GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

The BCM sounds the headlamps on reminder when one or more of the following conditions are present:

    • The driver's door is closed.
    • The headlamp switch is OFF.

1

Was the BCM Diagnostic System Check performed?

--

Go to Step 2

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

2

  1. Ensure that the IP dimmer switch is off.
  2. Turn the ignition switch to the RUN position.
  3. Lower the driver's window in order to prevent lockout.
  4. Close all of the vehicle's doors.

Are the courtesy lights off?

--

Go to Step 3

Go to Step 7

3

  1. Connect a scan tool to the data link connector (DLC).
  2. Use the scan tool in order to monitor the park lamp off input.
  3. While observing the scan tool, turn the headlamp switch from OFF to HEAD and back to OFF.

Does the scan tool indicate that the park lamp off input is active with the headlamp switch off?

--

Go to Step 8

Go to Step 4

4

  1. Turn the headlamp switch OFF.
  2. Connect a test lamp.
  3. Backprobe between the BCM connector C1 terminal C2 and ground.

Does the test lamp light?

--

Go to Step 8

Go to Step 5

5

  1. Disconnect the headlamp switch electrical connector.
  2. Connect a test lamp.
  3. Backprobe between the headlamp switch harness connector terminal E and ground.

Does the test lamp light?

--

Go to Step 6

Go to Step 9

6

  1. Disconnect the BCM connector C1.
  2. Use a DMM in order to measure the resistance between the BCM harness connector C1 terminal C2 and the headlamp switch harness connector terminal F.

Is the resistance measured less than the specified value?

2ohms

Go to Step 10

Go to Step 11

7

The headlamps on reminder is on with the driver's door closed due to a malfunction between the BCM and the driver's door lock ajar switch. Refer to Diagnostic System Check - Lighting Systems in Lighting Systems for further diagnosis.

Is the action complete?

--

Go to Step 12

--

8

  1. Replace the BCM. Refer to Body Control Module Replacement in Body Control System.
  2. Perform the Setup New BCM procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Is the repair complete?

--

Go to Step 12

--

9

Repair a poor connection or an open in circuit 1340.

Is the repair complete?

--

Go to Step 12

--

10

  1. Inspect the headlamp switch connection terminals E and F for a poor connection.
  2. If the connection is OK, replace the headlamp switch assembly. Refer to Headlamp Switch Replacement in Lighting Systems.

Is the repair complete?

--

Go to Step 12

--

11

Repair a poor connection or an open in circuit 1872.

Is the repair complete?

--

Go to Step 12

--

12

  1. Turn the ignition switch to LOCK.
  2. Reconnect the connectors and reinstall the components that were removed.
  3. Inspect for BCM current DTCs. Refer to Diagnostic Trouble Code (DTC) Displaying in Body Control System.

Are there any BCM current DTCs present?

--

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

Go to Audible Warnings System Check