Cargo Lamps Malfunction

Cargo Lamps Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.

Diagnostic Fault Information





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. Cargo lamp operation can controlled by a push-button switch on the instrument panel (I/P) that sends a momentary ground signal to the BCM. The BCM will then illuminate the cargo lamp only while the courtesy lamps are illuminated. The cargo lamps are grounded at all times at G105.

Reference Information
Schematic Reference

Interior Lights Schematics (Interior Lights Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Interior Lighting Systems Description and Operation (Interior Lighting Systems Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Cargo Lamp Switch parameter while activating the cargo lamp switch. The parameter should change between Active and Inactive.

If the parameter does not change between the commanded states, refer to Cargo Lamp Switch Malfunction.
If the parameter changes between the commanded states, refer to Cargo Lamps Malfunction.

Circuit/System Testing

Cargo Lamp Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition ON, verify that a test lamp illuminates between the low reference circuit terminal 3 and B+.

• If the test lamp does not illuminate, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM

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

• If not the specified value, test the signal 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 signal circuit terminal 10 and ground. Verify the scan tool Cargo Lamp Switch parameter is 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 all circuits test normal, test or replace the headlamp and panel dimmer switch.

Cargo Lamps Malfunction
1. Ignition OFF, disconnect the harness connector at the inoperative cargo lamp.
2. Ignition OFF, exterior lamps OFF, 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 cargo lamps ON and OFF with the cargo lamp switch. 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 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.

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

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Headlamp Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for BCM replacement, setup, and programming