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
--- | --- | --- | --- | ---
B+, BCM X4 Terminal 2 | B2615 00 | B2615 00 | -- | --
B+, BCM X3 Terminal 2 | 3, 4 | 3, 4 | -- | --
Courtesy Lamp Control | B2615 00 | 1 | -- | --
Courtesy Lamp Defeat Signal | 1 | 5 | -- | --
Inadvertent Power Control | B1480 00 | 3 | -- | --
Courtesy Lamp Switch ON Signal | 2 | 2 | 1 | --
Inadvertent Courtesy Lamps Ground | -- | 1, 3 | -- | --
1. Courtesy/Reading Lamps Malfunction 2. Dome Lamp Switch Malfunction 3. Inadvertent Power Courtesy Lamps Malfunction 4. Interior Backlighting Malfunction 5. Courtesy Lamp Defeat Inoperative

### Circuit/System Description

The courtesy lamps are controlled by the body control module (BCM). Inputs from the dome lamp switch and the door ajar switches are monitored by the BCM. When a door ajar switch is closed, or the dome lamp switch is turned to the ON position, the BCM supplies the B+ for the courtesy lamps.

### 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 DIC while opening and closing each vehicle door and the liftgate. The DIC should display the door ajar/liftgate ajar message only when the door/liftgate is open.

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

2. Ignition ON, courtesy defeat switch in the OFF position, open and close each door while observing the scan tool Ctsy. Lamp Actv. Reason parameter. The parameter should change between Door Open and Off.

⇒ | If the parameter is always Manual Defeat, refer to Courtesy Defeat Switch Malfunction.

3. Courtesy lamps switch in the OFF position, all doors closed, verify the scan tool Ctsy. Lamp Actv. Reason parameter is Off.

⇒ | If the parameter is Manual, refer to Courtesy Lamps Switch Malfunction.

4. Command the Courtesy Lamps ON and OFF with the scan tool. All of the courtesy lamps should turn ON and OFF as commanded.

⇒ | If one or more of the courtesy lamps remains ON or OFF at all times, refer to Courtesy Lamp Malfunction.

### Circuit/System Testing

#### Courtesy Defeat Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Verify that a test lamp illuminates between the ground circuit terminal 8 and B+.

⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Ignition ON, all doors closed. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Off.

⇒ | If the parameter is Manual Defeat, test the courtesy defeat signal circuit terminal 9 for a short to ground. If the circuit tests normal, replace the BCM.

4. Connect a 3A fused jumper wire between the courtesy defeat signal circuit terminal 9 and ground.
5. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual Defeat.

⇒ | If not the specified value, test the signal circuit for an open/high resistance or short to voltage. If the circuit tests normal, replace the BCM.

6. If all circuits test normal, test or replace the headlamp switch.

#### Courtesy Lamps Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Verify that a test lamp illuminates between the ground circuit terminal 8 and B+.

⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Ignition ON, all doors closed. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Off.

⇒ | If the parameter is Manual , test the courtesy lamps on signal circuit terminal 12 for a short to ground. If the circuit tests normal, replace the BCM.

4. Connect a 3A fused jumper wire between the courtesy lamps on signal circuit terminal 12 and ground.
5. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual.

⇒ | If not the specified value, test the signal circuit for an open/high resistance or short to voltage. If the circuit tests normal, replace the BCM.

6. If all circuits test normal, test or replace the headlamp switch.

#### Courtesy Lamp Malfunction

1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 2 and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the circuit fuse is open, test the courtesy lamp control circuits for a short to ground.

3. Ignition OFF, connect the X4 harness connector at the BCM. Disconnect the harness connector at the appropriate courtesy lamp.
4. Verify that a test lamp illuminates between the appropriate ground circuit listed below and B+.

• | Liftgate courtesy lamps - terminal 1

• | All other courtesy lamps - terminal B

⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

5. Connect a test lamp between the appropriate control circuit listed below and ground:

• | Liftgate courtesy lamps - terminal 2

• | All other courtesy lamps - terminal A

6. Command the Courtesy Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF as commanded.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

7. If all circuits test normal, test or replace the courtesy lamp or courtesy lamp bulb.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Headlamp Switch Replacement

• | Reading Lamp Bulb Replacement

• | Instrument Panel Courtesy Lamp Bulb Replacement - Left Side

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