The body control module (BCM) monitors the courtesy lamp switch signal circuit in order to determine when the courtesy/dome lamps should be illuminated. When the BCM senses that the courtesy lamp switch signal circuit is grounded when the switch is activated, the BCM will directly illuminate the courtesy/dome lamps.

The battery voltage must be between 9-16 volts.

The BCM detects the courtesy lamp switch is active while the IP lamp dimmer switch at the dim position.

The courtesy/dome lamps will be inoperative.

Schematic Reference

Interior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Dimmer Switch Malfunction

1. Ignition OFF, disconnect the harness connector X1 at the headlamp switch.
2. Ignition OFF, test for less than 5.0 ohms between the low reference circuit terminal H 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 BCM.

3. Verify the scan tool Dimming Input parameter is less than 1.0 volt.

⇒	If greater than the specified range, test the signal circuit terminal G for a short to voltage. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, replace the headlamp switch.

Courtesy Lamp Switch Malfunction

1. Ignition OFF, disconnect the X1 harness connector at the headlamp switch.
2. Ignition ON, verify the scan tool Courtesy Lamp Switch parameter is Inactive.

⇒	If not the specified value, test the signal circuit terminal J for a short to ground. If the circuit tests normal, replace the BCM.

3. If all circuits test normal, replace the headlamp switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.