GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The body control module (BCM) receives a ground signal from a door jamb or cargo lamp switch requesting cargo lamp illumination. When this occurs, the BCM directly sends a voltage through the courtesy lamp supply voltage circuit illuminating the cargo lamp.

Conditions for Running the DTC

The battery voltage must be between 9.0-16.0 volts.

Conditions for Setting the DTC

    • When the BCM receives a cargo lamp illumination request signal and the courtesy lamp supply voltage circuit is shorted to ground.
    • When the BCM is not receiving a cargo lamp illumination request signal and the courtesy lamp supply voltage circuit is shorted to voltage.
    • There is a loss of the underhood fuse block TBC battery supply voltage to the BCM for more than 1 second.

Action Taken When the DTC Sets

The cargo lamp will not operate or is always on.

Conditions for Clearing the MIL/DTC

    • This DTC will clear on current status after the condition for setting the fault is corrected.
    • A history DTC will clear after 100 consecutive ignition cycles without a fault present.
    • History and current DTC(s) can be cleared using a scan tool.

Diagnostic Aids

Perform a visual inspection for loose or poor connections at all related components. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step test determines if the problem exists in the wiring.

  2. This step determines if a condition exist in the TBC battery voltage supply circuit.

  3. After replacement of the BCM you must calibrate the new module for proper operation.

Step

Action

Yes

No

Schematic Reference: Interior Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views or Body Control System Connector End Views in Body Control System

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Test the courtesy lamp supply voltage circuit for a short to voltage or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 3

3

Test the TBC battery positive supply voltage circuit for a short to ground, open or high resistance. Refer to Circuit Testing in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 4

4

Inspect for poor connections at the harness connectors of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 5

5

Important: Perform the setup procedure for the body control module (BCM).

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 6

--

6

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK