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Home › Chevrolet › 2012 › Volt › Repair and Diagnosis › Body & Frame › Fixed And MOVEABLE Windows › Diagnostic Information and Procedures › Rear Window Defogger Malfunction › Circuit/System Verification

Circuit/System Verification

  1. Vehicle ON.
  2. Verify the scan tool Rear Defogger Switch parameter changes between On and Off when pressing the rear window defogger switch.
    • If the parameter does not change between On and Off 

      Replace the A20 Radio/HVAC controls.

    • If the parameter changes between On and Off 
  3. Verify the rear defogger indicator turns ON and OFF when pressing the rear window defogger switch.
    • If the rear defogger indicator does not turn ON and OFF 

      Replace the A20 Radio/HVAC controls.

    • If the rear defogger indicator turns ON and OFF 
  4. Verify the upper rear defogger grid and the lower rear defogger grid turns ON and OFF when commanding the rear window defogger ON and OFF with a scan tool.
    • If only the upper rear window defogger grid does not turn ON and OFF 

      Refer to Circuit/System Testing - Upper Defogger Grid Inoperative

    • If only the lower rear window defogger grid does not turn ON and OFF 

      Refer to Circuit/System Testing - Lower Defogger Grid Inoperative

    • If both upper and lower rear window defogger grids do not turn ON and OFF 

      Refer to Circuit/System Testing - Rear Window Defogger System Inoperative

    • If both the upper and lower rear window defogger grids turns ON and OFF 
  5. All OK.
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