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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 135 (12 V Starting And Charging - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0615, P0616, or P0617 >> Circuit/System Testing

Circuit/System Testing

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  1. Ignition OFF and all vehicle systems OFF, disconnect the KR27 Starter Relay. It may take up to 2 min for all vehicle systems to power down.
  2. Verify a test lamp illuminates between ground circuit terminal 86 and B+.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on circuit 6450 or the ground connection.
    • Go to next step: If the test lamp illuminates 
  3. Ignition on, connect a test lamp between control circuit terminal 85 and ground.
  4. Verify the test lamp turns ON and OFF while commanding the Starter Motor ON and OFF with the scan tool.
    • If the test lamp is always OFF 
    1. Test circuit 625 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 625 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.
    • If the test lamp is always ON 
    1. Test circuit 625 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 K20 Engine Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  5. Test or replace the KR27 Starter Relay.
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