Symptoms - Lighting Systems. GMC Truck GMC C-Series Medium Duty Truck B7 2001

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2001 🢒 GMC C-Series Medium Duty Truck B7 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Symptoms - Lighting Systems

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

•	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

•	Daytime Running Lamps (DRL) Indicator Inoperative

•	Daytime Running Lamps (DRL) Inoperative

•	Daytime Running Lamps (DRL) On with Park Brake Applied

•	Hazard Lamps Inoperative

•	Headlamps Inoperative - Low Beams

•	Headlamps Inoperative - High Beams

•	Low and High Beams Headlamps Inoperative

•	High Beam Indicator Inoperative

•	Interior Backlighting Does Not Dim

•	Interior Backlighting Inoperative

•	Park Lamps Always On

•	Park Lamps Inoperative

•	Park Lamps Inoperative - Output at Trailer/Upfitter Connector

•	Stop Lamps Always On

•	Stop Lamps Inoperative

•	Turn Signal Lamps and/or Indicators Inoperative

•	Turn Signal Lamps Inoperative - Output at Trailer/Upfitter Connector