GM Service Manual Online
For 1990-2009 cars only

Refer to Interior Lights Schematics .

Circuit Description

The interior lamps consist of the dome lamp, courtesy lamps and the rearview mirror reading lamps. Battery voltage for the interior lamps is supplied by the BCM through the inadvertent power relay (internal to the BCM) output. The interior lamps are controlled by the body control module (BCM) by grounding the interior lamps control circuit. If the interior lamps control circuit becomes shorted to battery voltage, DTC B2558 sets.

Conditions for Running the DTC

At least one of the following conditions must exist:

    â€¢ At least one door is open.
    â€¢ The interior lamps are commanded on by the BCM.

Conditions for Setting the DTC

    â€¢ The interior lamps are commanded on by the BCM.
    â€¢ The interior lamp control circuit is shorted to battery positive voltage for 125 milliseconds.

Action Taken When the DTC Sets

    â€¢ DTC B2558 is stored in the BCM memory.
    â€¢ The BCM disables the interior lamp control output for the remainder of the ignition cycle.

Conditions for Clearing the DTC

    â€¢ A current DTC B2558 will clear when the malfunction is no longer present and the ignition switch is cycled.
    â€¢ All BCM history codes clear after 100 ignition cycles with no current codes active within the 100 ignition cycles.
    â€¢ A scan tool can be used to clear the DTC.

Diagnostic Aids

If the DTC is a history DTC, the problem may be intermittent. Try performing tests while wiggling the wiring and connectors. This can often cause the malfunction to appear.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

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

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check - Lighting Systems ?

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 the control circuit of the interior lamps for a short to battery. 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 .

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