LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2021 >> CT4 V, RWD >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Shift Lock Control System >> Diagnostic Information and Procedures >> Transmission Control Lever Malfunction >> Circuit/System Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit/System Testing

  1. Ignition OFF, disconnect the X1 connector at the K9 Body Control Module.
  2. Ignition ON/vehicle in service mode, verify a test lamp illuminates between B+ circuit terminal 25 and ground.
    • If the test lamp does not illuminate and the circuit fuse is OK 
    1. Test circuit 2140 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • If an open/high resistance is not found, verify there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Test circuit 2140 for a short to ground.
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Replace the K9 Body Control Module.
    • Go to next step: If the test lamp illuminates 
  3. Ignition/vehicle OFF, connect the X1 connector at the K9 Body Control Module.
  4. Disconnect the connector at the S3 Transmission Shift Lever.
  5. Verify a test lamp illuminates between ground circuit terminal 2 and B+.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on circuit or ground connection.
    • Go to next step: If the test lamp illuminates 
  6. Connect a test lamp between control circuit terminal 4 and ground, ignition ON/vehicle in service mode.
  7. Verify the test lamp turns ON and OFF while pressing and releasing the brake pedal.
    • If the test lamp is always OFF 
    1. Test circuit 7553 for a short to ground.
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Test circuit 7553 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. Replace the K9 Body Control Module.
    • If the test lamp is always ON 
    1. Test circuit 7553 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the K9 Body Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  8. Replace the S3 Transmission Shift Lever.
scientia non olet · About LEMON Manuals