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Inspection Procedure
21: Abnormal Rotation of Fan Motor
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OPERATION
- The control (duty) signal is inputted to the fan controller (terminal No.
2) from the engine-A/T-ECU (terminal No. 17).
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FUNCTION
- The engine-A/T-ECU inputs a duty signal suitable for the engine coolant temperature,
vehicle speed and A/C switch position to the fan controller. In response to the signal, the
fan controller controls the rotating speeds of the radiator fan and A/C condenser fan (The fan
speed becomes higher as the average voltage of the terminal comes nearer to 5V).
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PROBABLE CAUSE
- Open/short circuit in fan controller circuit or loose connector contact
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| STEP 1. Connector check: C-134 engine-A/T-ECU connector.
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Q: Is the check result normal?
YES:
Go to Step 2  .
NO:
Repair.
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| STEP 2. Check at C-134 engine-A/T-ECU connector.
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- Disconnect connector, and measure at harness side.
- Short-circuit terminal No. 17 to earth.
OK: Fan motor stops rotating.
Q: Is the check result normal?
YES:
Go to Step 3  .
NO:
Go to Step 4  .
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| STEP 3. Check the trouble symptoms.
Q: Does trouble symptom persist?
YES:
Replace engine-A/T-ECU.
NO:
Intermittent malfunction (Refer to GROUP 00 -
How to Use Troubleshooting/Inspection
Service Points  ).
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| STEP 4. Perform voltage measurement at C-134 engine-A/T-ECU connector.
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- Disconnect connector, and measure at harness side.
- Voltage between terminal No. 17 and earth.
OK: 4.9 -
5.1 V
Q: Is the check result normal?
YES:
Replace fan controller.
NO:
Go to Step 5  .
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| STEP 5. Connector check: A-20 fan controller connector
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Q: Is the check result normal?
YES:
Go to Step 6  .
NO:
Repair.
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| STEP 6. Check harness between A-20 (terminal No. 2) fan controller
connector and C-134 (terminal No. 17) engine-A/T-ECU connector.
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NOTE: Before checking harness, check intermediate connector A-14, and repair if necessary.
- Check output line for open circuit.
Q: Is the check result normal?
YES:
Replace fan controller.
NO:
Repair.
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