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Home >> Chevrolet >> 1996 >> Caprice Impala SS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests 5.7L >> C-10 & C-12 Diagnostic Tests >> C-12, Cooling Fan Circuit Diagnosis - Except FLEETWOOD >> Cooling Fan Circuit Diagnosis

Cooling Fan Circuit Diagnosis

  1. Perform On-Board Diagnostics (OBD) System check. See BASIC TESTING article. After performing OBD system check, go to next step.
  2. Check for PCM Diagnostic Trouble Codes (DTCs). If any codes are present, perform testing for applicable code. Some DTCs will cause fans to come on at all times. Repair all DTCs that are set before proceeding with testing. See TESTS W/CODES article. If no codes are present, go to next step.
  3. Ensure engine coolant temperature is less than 212°F (100°C). Turn A/C off. If cooling fans are off, go to next step. If cooling fans are on, go to step 6).
  4. Using scan tool, command cooling fan relay(s) on. If cooling fans turn on, go to next step. If cooling fans do not turn on, go to step 9).
  5. With engine at idle, turn A/C on. If cooling fans turn on, system is operating normally at this time. If cooling fans do not turn on, diagnose A/C compressor clutch.
  6. Disconnect cooling fan relay for cooling fan that is operating. If fan stops, go to next step. If fan does not stop, go to step 8).
  7. Replace fan relay.
  8. Repair circuit between fan relay and fan motor for a short to voltage.
  9. Turn ignition off. Disconnect cooling fan relay for cooling fan that is not operating. Turn ignition on. Using test light connected to ground, probe battery feed side of cooling fan relay electrical harness. If test light does not illuminate, go to step 16). If test light illuminates, go to next step.
  10. Connect fused jumper wire between cooling fan relay electrical harness, battery feed circuit, to fan motor circuit. Leave jumper wire in place for remainder of testing. If fan does not operate, go to next step. If fan operates, go to step 17).
  11. Turn ignition off. Disconnect cooling fan electrical connector for fan that is not operating. Turn ignition on. Connect test light between cooling fan electrical connector terminals. If test light does not illuminate, go to next step. If test light illuminates, go to step 18).
  12. Connect test light between ground and cooling fan harness connector power feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 15).
  13. Check fan motor harness connection. Repair as necessary. If connection is okay, go to next step.
  14. Repair open circuit in fan motor ground circuit.
  15. Repair open circuit in power feed between fan relay and fan motor.
  16. Repair open battery feed circuit to fan relay.
  17. Replace fan relay.
  18. Replace fan motor.
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