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.

### 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.

### 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 Verification

1. Verify that the courtesy lamp switch parameter displays Active and Inactive while operating the headlamp and panel dimmer switch ON and OFF.

⇒ | If the scan tool parameter does not display Active and Inactive when switching between the commanded states, refer to Courtesy Lamp Switch Malfunction.

2. Verify that all Door Ajar Switchs display Door Ajar and Door Closed while opening and closing the doors.

⇒ | If the scan tool parameter does not display Door Ajar or Door Closed in relation to the actual switch position, refer to Door Jamb Switch Malfunction.

3. Command the Courtesy Lamps ON and OFF with a scan tool. The lights should turn ON and OFF between the commanded states.

⇒ | If the lights do not turn ON and OFF, refer to the Courtesy Lamps Malfunction.

### Circuit/System Testing

#### Courtesy Lamp Switch Malfunction

1. Ignition OFF, disconnect the headlamp and panel dimmer switch connector.
2. Test for less than 5 ohms between the low reference circuit terminal 3 and ground.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance.

3. Ignition ON, verify that the scan tool courtesy lamp switch parameter displays Inactive.

⇒ | If the parameter displays Active test the courtesy lamp signal circuit terminal 11 for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3A fused jumper wire between the courtesy lamp signal circuit terminal 11 and the ground circuit terminal 3. Verify the scan tool courtesy lamp switch parameter displays 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 the circuits test normal, test or replace the headlamp and panel dimmer switch.

#### Door Jamb Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the driver door jamb switch.
2. Ignition OFF, Door Closed, test for less than 5.0 ohms between the ground circuit terminal 2 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the appropriate door ajar switch parameter is Door Closed.

⇒ | If not the specified value, test the signal circuit terminal 1 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 1 and the ground circuit terminal 2. Verify the Door Ajar Switch parameter is Door Ajar with a scan tool..

⇒ | 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 appropriate door ajar switch.

#### Courtesy Lamp Malfunction

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.

• | Headlamp Switch Replacement

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