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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 >> Power Mode Mismatch >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

KR76 Accessory Time Delay Cutoff Relay

  1. Ignition Off, all accessories Off.
  2. Remove the KR76 Accessory Time Delay Cutoff Relay.
  3. Verify a test lamp illuminates between ground terminal 85 and B+.
    • If the test lamp does not illuminate 
    1. Test for open/high resistance in ground circuit 1350.
      • If open/high resistance is found, repair the circuit or ground connection.
      • Go to next step: If open/high resistance is not found
    2. Replace the X51A Fuse Block - Instrument Panel.
    • Go to next step: If the test lamp illuminates 
  4. Ignition ON, Run Mode,
  5. Verify a test lamp illuminates between control circuit terminal 86 and ground.
    • If the test lamp does not illuminate 
    1. Ignition OFF.
    2. Test for a short to ground in control circuit 4083.
      • If a short is found, repair the circuit.
      • Go to next step: if a short to ground is not found
    1. Test for open/high resistance in control circuit 4083.
      • If open/high resistance is found, repair the circuit.
      • Go to next step: If open/high resistance is not found.
    2. Replace the K9 Body Control Module.
    • Go to next step: If the test lamp turns On 
  6. Open the drivers door latch.
  7. Cycle the Ignition between, Run Mode and Off Mode.
  8. Verify a test lamp turns On and Off between control circuit terminal 86 and ground.
    • If the test lamp is always On 
    1. Ignition ON Run Mode.
    2. Test for a short to voltage in control circuit 4083.
      • If a short to voltage is found, repair the circuit.
      • Go to next step: If a short to voltage is not found.
    3. Replace the K9 Body Control Module.
    • Go to next step: If the test lamp turns On and Off 
  9. Test or replace the KR76 Accessory Time Delay Cutoff Relay.

KR73 Ignition Main Relay

  1. Ignition and all accessories OFF.
  2. Remove the KR73 Ignition Main Relay.
  3. Verify a test lamp illuminates between ground circuit terminal 85 and B+.
    • If the test lamp does not illuminate 

      Repair the open/high resistance on circuit 1350 or the ground connection.

    • Go to next step: If the test lamp illuminates 
  4. Ignition ON vehicle in Run Mode.
  5. Verify a test lamp turns on between the control circuit terminal 86 and Ground.
    • if the test lamp does not illuminate 
      NOTE:

      It may be necessary to disconnect the K9 Body control Module and K56 Serial Data Gateway Module when diagnosing a short on control circuit 5199.

    1. Ignition Off.
    2. Test the relay control circuit 5199 for a short to ground.
      • If a short to ground is found repair the short to ground.
      • Go to next step: if a short to ground is not found
    3. Test the relay control circuit 5199 for an open/high resistance concern.
      • if an open/high resistance is found repair the circuit.
      • Go to next step: if an open/high resistance is not found
    4. Replace the appropriate component.
    • Go to next step: If the test lamp illuminates. 
  6. Open the drivers door latch.
  7. Cycle the Ignition On and Off to place the Vehicle Run Mode and Off Mode.
  8. Verify a test lamp turns On and Off the control circuit terminal 86 and Ground.
    • If the test lamp is always On 
      NOTE:

      It may be necessary to disconnect the K9 Body control Module and K56 Serial Data Gateway Module when diagnosing a short on control circuit 5199.

    1. Turn the Ignition Off.
    2. Test control circuit 5199 for a short to voltage.
      • If a short to voltage is found repair short to voltage on the circuit.
      • Go to next step: if a short to voltage is not found
    3. Replace the appropriate component.
    • Go to next step: If the test lamp turns On and Off 
  9. Test or replace the KR73 Ignition Main Relay.