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Home >> Cadillac >> 1997 >> Catera >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests 3.0L >> Circuit Diagnosis Tests >> ECM Cooling Fan Does Not Operate

ECM Cooling Fan Does Not Operate

  1. Locate test connector within the Engine Control Module (ECM) housing. Using a fused jumper wire, connect terminal No. 1 (Brown/Blue wire) of test connector to a known good ground. If ECM cooling fan comes on, go to next step. If ECM cooling fan does not come on, go to step 3).
  2. Check for open circuit or high resistance in Brown/Blue wire and Black wire to temperature switch No. 1. If wires are okay, replace temperature switch No. 1. After repairs, reconnect wiring and components. Verify ECM cooling fan operates properly.
  3. Disconnect ECM relay (K48). Using a DVOM, measure voltage between ground and terminal No. 2 (Red wire) of ECM relay. If battery voltage is present, go to step 5). If battery voltage is not present, go to next step.
  4. Repair open circuit or high resistance in Red wire to ECM relay. After repairing wire, reconnect wiring and components. Verify ECM cooling fan operates properly.
  5. Measure voltage between ground and terminal No. 4 (Brown wire) of ECM relay. If battery voltage is present, go to step 7). If battery voltage is not present, go to next step.
  6. Repair open circuit or high resistance in Brown wire to ECM relay. After repairing wire, reconnect wiring and components. Verify ECM cooling fan operates properly.
  7. Connect a fused jumper wire between terminal No. 4 (Brown wire) and terminal No. 8 (Black/White wire) of ECM relay. If ECM cooling fan comes on, go to next step. If ECM cooling fan does not comes on, go to step 9).
  8. Replace ECM relay. After replacing relay, reconnect wiring and components. Verify ECM cooling fan operates properly.
  9. Disconnect ECM cooling fan. Measure voltage between ground and Black/White wire terminal of ECM cooling fan wiring harness connector. If battery voltage is present, go to step 11). If battery voltage is not present, go to next step.
  10. Repair open circuit or high resistance in Black/White wire between ECM relay and cooling fan. After repairing wire, reconnect wiring and components. Verify ECM cooling fan operates properly.
  11. Measure resistance between ground and Black (ground) wire terminal of ECM cooling fan wiring harness connector. If resistance is less than 2 ohms, go to step 13). If resistance is not as specified, go to next step.
  12. Repair open circuit or high resistance in Black wire to ECM cooling fan. After repairing wire, reconnect and wiring components. Verify ECM cooling fan operates properly.
  13. Replace ECM cooling fan. After replacing fan, reconnect wiring and components. Verify ECM cooling fan operates properly.
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