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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 21 (Wiring Systems And Power Management - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Ignition Mode Switch Indicator Malfunction >> Circuit/System Testing

Circuit/System Testing

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Test - Run/Crank Mode Indicator Malfunction

  1. Ignition OFF, disconnect the connector at the S38 On/Off Vehicle Switch.
    2. NOTE:

    If the Amber Accessory Mode indicator functions this step does not need to be performed proceed to the next step.

  2. Verify a test lamp illuminates between ground terminal 3 and B+
    • If the test lamp does not illuminate 

      Repair the open/high resistance on circuit 1351 or ground connection.

    • Go to next step: If the test lamp illuminates 
  3. Connect the connector at the S38 Vehicle On/Off Switch.
  4. Connect a test lamp between control circuit terminal 1 and ground terminal 3 at the S38 Vehicle On/Off switch.
  5. Verify the test lamp turns On and Off while repeatedly cycling the ignition between Run and Off.
    • If the test lamp does not turn on and off 
    1. Test the control circuit 5719 for a short to ground.
      • If a short to ground is found repair the fault in the circuit
      • Go to next step: If a short to ground is not found
    2. Test the control circuit 5719 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open or high resistance is not found
    3. Ignition ON, disconnect connector at the S38 Vehicle On/Off Switch and connector X3 at the K9 Body Control Module.
    4. Test less than 1 V Between control circuit 5719 and ground.
      • If 1 V or greater

        Repair the short to voltage on circuit 5719.

      • Go to next step: If less than 1 V
    5. Replace the K9 Body Control Module.
    • Go to next step: If the Test lamp turns on and off 
  6. Replace the S38 Vehicle On/Off Switch.

Test - Accessory Mode Indicator Malfunction

  1. Ignition OFF, disconnect the connector at the S38 On/Off Vehicle Switch.
    2. NOTE:

    If the green Run/Propulsion Mode indicator functions this step does not need to be performed proceed to the next step.

  3. Verify a test lamp illuminates between the ground circuit terminal 3 and B+
    • If the test lamp does not illuminate 

      Repair the open/high resistance on circuit 1351 or ground connection.

    • Go to next step: If the test lamp illuminates 
  4. Connect the connector at the S38 Vehicle On/Off Switch.
  5. Connect a test lamp between control circuit terminal 2 and ground terminal 3 at the S38 Vehicle On/Off switch.
  6. Verify the test lamp turns On and Off while repeatedly cycling the ignition between Accessory and Off.
    • If the test lamp does not turn on and off 
    1. Test the control circuit 5720 for a short to ground.
      • If a short to ground is found repair the fault in the circuit
      • Go to next step: If a short to ground is not found
    2. Test the control circuit 5720 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found
    3. Ignition ON, disconnect connector at the S38 Vehicle On/Off Switch and connector X2 at the K9 Body Control Module.
    4. Test less than 1 V Between control circuit 5720 and ground.
      • If 1 V or greater

        Repair the short to voltage on circuit 5720.

      • Go to next step: If less than 1 V
    5. Replace the K9 Body Control Module.
    • Go to next step: If the Test lamp turns on and off 
  7. Replace the S38 Vehicle On/Off Switch.
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