GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2002 🢒 Grand Prix 🢒 DTC 🢒 DTC 003

Circuit Description

The body control module (BCM) controls the interior illumination. The BCM turns on the interior (courtesy) lamps when the following actions occur:

    • Any of the vehicle doors are opened.
    • The instrument panel dimmer switch is turned to the DOME position.
    • Exit illumination is active.
    • The doors are unlocked through the keyless entry system (BCM type 3 and type 4 only).
    • The doors are unlocked using the door key cylinder (BCM type 4 only).

The BCM turns the interior lamps off when all the vehicle doors are closed and the instrument panel dimmer switch is in the OFF position.

All the vehicle doors contain a door lock ajar switch. When the driver door is open, the left front door lock ajar switch closes and sends a ground signal to the BCM through the driver door ajar input circuit.

When one of the right front, left rear, or right rear doors is open, its corresponding door lock ajar switch closes and sends a ground signal to the BCM through the corresponding door ajar input circuit. The BCM grounds the courtesy lights control output circuit when detecting a ground signal in any of the following circuits:

    • Driver door ajar input circuit
    • Passenger door ajar input circuit

When the driver door is closed, the left front door lock ajar switch opens the driver door ajar input circuit. When all of the right front, left rear, and right rear doors are closed, their corresponding door lock ajar switches opens the corresponding door ajar input circuit. The BCM then opens courtesy lamp low control circuit when any one of the door ajar input circuits is open.

The BCM powers the interior lights through the protected battery positive voltage courtesy lamps supply circuit. The BCM controls the power supplied to the protected battery positive voltage courtesy lamp supply circuit for inadvertent load (battery rundown) protection. The BCM also opens the courtesy lamps supply voltage circuit when the inadvertent battery power rundown protection is active.

Conditions for Setting the DTC

The BCM detects a short to battery positive voltage in courtesy lamps low control circuit.

Action Taken When the DTC Sets
    • The BCM sets the diagnostic trouble code (DTC) 3.
    • The interior courtesy lamps do not illuminate.

Conditions for Clearing the MIL/DTC
    • A short to battery positive voltage in the courtesy lamps low control circuit is no longer present between the BCM and any of the courtesy lamps.
    • After the repairs are completed, clear the DTC. Refer to On-Board Diagnostic Features .

Diagnostic Aids

Inspect for a short to battery positive voltage in the courtesy lamps low control circuit.

Interior Lighting Modes

Perform the following procedure in order to change the interior lighting mode:

  1. Turn off the instrument panel dimmer switch.
  2. Turn the ignition switch to the OFF position.
  3. Remove the MALL PGM fuse.
  4. Turn the ignition switch to the ACC position.

The BCM sounds the chime a number of times equivalent to the BCM type installed on the vehicle. At this time the BCM has entered the feature customizing mode. In order to change the interior lighting, cycle the IP dimmer switch from the OFF position to the DOME position and then back to the OFF position. The BCM sounds a chime a number of times equal to the lighting mode.

The lighting modes are as follows:

    • Mode 1 - Exit illumination and delayed illumination are disabled.
    • Mode 2 - Delay illumination is enabled.
    • Mode 3 - Exit illumination is enabled.
    • Mode 4 - Exit illumination and delayed illumination are enabled.

Test Description

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

  1. Always perform the lighting diagnostic system check before attempting to diagnose DTC 3.

    2.

  2. Tests for a short to voltage in the courtesy lamps low control circuit.

Courtesy Lights Ground Control Circuit Shorted to Battery Positive Voltage

Step

Action

Value(s)

Yes

No

Schematic Reference: Interior Lights Schematics

Connector End View Reference: Power and Grounding Connector End Views in Wiring Systems

1

Was the BCM Diagnostic System check performed?

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Go to Step 2

Go to Diagnostic System Check - Body Control System in Body Control Systems

2

Perform the BCM Input/Output test. Refer to Diagnostic Starting Point - Body Control System in Body Control System.

Do all lights connected to courtesy lamps low control circuit turn off when the BCM Input/Output performs test 3?

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

Go to Step 3

3
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the body control module (BCM) connector C1
  3. Turn the ignition switch to the RUN position.
  4. Measure the voltage of the courtesy lamps low control circuit between the BCM harness connector C1 and ground.

Is the voltage within the specified range?

Less than 2 V

Go to Step 5

Go to Step 4

4

Repair the short to battery positive voltage in courtesy lamps low control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

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Go to Step 6

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5

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

Did you complete the replacement?

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Go to Step 6

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6
  1. Turn the ignition switch to the OFF position.
  2. Reinstall connectors/components removed.
  3. Remove the MALL PGM Fuse.
  4. Turn the ignition switch to the ACC position. (The BCM sounds the chime a number of times equivalent to the BCM type installed on the vehicle).
  5. Within one second, turn the ignition switch from the ACC position, to the OFF position, then back to the ACC position. (The BCM sounds any DTCs stored).

Are there any BCM DTCs present?

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Go to Step 2

System OK