Cooling Fan Ecu On-Vehicle Inspection

Inspect the input voltage.

1. Disconnect the cooling fan ECU connector.
   

2. Turn the ignition switch on (IG). Check the voltage of the +B terminal of the disconnected wire harness side connector.
   

   Standard voltage:

   9 to 14 V
   

   If the result is not as specified, inspect the power source system (fusible link, fuse, wire harness and relay).
   

Inspect the cooling fan motor (CAMRY_ACV40 RM000000YFJ00YX.html).

Measure the resistance between terminals RFC (ECM) and SI (cooling fan ECU) of the wire harness side connectors.

HINT:

1. If the fan does not operate, there may be a short circuit.
   
2. If the fan remains operating, there may be an open circuit.
   

Inspect the ECM power source circuit and ground circuit.

Inspect the input signal and output current.

NOTICE:

Be sure to perform the inspection with the radiator coolant temperature less than 95°C (203 °F).

1. Connect the 400 A probe of the ammeter to terminal M+ of the cooling fan motor.
   

2. Set the intelligent tester to the oscilloscope function.
   

3. Using the intelligent tester, check the waveform between terminals RFC and E1 of the ECM.
   

   Standard waveform:

   Condition	Input Signal	Output Current
   Engine stopped (Ignition switch on (IG))	Waveform 1 (Duty ratio 0 %)	(Fan stops)
   Engine idling (A/C OFF)	Waveform 1 (0 %)	(Fan stops)
   Engine idling (A/C ON)	Waveform 2 (30 to 70 %)	2 to 11 A (Fan operates)
   Engine idling (Coolant temperature sensor connector disconnected)	Waveform 3 (30 to 70 %)	2 to 11 A (Fan operates)

   HINT:

   1. If the input signal is abnormal, there is a malfunction in the ECM or cooling fan ECU.
      
   2. If the output current is abnormal even when the input signal is normal, there is a malfunction in the cooling fan ECU (RFC) or motor.