GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The body control module (BCM) controls the courtesy lamps theater dimming. The BCM grounds the lamps directly. The ground will slowly reduce in order to turn the lamps to the OFF position. If there is an open or a short to ground condition in the courtesy lamp control circuit, DTC  B2457 will set.

Conditions for Setting the DTC

The BCM detects a short to ground or an open in the courtesy lamp control circuit for more than 0.15 seconds.

Action Taken When the DTC Sets

    • Stores DTC B2457 in the BCM memory.
    • No driver warning message will be displayed for this DTC.

Conditions for Clearing the DTC

    • The short to ground is no longer detected by the BCM on the courtesy lamp control circuit.
    • An open circuit is no longer detected by the BCM on the courtesy lamp control circuit.
    • A history DTC clears after 50 consecutive ignition cycles if the condition for the fault is no longer present.

Test Description

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

  1. This step test the courtesy lamp control circuit for a short to ground or and open circuit.

Step

Action

Yes

No

Schematic Reference: Interior Lights Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Test the courtesy lamp control circuit of the body control module (BCM) for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 5

Go to Step 3

3

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 5

Go to Step 4

4

Important:: Perform the setup procedure for the BCM. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 5

--

5

  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