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Home >> Buick >> 2013 >> Encore Base, AWD >> 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

  1. Ignition OFF, and all vehicle systems OFF. Disconnect the X1 and X2 harness connectors at the E18 Rear Defogger Grid. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 1 X2 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • 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 
  3. Connect a test lamp between the control circuit terminal 1 X1 and ground, Engine Running.
  4. Verify the test lamp does not turn ON and OFF pressing the rear window defogger switch.
    • If the test lamp turns ON and OFF 

      Test or replace the E18 Rear Defogger Grid.

    • If the test lamp does not turn ON and OFF 
  5. Ignition OFF, connect the X1 and X2 harness connectors at the E18 Rear Defogger Grid. Disconnect the X2 harness connector at the X50A Fuse Block-Underhood. It may take up to 2 minutes for all vehicle systems to power down.
  6. Test for less than 10 Ω between the ground circuit terminal C5 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • 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 
  7. Ignition ON
  8. Verify the E18 Rear Defogger Grid is not activated.
    • If the E18 Rear Defogger Grid is activated 
    1. Ignition OFF, disconnect the X1 harness connector at the E18 Rear Defogger Grid, ignition ON.
    2. Test for less than 1 V between the X50A Fuse Block-Underhood control circuit terminal A3 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, test or replace the E18 Rear Defogger Grid.
    • If the E18 Rear Defogger Grid is not activated 
  9. Connect a 30A fused jumper wire between the control circuit terminal A3 and B+.
  10. Verify the E18 Rear Defogger Grid activates.
    • If the E18 Rear Defogger Grid does not activate 
    1. Ignition OFF, remove the jumper wire, disconnect the X1 harness connector at the E18 Rear Defogger Grid, ignition ON.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than Infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, test or replace the E18 Rear Defogger Grid.
    • If the E18 Rear Defogger Grid activates 
  11. Ignition OFF, connect the X2 harness connector at the X50A Fuse Block-Underhood. Disconnect the X2 harness connector at the K33 HVAC Control Module, ignition ON.
  12. Verify the E18 Rear Defogger Grid is not activated.
    • If the E18 Rear Defogger Grid is activated 
    1. Ignition OFF, disconnect the X2 harness connector at the X50A Fuse Block-Underhood.
    2. Test for less than 1 V between the K33 HVAC Control Module control circuit terminal 19 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the X50A Fuse Block-Underhood.
    • If the E18 Rear Defogger Grid is not activated 
  13. Connect a 3 A fused jumper wire between the control circuit terminal 19 and B+.
  14. Verify the E18 Rear Defogger Grid activates.
    • If the E18 Rear Defogger Grid does not activate 
    1. Ignition OFF, remove the jumper wire, disconnect the X2 harness connector at the X50A Fuse Block-Underhood, ignition ON.
    2. Test for Test for infinite resistance between the K33 HVAC Control Module control circuit terminal 19 and ground.
      • If less than Infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the X50A Fuse Block-Underhood.
    • If the E18 Rear Defogger Grid activates 
  15. Replace the K33 HVAC Control Module.
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