Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

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).

Schematic Reference

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

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

⇒	If not Off, test the headlamps off 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 Key In Ignition Cylinder parameter is No.

⇒	If not No, test the key in ignition switch signal circuit for an open or short to voltage. If the circuit tests normal, replace the ignition switch.

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

⇒	If any parameter displays Door Ajar, go to Courtesy Lamps Always On .

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.