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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 >> Vehicle Will Not Change Power Mode >> Circuit/System Testing

Circuit/System Testing

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

    If the S38 Vehicle On/Off Amber and/or Green indicators function this step does not need to be performed and you may proceed to the next step.

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

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

    • Go to next step: If the test lamp illuminates 
  3. Connect the S38 On/Off Vehicle Switch.
  4. Ignition On Vehicle in Run mode.
  5. Disconnect the S38 On/Off Vehicle Switch.
  6. Test for between 4.7 v and 5.3 v between the signal circuit terminal 4 and ground.
    • If not the specified value 
      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 5723.

    1. Test the signal circuit 5723 for a short to ground condition.
      • If a short to ground condition is found, repair the short in the circuit.
      • Go to next step: If a short to ground condition is not found
    2. Test the signal circuit 5723 for an open/high resistance condition.
      • If an open/high resistance condition is found, repair the open/high resistance in the circuit.
      • Go to next step: If an open/high resistance condition is not found
    3. Test the signal circuit 5723 for less than 5.9 V.
      • If greater than 5.9 V, repair the short to voltage in the circuit.
      • Go to next step: If less than 5.9 V
    4. Replace the K9 Body Control Module.
    • Go to next step: If the Specified Value 
  7. Connect the S38 On/Off Vehicle Switch.
  8. Ignition Off Vehicle in Off power mode.
  9. Test for 6.0k-7.5K Ω between Signal terminal 4 and ground terminal 3 with the S38 On/Off Vehicle not pressed.
    • If not between 6.0k-7.5K Ω 

      Replace the S38 On/Off Vehicle Switch.

    • Go to next step: If between 6.0k-7.5K Ω 
  10. Test for 1.3k-1.8k Ω between Signal terminal 4 and ground terminal 3 with the S38 On/Off Vehicle Switch pressed.
    • If not between 1.3k-1.8k Ω 

      Replace the S38 On/Off Vehicle Switch.

    • Go to next step: If between 1.3k-1.8k Ω 
  11. Replace the K9 Body Control Module.
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