B2557

DTC B2557

CIRCUIT DESCRIPTION
The body control module (BCM) receives a ground signal from the door jamb or dome lamp switches requesting courtesy/dome lamp illumination. When this occurs, the BCM directly sends a voltage through the inadvertent power supply voltage circuit illuminating the courtesy/dome lamps.

DTC DESCRIPTORS
This diagnostic procedure supports the following DTCs:
- DTC B2557 Passenger Compartment Lamp Control Circuit Low
- DTC B2558 Passenger Compartment 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 courtesy lamp illumination request signal and the inadvertent power supply voltage circuit is shorted to ground
- When the BCM is not receiving a courtesy lamp illumination request signal and the inadvertent power 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 courtesy/dome lamps will not operate or are 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.

TEST DESCRIPTION

Step 1 - Step 6:

The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if the problem exists in the wiring.
3. This step determines if a condition exist in the TBC battery voltage supply circuit.
5. After replacement of the BCM, you must calibrate the new module for proper operation.