Lamp Switch parameter is Off.

⇒ | If not Off, test the park lamp switch signal circuit for an open or short to voltage. If the circuit tests normal, replace the headlamp switch.

3. Ignition OFF, key out of the ignition, verify the scan tool Ign. Off/Run/Crank parameter is Inactive.

⇒ | If not Inactive, test the key in ignition signal circuit for a short to ground. If the circuit tests normal, replace the ignition switch.

4. Ignition ON, doors closed, verify the scan tool Door Ajar Switch parameters show Door Closed.

⇒ | If not Door Closed, go to Courtesy Lamps Always On .

5. If all circuits test normal, replace the BCM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Ignition and Start Switch Replacement

• | Headlamp Switch Replacement

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