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Home >> Mazda >> 2004 >> MX-5 Miata Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Symptom Troubleshooting (Engine Control System BP, BP With TC] >> Engine Control System Operation Inspection >> Cooling Fan Control Operation Inspection (BP With TC)
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Cooling Fan Control Operation Inspection (BP With TC)

  1. Connect the WDS or equivalent to DLC-2.
  2. Access the ECT PID.
  3. Verify that the ECT PID is below 100°C {212°F}  .
  4. Verify that the fan motor No. 1 and No. 2 do not operate.
    • If the cooling fans are operating, inspect for following:
      • Short to GND circuit in wiring between A/C switch and PCM terminal 4F.
      • Short to GND circuit in wiring between fan relay No. 1 and PCM terminal 2B.
      • Short to GND circuit in wiring between fan relay No. 2 and PCM terminal 2C.
      • Short to GND circuit in wiring between fan relay No. 3 and PCM terminal 2C.
      • Fan relay No. 1 stuck closed.
  5. Start the engine and warm up it to ECT PID is above 100°C {212°F}  .
  6. Verify that fan motor No. 1 and No. 2 operate.
    • If the fan motor No. 1 and No. 2 do not operate inspect for following:
      • Open circuit in wiring between PCM terminal 2B and fan relay No. 1.
      • Open circuit in wiring between battery positive terminal and fan relay No. 1.
      • Fan relay No. 1 stuck open.
    • If the fan motor No. 1 does not operate inspect for following:
      • Open circuit between fan relay No. 1 and GND through fan motor No. 1.
      • Fan motor No. 1 malfunction.
    • If the fan motor No. 2 does not operate inspect for following:
      • Open circuit between fan relay No. 3 and GND through fan motor No. 2.
      • Fan motor No. 2 malfunction.
  7. Verify that the fan motor No. 1 and No. 2 operate high speed while the A/C is operating.
    • If the fan motor No. 1 and No. 2 do not operate high speed, inspect for following:
      • Open circuit between A/C switch and PCM terminal 4F.
      • Open circuit between PCM terminal 2C and fan relay No. 2.
      • Open circuit between PCM terminal 2C and fan relay No. 3.
      • Open circuit between battery positive terminal and fan relay No. 2.
      • Open circuit between battery positive terminal and fan relay No. 3.
      • Open circuit between fan relay No. 2 and GND.
      • Fan relay No. 2 stuck open.
      • Fan relay No. 3 stuck open.
    • If the fan motor No. 1 does not operate high speed, inspect for following:
      • Open circuit between fan relay No. 2 and fan motor No. 1.
      • Open circuit between fan relay No. 3 and fan motor No. 1.
      • Fan motor No. 1 malfunction.
    • If the fan motor No. 2 does not operate high speed, inspect for following:
      • Open circuit between fan relay No. 2 and fan motor No. 2.
      • Open circuit between fan relay No. 3 and fan motor No. 2.
      • Fan motor No. 2 malfunction.
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