For 1990-2009 cars

### 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.

### DTC Descriptors

This diagnostic procedure supports the following DTCs:

• | DTC B2562 Cargo Lamp Control Circuit Low

• | DTC B2563 Cargo Lamp Control Circuit High

### Conditions for Running the DTC

The battery voltage must be between 9-16 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 truck body controller (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 DTCs 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 .

### Test Description

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

1. This step 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 Data Communication Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Test the courtesy lamp supply voltage circuit for a short to voltage or short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 6 | Go to Step 3
3 | Test the truck body controller (TBC) battery positive supply voltage circuit for a short to ground, open, or high resistance. Refer to Circuit Testing . 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 body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 6 | Go to Step 5
5 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. 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