GM Service Manual Online
For 1990-2009 cars only

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

  1. Perform the Diagnostic System Check 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.

Visual/Physical Inspection

Several of the symptom procedures ask for a careful visual/physical check. This step is extremely important it could lead to correcting a problem without further checks and can save valuable time. These checks include the following:

    • Inspect for aftermarket devices which could affect the operation of the lighting system.
    • Inspect the easily accessible or visible system components and harness connectors for obvious damage or conditions which could cause the symptom.
    • If only one lamp is inoperative, inspect and repair a poor connection or an open in the power feed or ground circuit before replacing the light bulb.

Intermittent

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

Symptom List

Refer to the following list in order to diagnose the symptom:

    •  Backup Lamps Always On
    •  Backup Lamps Inoperative
    •  Courtesy Lamps Always On
    •  Courtesy Lamps Inoperative
    •  Daytime Running Lamps (DRL) Inoperative
    •  Dome Lamps Inoperative
    •  Fog Lamps Always On
    •  Fog Lamps Inoperative
    •  Hazard Lamps Inoperative
    •  Headlamps Inoperative - High Beams
    •  Headlamps Inoperative - Low Beams
    •  Low and High Beams Headlamps Inoperative
    •  Headlamps Flash to Pass Inoperative
    •  Illuminated Entry Lamps Inoperative
    •  Stop Lamps Inoperative
    •  Turn Signal Lamps and/or Indicators Inoperative