GM Service Manual Online
For 1990-2009 cars only
  1. Perform the Diagnostic System Check - Vehicle before using the Symptom Tables in order to verify that all of the following are true:
  2. • There are no DTCs set.
    • The control modules can communicate via the serial data link.
  3. Review the system operation in order to familiarize yourself with the system functions. Refer to the following:
  4. •  Exterior Lighting Systems Description and Operation
    •  Interior Lighting Systems Description and Operation

Visual/Physical Inspection

    • Inspect for aftermarket devices which could affect the operation of the Lighting System. Refer to Checking Aftermarket Accessories .
    • Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

    •  Backup Lamps Always On
    •  Backup Lamps Inoperative
    •  Cargo Lamp Always On
    •  Cargo Lamp Inoperative
    •  Clearance Lamps Inoperative
    •  Courtesy Lamps Always On
    •  Courtesy Lamps Inoperative
    •  Daytime Running Lamps (DRL) Always On
    •  Daytime Running Lamps (DRL) Defeat Inoperative
    •  Daytime Running Lamps (DRL) Inoperative
    •  Exterior Courtesy Lamps Always On
    •  Exterior Courtesy Lamps Inoperative
    •  Fog Lamp Indicator Inoperative
    •  Fog Lamps Always On
    •  Fog Lamps Inoperative
    •  Hazard Lamps Always On
    •  Hazard Lamps Inoperative
    •  Headlamp Low or High Beams Always On
    •  Headlamps Inoperative - High Beams
    •  Headlamps Inoperative - Low Beams
    •  Low and High Beams Headlamps Inoperative
    •  Headlamps Flash to Pass Inoperative
    •  High Beam Indicator Always On
    •  High Beam Indicator Inoperative
    •  Interior Backlighting Does Not Dim
    •  Interior Backlighting Inoperative
    •  Park, License, and Tail Lamps Always On
    •  Park, License, and Tail Lamps Inoperative
    •  Reading Lamp Inoperative
    •  Roof Beacon Lamp Always On
    •  Roof Beacon Lamp Inoperative
    •  Stop Lamps Always On
    •  Stop Lamps Inoperative
    •  Turn Signal Lamps and/or Indicators Always On or Flashing
    •  Turn Signal Lamps and/or Indicators Inoperative
    •  Vanity Mirror Lamp Inoperative

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

    •  Blackout Headlamp Inoperative
    •  Blackout Headlamp Always On
    •  Headlamps Operate in Blackout Mode
    •  Backup Lamps Inoperative
    •  Voltmeter Gage Lamp Inoperative
    •  Blackout Marker Lamps Inoperative
    •  Blackout Marker Lamps Always On
    •  Daytime Running Lamps (DRL) Operate in Blackout Mode
    •  Backup Lamps Operate in Blackout Mode
    •  Park Lamps Operate in Blackout Mode
    •  Courtesy Lamps Operate in Blackout Mode
    •  Turn Signals Operate in Blackout Mode
    •  High Beam Headlamps Operate in Blackout Mode
    •  Low Beam Headlamps Operate in Blackout Mode
    •  Backup Alarm Always On
    •  Backup Alarm Inoperative