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Home >> Cadillac >> 2013 >> Escalade Base, AWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 14 (Hybrid/EV Cooling System) >> Diagnostic Information and Procedures >> Hybrid Cooling System Overheating (Electrical) >> Circuit/System Testing

Circuit/System Testing

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  1. Disconnect the coolant pump relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the relay controlled output circuit terminal 87 and ground.
    • If the test lamp illuminates, test the relay controlled output circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the relay coil B+ circuit terminal 85 and ground.
    • If the test lamp does not illuminate, test the relay coil B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay coil B+ circuit fuse is open, test the relay controlled output circuit for a short to ground. If the circuit tests normal, test or replace the coolant pump relay.
  4. Verify that a test lamp illuminates between the relay switch B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate, test the relay switch B+ circuit for an open/high resistance.
  5. Disconnect the harness connector at the appropriate DMCM coolant pump.
  6. Test for less than 5.0 ohms between the coolant pump ground circuit terminal 1 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the coolant pump.
  8. Connect a 15 A fused jumper wire between the relay switch B+ circuit terminal 30 and the relay controlled output circuit terminal 87. Verify the coolant pump is activated.
    • If the coolant pump does not activate, test the relay controlled output circuit for an open/high resistance. If the circuit tests normal, test or replace the coolant pump.
  9. Connect a test lamp between the relay coil B+ circuit terminal 85 and the relay coil control circuit terminal 86.
  10. Command the DMCM coolant pump ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the relay coil control circuit for a short to ground. If the circuit tests normal, replace the ECM.
    • If the test lamp is always OFF, test the relay coil control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  11. If all circuits test normal, test or replace the relay.
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