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
--- | --- | --- | --- | ---
Cargo Lamp Switch Signal | B2562 00 | 1 | B2563 00 | --
Cargo Lamp Control | 2 | 2 | 2 | --
Headlamp and Panel Dimmer Switch Low Reference | -- | 1 | -- | --
Cargo Lamp Ground - Left | -- | 2 | -- | --
Cargo Lamp Ground - Right | -- | 2 | -- | --

1. Cargo Lamp Switch Malfunction
2. Cargo Lamp Malfunction

### Circuit/System Description

The cargo lamps are supplied voltage by a dedicated courtesy lamp supply voltage circuit or by turning the cargo lamp switch ON. When the cargo lamp switch is turned to the ON position or the door is opened, voltage is then supplied to cargo lamps by the BCM through the headlamp and panel dimmer switch. The cargo lamps are grounded at all times at G105.

### Diagnostic Aids

Verify proper operation of the courtesy and dome lamps prior to diagnosing a cargo lamp condition.

### 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. Ignition ON, verify that the Cargo Lamp Switch parameter displays Active and Inactive while pressing and releasing the cargo lamp switch.

⇒ | If the scan tool parameter does not change between the commanded state, refer to Cargo Lamp Switch Malfunction.

2. Ignition ON, command the Courtesy Lamps ON and OFF with a scan tool. The cargo lamps should turn ON and OFF between the commanded states.

⇒ | If the cargo lamps do not turn ON and OFF, refer to the Cargo Lamp Malfunction.

### Circuit/System Testing

#### Cargo Lamp Switch Malfunction

1. Ignition OFF, disconnect the headlamp and panel dimmer switch connector.
2. Test for less than 5 ohms between the low reference circuit terminal 3 and ground.

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

3. Ignition ON, verify that the scan tool Cargo Lamp Switch parameter displays Inactive.

⇒ | If the parameter displays Active test the control circuit terminal 10 for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3A fused jumper wire between the control circuit terminal 10 and the ground circuit terminal 3. Verify the scan tool Cargo Lamp Switch parameter displays Active.

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

5. If the circuits test normal, test or replace the headlamp and panel dimmer switch.

#### Cargo Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative cargo lamp bulb.
2. Test for less than 5 ohms between the ground circuit terminal B 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 A and the ground circuit terminal B.
4. Command the Courtesy Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF.

⇒ | 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 an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, test or replace the inoperative bulb.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Headlamp Switch Replacement

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