Inspection Procedure 21: Abnormal Rotation of Fan Motor

OPERATION

• The control (duty) signal is inputted to the fan controller (terminal No. 2) from the engine-ECU <M/T> or engine-A/T-ECU <A/T> (terminal No. 17).
  

FUNCTION

• The engine-ECU <M/T> or engine-A/T-ECU <A/T> 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).
  

PROBABLE CAUSE

• Failed fan controller
  
• Open/short circuit in fan controller circuit or loose connector contact
  
• Failed engine-ECU <M/T>
  
• Failed engine-A/T-ECU <A/T>
  

Q. Is the check result normal? Go to Step 2 . Repair or replace.

Disconnect connector, and measure at harness side. Ignition switch: ON Short-circuit terminal No. 17 to earth. OK: Fan motor stops rotating. Q. Is the check result normal? Go to Step 3 . Go to Step 4 .

	Replace engine-ECU <M/T> or engine-A/T-ECU <A/T>.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).

Disconnect connector, and measure at harness side. Ignition switch: ON Voltage between terminal No. 17 and earth. OK: 4.9 - 5.1 V Q. Is the check result normal? Replace fan controller. Go to Step 5 .

Q. Is the check result normal? Go to Step 6 . Repair or replace.

note Before checking harness, check intermediate connector A-16, and repair if necessary. Check output line for open circuit. Q. Is the check result normal? Replace fan controller. Repair.