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Home >> GMC >> 2018 >> Canyon SL >> Repair and Diagnosis >> Body & Frame >> Fixed And MOVEABLE Windows System >> Diagnostic Information And Procedures >> Rear Window Defogger Malfunction >> Circuit/System Verification
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Circuit/System Verification

  1. Engine running.
  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 K33 HVAC Control Module.

    • Go to next step: If the parameter changes between On and Off 
  3. Verify the E18L Rear Defogger Grid - Left, E18C Rear Defogger Grid - Middle, E18R Rear Defogger Grid - Right turns ON and OFF when pressing the rear window defogger switch.
    • If the E18L Rear Defogger Grid - Left and E18R Rear Defogger Grid - Right does not turn ON and OFF 

      Refer to Circuit/System Testing below

    • If the E18C Rear Defogger Grid - Middle does not turn ON 

      Test or replace the E18C Rear Defogger Grid - Middle

    • Go to next step: If the E18L Rear Defogger Grid - Left, E18C Rear Defogger Grid - Middle, E18R Rear Defogger Grid - Right turns ON and OFF 
  4. 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 K33 HVAC Control Module.

    • Go to next step: If the rear defogger indicator turns ON and OFF 
  5. All OK.
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