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Home >> GMC >> 2017 >> Acadia SL >> Repair and Diagnosis >> Body & Frame >> Windows >> Fixed And MOVEABLE Window System >> Diagnostic Information and Procedures >> Rear Window Defogger Malfunction >> Circuit/System Testing

Circuit/System Testing

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems » Off
  2. Disconnect the electrical connector:X1 & X2 E18 Rear Defogger Grid
  3. Test for less than 10 Ω between the test points:Ground circuit terminal 1X2 & Ground
    • If 10 Ω or greater 
    1. Ground Connection»Disconnect
    2. Test for less than 2 Ω between the test points:Ground circuit terminal 1X2@Component harness & Ground Connection
      • If 2 Ω or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  4. Verify the fuse is not open: F8RA Fuse
    • If the fuse is open 
    1. Replace the component:F8RA Fuse
    2. Verify the fuse does not open.
      • If the fuse opens » Test or replace the component:X53A Fuse Block - Rear Body
      • If the fuse does not open, go to the next step.
    • If the fuse is not open 
  5. Connect a test lamp between the test points:Control circuit terminal 1 X1 & Ground circuit terminal 1 X2
  6. Ignition » On / Vehicle » In Service Mode
  7. Operate the component:Rear Defogger Switch »Pressed

    Verify the test lamp does not turn On and Off.

    • If the test lamp turns On and Off 

      Test or replace the component:E18 Rear Defogger Grid

    • If the test lamp does not turn On and Off 
  8. Ignition/Vehicle » Off
  9. Connect the electrical connector:X1 & X2 E18 Rear Defogger Grid
  10. Disconnect the electrical connector:X1 X53A Fuse Block - Rear Body
  11. Ignition » On / Vehicle » In Service Mode
  12. Momentarily connect a 3 A fused jumper wire between the test points:Control circuit terminal 1 X1 B+

    Verify the component turns On and Off when connecting and disconnecting the jumper wire:E18 Rear Defogger Grid

    • If the component does not turn On and Off 
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector: X1 E18 Rear Defogger Grid
    3. Ignition » On / Vehicle » In Service Mode
    4. Test for less than 1 V between the test points:Control circuit terminal 1 X1@Component harness & Ground
      • If 1 V or greater » Repair the short to voltage on the circuit.
      • If less than 1 V
    5. Ignition/Vehicle » Off
    6. Test for infinite resistance between the test points:Control circuit terminal 1 X1 @Component harness & Ground
      • If less than infinite resistance » Repair the short to ground on the circuit.
      • If infinite resistance
    7. Test for less than 2 Ω between the test points:Control circuit terminal 1 X1 @Component harness & Control circuit terminal 1 X1 @Fuse Block Harness
      • If 2 Ω or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Test or replace the component:E18 Rear Defogger Grid
    • If the component turns On and Off 
  13. Ignition/Vehicle & All vehicle systems » Off
  14. Verify the fuse is not open:F8RA Fuse
    • If the fuse is open 

      Test or replace the component:X53A Fuse Block - Rear Body

    • If the fuse is not open 
  15. Test for less than 10 Ω between the test points:Ground circuit terminal 34 X2 & Ground
    • If 10 Ω or greater 
    1. Ground Connection»Disconnect
    2. Test for less than 2 Ω between the test points:Ground circuit terminal 34 X2 & Ground Connection
      • If 2 Ω ; or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  16. Connect the electrical connector:X53A Fuse Block - Rear Body
  17. Disconnect the electrical connector:X2K33 HVAC Control Module
  18. Ignition » On / Vehicle » In Service Mode
  19. Momentarily connect a 3 A fused jumper wire between the test points:Control circuit terminal 19 X2 & B+

    Verify the component turns On and Off when connecting and disconnecting the jumper wire:E18 Rear Defogger Grid

    • If the component does not turn On and Off 
    1. Ignition/Vehicle » Off & Remove » Jumper wire(s)
    2. Disconnect the electrical connector: X2 X53A Fuse Block - Rear Body
    3. Ignition » On / Vehicle » In Service Mode
    4. Test for less than 1 V between the test points:Control circuit terminal 19 X2 @Control module harness & Ground
      • If 1 V or greater » Repair the short to voltage on the circuit.
      • If less than 1 V
    5. Ignition/Vehicle » Off
    6. Test for infinite resistance between the test points:Control circuit terminal 19 X2 @Control module harness & Ground
      • If less than infinite resistance » Repair the short to ground on the circuit.
      • If infinite resistance
    7. Test for less than 2 Ω between the test points:Control circuit terminal 19 X2 @Control module harness & Terminal 40 X2 @Fuse Block Harness
      • If 2 Ω or greater » Repair the open/high resistance in the circuit.
      • If less than 2 Ω » Test or replace the component:X53A Fuse Block - Rear Body
    • If the component turns On and Off 
  20. Replace the component:K33 HVAC Control Module
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