GM Service Manual Online
For 1990-2009 cars only

Important: The following steps must be completed before using the symptom tables.

  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 and circuit descriptions that apply to the customer complaint in order to familiarize yourself with the system functions. Refer to the following list:
  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
    •  Clearance Lamps Inoperative
    •  Cornering Lamps Always On
    •  Cornering Lamps Inoperative
    •  Courtesy Lamps Always On
    •  Courtesy Lamps Inoperative
    •  Daytime Running Lamps (DRL) Defeat Inoperative
    •  Daytime Running Lamps (DRL) Inoperative
    •  Daytime Running Lamps (DRL) On with Park Brake Applied
    •  Fog Lamp Indicator Inoperative
    •  Fog Lamps Always On
    •  Fog Lamps Inoperative
    •  Rear Fog Lamps Always On
    •  Rear Fog Lamps Inoperative
    •  Hazard Lamps Always On
    •  Hazard Lamps Inoperative
    •  Headlamp Switch On Indicator Always On
    •  Headlamp Switch On Indicator Inoperative
    •  Headlamp Low or High Beams Always On
    •  Headlamps Inoperative - High Beams
    •  Headlamps Inoperative - Low Beams
    •  Headlamps Flash to Pass Inoperative
    •  Headlight Leveling Inoperative
    •  High Beam Indicator Always On
    •  High Beam Indicator Inoperative
    •  Interior Backlighting Does Not Dim
    •  Interior Backlighting Inoperative
    •  License Lamps Inoperative
    •  Marker Lamps Inoperative
    •  Memory/Heated Seat Switch Backlighting 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