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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 191 (Fixed & MOVEABLE Window Systems) >> Diagnostic Information & Procedures >> Rear Window Defogger Malfunction >> Circuit/System Verification

Circuit/System Verification

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  1. Ignition ON, observe the scan tool Rear Defrost State parameter while pressing the rear window defogger switch. The parameter should change between On and Off.
    • If the parameter does not change between the commanded states, replace the HVAC control module.
  2. 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.
  3. Command the Rear Defog Request 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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