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Circuit/System Testing

  1. Vehicle OFF and all vehicle systems OFF, disconnect the KR5 Rear Defogger Relay. 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 40 and ground.
    • If 10 Ω or greater 
    1. Vehicle 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. Vehicle in Service Mode.
  4. Verify a test lamp illuminates between the B+ circuit terminal 43 and ground.
    • If the test lamp does not illuminate 
    • Replace the X53A Fuse Block-Rear Body
    • If the test lamp illuminates 
  5. Connect a test lamp between the control circuit terminal 41 and the ground circuit terminal 40.
  6. Verify the test lamp turns ON and OFF pressing the rear window defogger switch.
    • If the test lamp is always OFF 
    1. Vehicle OFF, remove the test lamp, disconnect the harness connector at the K33 HVAC Control Module.
    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, replace the K33 HVAC Control Module.
    • If the test lamp is always ON 
    1. Vehicle OFF, remove the test lamp, disconnect the harness connector at the K33 HVAC Control Module, Vehicle in Service Mode.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module.
    • If the test lamp turns ON and OFF 
  7. Verify that a test lamp does not illuminate between the control circuit terminal 42 and ground.
    • If the test lamp illuminates 

      Repair the short to voltage on the control circuit

    • If the test lamp does not illuminate 
  8. Vehicle OFF and all vehicle systems OFF, disconnect the X2 harness connector at the E18 Rear Defogger Grid. It may take up to 2 minutes for all vehicle systems to power down.
  9. Test for less than 10 Ω between the ground circuit terminal A and ground.
    • If 10 Ω or greater 
    1. Vehicle 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 
  10. Connect the X2 harness connector at the E18 Rear Defogger Grid.
  11. Vehicle in Service Mode, connect a 40 A fused jumper wire between the B+ circuit terminal 43 and the control circuit terminal 42.
  12. Verify the E18 Rear Defogger Grid is activated.
    • If the E18 Rear Defogger Grid does not activate 
    1. Vehicle OFF, remove the jumper wire, disconnect the X1 harness connector at the E18 Rear Defogger Grid.
    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, replace the E18 Rear Defogger Grid.
    • If the E18 Rear Defogger Grid activates 
  13. Test or replace the KR5 Rear Defogger Relay.
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