Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G3500, VAN PASSENGER EXTENDEDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 279 (LIGHTING SYSTEMS)DIAGNOSTIC INFORMATION & PROCEDURESCOURTESY LAMPS MALFUNCTIONCIRCUIT/SYSTEM VERIFICATION
2008 Chevrolet Chevy Express G3500, Van Passenger Extended
Circuit/System Verification
2008 Chevrolet Chevy Express G3500, Van Passenger ExtendedSECTION Circuit/System Verification
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition ON, command the Courtesy Lamps output control ON and OFF with the scan tool. The interior courtesy lamps should turn ON and OFF.
- If one or more of the courtesy lamps are always ON or always OFF refer to the Courtesy Lamp Malfunction .
- Observe the scan tool Driver Door Switch, Driver Door Open Sw. parameter while opening and closing the driver door. The reading should change between Active and Inactive.
- If the Driver Door Open Sw. parameter does not change between Active and Inactive, refer to Door Open Switch Malfunction-Front .
- Observe the scan tool Passenger Door Switch, Passenger Door Open Sw. parameter while opening and closing the front passenger door. The reading should change between Active and Inactive.
- If the Passenger Door Open Sw. parameter does not change between Active and Inactive, refer to Door Open Switch Malfunction-Front .
- Observe the scan tool BCM Ctsy. Lamp Actv. Reason parameter while opening and closing each rear doors one at a time. The reading should change between Door Open and Door Closed
- If the Ctsy. Lamp Actv. Reason parameter does not change between Door Open and Door Closed, refer to Door Open Switch Malfunction-Rear .
- Ignition ON and all doors closed, observe the scan tool BCM Ctsy. Lamp Actv. Reason parameter while turning the dome lamp switch ON and OFF. The reading should change between Off and Manual.
- If the Ctsy. Lamp Actv. Reason parameter does not change between Off and Manual, refer to Dome/Interior Lamp Switch Malfunction .
- Ignition ON and all doors closed, observe the scan tool BCM Ctsy. Lamp Actv. Reason parameter while turning the interior lamp defeat switch ON and OFF. The reading should change between Off and Manual Defeat.
- If the Ctsy. Lamp Actv. Reason parameter does not change between Off and Manual, refer to Dome/Interior Lamp Switch Malfunction .
- Ignition ON, command the Puddle/Courtesy Lamp ON and OFF with a scan tool. Verify the exterior illumination lamps turn ON and OFF.
- If the exterior illumination lamps do not change between ON and OFF, refer to Exterior Illumination Lamps Malfunction Test .
- Ignition ON, turn the reading lamps ON and OFF. The reading lamps should turn ON and OFF.
- If the reading lamps do not change between ON and OFF, refer to Reading Lamps Malfunction Test .
- Ignition On, fold down the sun visors and verify the vanity lamps illuminate.
- If the vanity lamps do not change between ON and OFF, refer to Vanity Mirrors Malfunction Test .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.