Symptoms - Lighting Systems. GMC Truck Savana 2004

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2004 🢒 Savana 🢒 Body 🢒 Lighting Systems 🢒 Symptoms - Lighting Systems

Perform the Diagnostic System Check - Lighting Systems before using the Symptom Tables in order to verify that all of the following are true:

•	There are no DTCs set.

•	The control modules can communicate via the serial data link.

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

•	Exterior Lighting Systems Description and Operation

•	Interior Lighting Systems Description and Operation

•	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.

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

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 Inoperative

•	Daytime Running Lamps (DRL) Inoperative

•	Dome Lamps Always On

•	Dome Lamps Inoperative

•	Hazard Lamps Always On

•	Hazard Lamps Inoperative

•	Headlamp Low or High Beams Always On

•	Headlamps Inoperative - High Beams

•	Headlamps Inoperative - Low Beams

•	Low and High Beams Headlamps Inoperative

•	Headlamps Flash to Pass Inoperative

•	High Beam Indicator Always On

•	High Beam Indicator Inoperative

•	Interior Backlighting Does Not Dim

•	Interior Backlighting Inoperative

•	Park, License, and Tail Lamps Always On

•	Park, License, and Tail Lamps Inoperative

•	Reading Lamp Inoperative

•	Stop Lamps Always On

•	Stop Lamps Inoperative

•	Turn Signal Lamps and/or Indicators Always On or Flashing

•	Turn Signal Lamps and/or Indicators Inoperative

•	Underhood Lamp Inoperative

•	Vanity Mirror Lamp Inoperative