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Circuit/System Testing

WARNING: This page is about a different car, the 2020 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
  1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the B55 Engine Compartment Cover Switch.
  2. Verify a test lamp illuminates between ground circuit terminal 3 and B+.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on circuit 750 or the ground connection.
    • Go to next step: If the test lamp illuminates 
  3. Ignition ON, Vehicle in Service Mode
  4. Test for greater than 12 V between the signal circuit terminal 1 and ground
    • If 12 V or less 
    1. Test circuit 4063 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 4063 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 K20 Engine Control Module.
    • Go to next step: If greater than 12 V 
  5. Test or replace the B55 Engine Compartment Cover Switch.
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