GM Service Manual Online
For 1990-2009 cars only

Important: Review the system operation in order to familiarize yourself with the system functions. Refer to :

    •  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
    •  Daytime Running Lamps (DRL) Always On
    •  Daytime Running Lamps (DRL) Indicator Inoperative
    •  Daytime Running Lamps (DRL) Inoperative
    •  Daytime Running Lamps (DRL) On with Park Brake Applied
    •  Dome Lamps Always On
    •  Dome Lamps Inoperative
    •  Hazard Lamps Inoperative
    •  Headlamp Low or High Beams Always On
    •  Headlamps Inoperative - Low Beams
    •  Headlamps Inoperative - High Beams
    •  Low and High Beams Headlamps Inoperative
    •  Headlamps Flash to Pass Inoperative
    •  High Beam Indicator Inoperative
    •  Interior Backlighting Does Not Dim
    •  Interior Backlighting Inoperative
    •  Marker Lamps Always On
    •  Marker Lamps Inoperative
    •  Marker Lamps Inoperative - Output at Trailer/Upfitter Connector
    •  Park Lamps Always On
    •  Park Lamps Inoperative
    •  Park Lamps Inoperative - Output at Trailer/Upfitter Connector
    •  Stop Lamps Always On
    •  Stop Lamps Inoperative
    •  Stop Lamps Inoperative - Output at Trailer/Upfitter Connector
    •  Turn Signal Lamps and/or Indicators Always On or Flashing
    •  Turn Signal Lamps and/or Indicators Inoperative
    •  Turn Signal Lamps Inoperative - Output at Trailer/Upfitter Connector