GM Service Manual Online
For 1990-2009 cars only
  1. Perform the Diagnostic System Check - Vehicle in Vehicle DTC Information, 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 in Wiring Systems.
    • 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 in Wiring Systems.

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
    •  Courtesy Lamps Always On
    •  Courtesy Lamps Always On
    •  Courtesy Lamps Inoperative
    •  Daytime Running Lamps (DRL) Always On
    •  Daytime Running Lamps (DRL) 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
    •  Headlamps Flash to Pass Inoperative
    •  High Beam Indicator Always On
    •  High Beam Indicator Inoperative
    •  Interior Backlighting Does Not Dim
    •  Interior Backlighting Inoperative
    •  Instrument Panel Compartment Lamp Inoperative
    •  Instrument Panel Compartment Lamp Always On
    •  License Lamps Inoperative
    •  Marker Lamps Inoperative
    •  Park Lamps Inoperative
    •  Stop Lamps Always On
    •  Stop Lamps Inoperative
    •  Tail Lamps Inoperative
    •  Tail, Marker, and License Lamps Always On
    •  Tail, Marker, and License Lamps Inoperative
    •  Turn Signal Lamps and/or Indicators Always On or Flashing
    •  Turn Signal Lamps and/or Indicators Inoperative
    •  Vanity Mirror Lamp Inoperative