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
--- | --- | --- | --- | ---
Courtesy Lamp Control | 2 | 2 | 1 | --
Courtesy Lamp Control | -- | 2 | -- | --
1. Courtesy lamps always illuminated 2. Courtesy lamps do not illuminate

### Circuit/System Description

Battery voltage for the courtesy lamps is supplied at all times to the body control module (BCM). When the BCM receives a signal to command the courtesy lamps ON, it then applies voltage through the dome/reading lamps and compartment courtesy lamp control circuit.

### Reference Information

#### 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

• | 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. Observe the driver information center while opening and closing each vehicle door and the liftgate. The driver information center should display the door ajar/liftgate ajar message only when the door/liftgate is open.

⇒ | If the driver information center displays the door ajar/liftgate ajar message when a door or the liftgate is closed, refer to Door Ajar Indicator Malfunction.

⇒ | If the door ajar/liftgate is functioning normal, refer to Courtesy Lamp Circuit Malfunction.

### Circuit/System Testing

#### Courtesy Lamp Circuit Malfunction

1. Ignition OFF, disconnect the harness connector at the E8S Rear Compartment Courtesy Lamp.
2. Test for less than 5 Ω between the ground circuit terminal 2 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal 1 and the ground circuit terminal 2.
4. Command the Courtesy Lamps test ON and OFF with the scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module (BCM).

⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM).

5. If all circuits test normal, test or replace the E8S Rear Compartment Courtesy Lamp.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Dome Lamp Replacement

• | Dome Lamp Bulb Replacement

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