LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2021 >> Tahoe SSV >> 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 Window Defogger Grid. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between the E18 Rear Window Defogger Grid 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.
    • Go to next step: If less than 10 Ω 
  3. Connect a test lamp between the control circuit terminal 1 X1 and ground, ignition ON.
  4. Verify the test lamp does not turn ON and OFF when pressing the appropriate switch on the A26 Heater and Air Conditioning User Interface Control - Front
    • If the test lamp turns ON and OFF 

      Test or replace the E18 Rear Window Defogger Grid.

    • Go to next step: If the test lamp does not turn ON and OFF 
  5. Ignition OFF, connect the X1 and X2 harness connectors at the E18 Rear Window Defogger Grid. Disconnect the X1 and X2 harness connectors at the X53A Body Wiring Harness Junction Block - Rear, ignition ON.
  6. Verify the E18 Rear Window Defogger Grid is not activated.
    • If the E18 Rear Window Defogger Grid is activated 
    1. Ignition OFF, disconnect the X1 harness connector at the E18 Rear Window Defogger Grid, ignition ON.
    2. Test for less than 1 V between the E18 Rear Window Defogger Grid control circuit terminal 1 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 Window Defogger Grid.
    • Go to next step: If the E18 Rear Window Defogger Grid is not activated 
  7. Connect a 40 A fused jumper wire between the control circuit terminal 17 X2 and B+.
  8. Verify the E18 Rear Window Defogger Grid activates.
    • If the E18 Rear Window Defogger Grid does not activate 
    1. Ignition OFF, remove the jumper wire, disconnect the X1 harness connector at the E18 Rear Window Defogger Grid.
    2. Test for infinite resistance between the E18 Rear Window Defogger Grid control circuit terminal 1 and ground.
      • If less than Infinite resistance, repair the short to ground on the circuit.
      • Go to next step: 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, all OK.
    • Go to next step: If the E18 Rear Window Defogger Grid activates 
  9. Ignition OFF and all vehicle systems OFF. It may take up to 2 min for all vehicle systems to power down.
  10. Test for less than 10 Ω between the X53A Body Wiring Harness Junction Block - Rear ground circuit terminal 5 X1 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.
    • Go to next step: If less than 10 Ω 
  11. Connect the X1 and X2 harness connectors at the X53A Body Wiring Harness Junction Block - Rear. Disconnect the X5 harness connector at the K9 Body Control Module, ignition ON.
  12. Verify the E18 Rear Window Defogger Grid is not activated.
    • If the E18 Rear Window Defogger Grid is activated 
    1. Ignition OFF, disconnect the X2 harness connector at the X53A Body Wiring Harness Junction Block - Rear, ignition ON.
    2. Test for less than 1 V between the K9 Body Control Module control circuit terminal 22 X5 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, test or replace the X53A Body Wiring Harness Junction Block - Rear.
    • Go to next step: If the E18 Rear Window Defogger Grid is not activated 
  13. Connect a 3 A fused jumper wire between the control circuit terminal 22 X5 and B+.
  14. Verify the E18 Rear Window Defogger Grid activates.
    • If the E18 Rear Window Defogger Grid does not activate 
    1. Ignition OFF, remove the jumper wire, disconnect the X2 harness connector at the X53A Body Wiring Harness Junction Block - Rear.
    2. Test for infinite resistance between the K9 Body Control Module control circuit terminal 22 X5 and ground.
      • If less than Infinite resistance, repair the short to ground on the circuit.
      • Go to next step: 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 X53A Body Wiring Harness Junction Block - Rear.
    • Go to next step: If the E18 Rear Window Defogger Grid activates 
  15. Replace the K9 Body Control Module.
scientia non olet · About LEMON Manuals