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 602 (FIXED AND MOVEABLE WINDOWS SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESREAR WINDOW DEFOGGER 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 is about a different car, the 2010 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition ON, observe the scan tool Rear Defog Switch parameter while pressing the rear window defogger switch. The parameter should change between Inactive and Active.
- If the value does not change between the commanded states, replace the HVAC control module.
- Observe the operation of the rear window defogger indicator while pressing the rear window defogger switch. The indicator should turn ON or OFF each time the rear window defogger switch is pressed.
- If the indicator does not turn ON or OFF with each switch press, replace the HVAC control module.
- Command the Rear Defog Relay ON and OFF with a scan tool. The rear window defogger should turn ON and OFF when changing between the commanded states.
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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.