GM Service Manual Online
For 1990-2009 cars only

Important: The following steps must be completed before doing the Symptom tables.

  1. Perform the Diagnostic System Check - Vehicle .
  2. • No DTCs are 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 Exterior Lighting Systems Description and Operation or 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:

    •  Automatic Lamp Control Inoperative
    •  Backup Lamps Inoperative
    •  Courtesy Lamps Always On
    •  Courtesy Lamps Inoperative
    •  Daytime Running Lamps (DRL) Inoperative
    •  Hazard Lamps Always On
    •  Hazard Lamps Inoperative
    •  High Mount Stop Lamp Inoperative
    •  Headlamp Low or High Beams Always On
    •  Headlamps Inoperative - High Beams
    •  Headlamps Inoperative - Low Beams
    •  Headlamps Flash to Pass Inoperative
    •  Illuminated Entry Lamps Inoperative
    •  Interior Backlighting Does Not Dim
    •  Interior Backlighting Inoperative
    •  Park, License, and Tail Lamps Always On
    •  Park, License, and Tail Lamps Inoperative
    •  Reading Lamp Always On
    •  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 Always On
    •  Vanity Mirror Lamp Inoperative