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.

### DTC Descriptors

DTC B2557: Passenger Compartment Lamp Control Circuit Low
DTC B2558: Passenger Compartment Lamp Control Circuit High

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Courtesy Lamp B+ | B2557 00 | 1 | -- | --
Cargo Lamp Signal | 1 | 1 | 1 | --
Dome Lamp Overide Switch Signal | 1 | 1 | 1 | --
Door Ajar Switch SIgnal | 1 | 1 | 1 | --
Interior Lamp Signal | 1 | 1 | 1 | --
Courtesy Lamp Control | 1 | 1 | B2558 00 | --
Dimmer Switch Low Reference | 1 | 1 | 1 | --
Cargo Lamp Ground - Left | -- | 1 | -- | --
Cargo Lamp Ground - Right | -- | 1 | -- | --
Door Switch Ground | -- | 1 | -- | --
Dome Lamp Ground | -- | 1 | -- | --
I/P Courtesy Lamp Ground - Left | -- | 1 | -- | --
I/P Courtesy Lamp Ground - Right | -- | 1 | -- | --
1. Courtesy Lamp Malfunction

### Circuit/System Description

The interior courtesy lamps consist of the dome lamp, reading lamps, cargo lamps, and the left and right footwell lamps. Battery voltage is supplied to the courtesy lamps by the body control module (BCM) through an inadvertent power supply circuit. In the event that any of these lamps were to remain illuminated for a period of more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power supply to prevent a total battery discharge condition. Courtesy lamp operation is controlled by the BCM through low side drive control circuits, and any time the inadvertent power supply is active the BCM turns on the courtesy lamps by grounding the control circuits. The BCM will activate the courtesy lamps using inputs from the dome lamp switch on the headlamp switch assembly or any of the door jamb switches. The dome lamp switch signal is monitored from battery voltage by the BCM and when the switch is turned on the signal circuit will be closed to the headlamp switch low reference circuit.

### Conditions for Running the DTC

The battery voltage must be between 9-16 volts.

### Conditions for Setting the DTC

#### B2557

The courtesy lamp supply circuit is shorted to ground.

#### B2558

The courtesy lamp control circuit is shorted to voltage.

### Action Taken When the DTC Sets

The courtesy lamps will not operate or will remain always on.

### Conditions for Clearing the 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.

### 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 Testing

1. Ignition OFF, disconnect the harness connector at the inoperative courtesy or dome lamp bulb.
2. Ignition ON, verify that a test lamp illuminates between the courtesy lamp supply circuit terminal A and ground.

⇒ | If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal , test or replace the BCM.

3. Connect a test lamp between the control circuit terminal B and courtesy lamp supply circuit terminal A. 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 ground. If the circuit tests normal, replace the BCM.

⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Dome Lamp Replacement

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