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Home › Buick › 2021 › Envision Essence, AWD › Repair and Diagnosis › Body & Frame › Fixed And MOVEABLE Windows › Diagnostic Information and Procedures › DTC B1066 › Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF and all vehicle systems OFF, disconnect the KR5 Rear Window Defogger Relay
  2. Verify a test lamp illuminates between ground circuit terminal 86 and B+.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on circuit 1150 or the ground connection.
    • Go to next step: If the test lamp illuminates 
  3. Ignition - On/Vehicle - In Service Mode
  4. Connect a test lamp between the test points: Control circuit terminal 85 & ground
  5. Operate the component: S59 Rear Defogger Switch - Pressed

    Verify the test lamp turns ON and OFF

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module
    2. Test for infinite resistance between the control 193 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 193 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.
    2. Test for less than 1 V between the control 193 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
    • Go to next step: If the test lamp turns ON and OFF 
  6. Replace the KR5 Rear Window Defogger Relay.
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