For 1990-2009 cars

### Circuit Description

The courtesy lamps consist of the dome lamp and the rearview mirror reading lamps. Battery positive voltage for the courtesy lamps is supplied by the body control module (BCM). The BCM controls the courtesy lamps by providing ground to the courtesy lamps low control circuit. If the courtesy lamps low control circuit becomes shorted to voltage, DTC B2558 sets.

### Conditions for Running the DTC

At least one of the following conditions must exist:

• | At least one door is open.

• | The courtesy lamps are commanded on by the BCM.

### Conditions for Setting the DTC

• | The courtesy lamps are commanded on by the BCM.

• | The courtesy lamp control circuit is shorted to voltage for 125 milliseconds.

### Action Taken When the DTC Sets

• | DTC B2558 is stored in the BCM memory.

• | The BCM disables the courtesy lamp control output for the remainder of the ignition cycle.

### Conditions for Clearing the DTC

• | The conditions for setting the DTC are no longer present.

• | A history DTC clears after 100 malfunction free ignition cycles.

• | The BCM receives the clear code command from the scan tool.

### Diagnostic Aids

If the DTC is a history DTC, the problem may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

### Test Description

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

1. The normal state of the INTERIOR LAMP OUTPUT parameter with a door open is ON.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Interior Lights Schematics
1 | Did you perform the Lighting System Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Lighting Systems
2 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the courtesy lamps on and off.

Do the courtesy lamps turn on and off with each command?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3 |

1. Turn OFF the ignition.
2. Disconnect the BCM connectors.
3. Turn ON the ignition, with the engine OFF.
4. Test for a short to voltage in the courtesy lamp low control circuit. Refer to Circuit Testing and Wiring Repairs 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 connector 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 set up procedure for the body control module. Replace the body control module. 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