GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

DEFINITION: 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 in the OFF position.

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. Make sure the I/P dimmer switch is off.
  2. Turn the ignition switch on.
  3. Lower the driver's window (to prevent lockout).
  4. Close all vehicle doors.

Are the courtesy lamps off?

--

Go to Step 3

Go to Step 7

3

  1. Connect a scan tool to the Data Link Connector (DLC).
  2. Using scan tool, monitor the park lamp off input.
  3. While observing the scan tool, turn the headlamp switch from the OFF to the HEAD position, back to the OFF position.

Does the scan tool indicate that the park lamp off input is on while the headlamp switch was in the OFF position?

--

Go to Step 8

Go to Step 4

4

  1. Turn the headlamp switch to the OFF position.
  2. Using a test light, connect between the BCM connector C1 terminal C2 and ground.

Is the test light on?

--

Go to Step 8

Go to Step 5

5

  1. Disconnect C201.
  2. Using a test light, connect between C201 terminal Z (male side of connector) and ground.

Is the test light on?

--

Go to Step 6

Go to Step 9

6

  1. Disconnect the BCM connector C1.
  2. Using a DMM, measure the resistance between the BCM harness connector C1 terminal C2 and C201 terminal T (male side of connector) and ground.

Is the resistance within the specified range?

Less than 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 Interior Lamps System Check for diagnosis and repair of the interior lights door lock ajar input.

Is the action complete?

--

Go to Step 12

 

8

  1. Replace the BCM. Refer to Body Control Module Replacement in Body Control System for service procedures.
  2. After BCM replacement, 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 poor connection or open in circuit 1340.

Is the repair complete?

--

Go to Step 12

--

10

    • Inspect C201 terminals T and Z for a poor connection.
    • If the connection is OK, then replace the headlamp switch. Refer to Turn Signal and Multifunction Switch Assembly - Disassemble - Off Vehicle in Steering Wheel and Column - Tilt for service procedures.

Is the repair complete?

--

Go to Step 12

--

11

Repair poor connection or open in circuit 1872.

Is the repair complete?

--

Go to Step 12

--

12

  1. Turn the ignition switch off.
  2. Reinstall the connectors/components removed.
  3. Check 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

System OK