GM Service Manual Online
For 1990-2009 cars only

Circuit Description

When the headlamp switch is turned to the PARK or HEAD position, the body control module (BCM) applies battery positive voltage to the I/P courtesy lamps. When a door is opened, the door latch assembly applies a ground to the BCM. The BCM supplies battery positive voltage to the courtesy lamp supply voltage circuit and applies a ground to the courtesy lamps control circuit.

Conditions for Running the DTC

Voltage supplied to the BCM is in the normal operating range, approximately 9-14 volts.

Conditions for Setting the DTC

    • The BCM detects a low when a high is expected in either the instrument panel lamps supply voltage circuit or the courtesy lamp supply voltage circuit.
    • The condition above must be present for more then 0.1 seconds

Action Taken When the DTC Sets

    • The BCM L Fuse opens.
    • The courtesy lamps are inoperative.
    • The I/P courtesy lamps are inoperative.
    • The BCM stores DTC B1482 in memory.
    • The BCM store DTC B2627 in memory.

Conditions for Clearing the MIL/DTC

    • A current DTC B1482 and B2627 clears when the BCM no longer detects a short to ground in the instrument panel lamps supply voltage circuit or the courtesy lamps supply voltage circuit.
    • A history DTC B1482 and B2627 clears after 100 consecutive ignition cycles.

Diagnostic Aids

    • The BCM L Fuse opens when there is a short to ground in either the instrument panel lamps supply voltage circuit or the courtesy lamps supply voltage circuit and must be replaced before doing any diagnostics.
    • If the DTC B1482 or B2627 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • The following conditions may cause an intermittent malfunction to occur:
       - An intermittent short to ground in the instrument panel lamps supply voltage circuit or the courtesy lamps supply voltage circuit.
       - The BCM is intermittently shorted to ground.

Step

Action

Yes

No

Schematic Reference: Interior Lights Dimming Schematics and Interior Lights Schematics

Connector End View Reference: Master Electrical Component List

1

Did you perform the Lighting Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn the ignition to the OFF position.
  2. Turn the headlamp switch to the OFF position.
  3. Open the passenger door.
  4. Replace the BCM L fuse.

Does the BCM L fuse open?

Go to Step 4

Go to Step 3

3

  1. Turn the ignition to the RUN position.
  2. Turn the headlamp switch to the park position.
  3. Observe the I/P courtesy lamps.

Are lamps illuminated?

Go to Diagnostic Aids

Go to Step 5

4

Important: A short to ground on either the courtesy lamp supply voltage circuit or the instrument panel lamps supply voltage circuit will cause the BCM L fuse to open. You must replace this fuse as needed to ensure proper diagnosis.

Test the courtesy lamp supply voltage circuit a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 6

5

Important: A short to ground on either the courtesy lamp supply voltage circuit or the instrument panel lamps supply voltage circuit will cause the BCM L fuse to open. You must replace this fuse as needed to ensure proper diagnosis.

Test the instrument panel lamps supply voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 7

Go to Step 6

6

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

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

Did you complete the replacement?

Go to Step 7

--

7

  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