COOLING FAN ECU > ON-VEHICLE INSPECTION

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1. Inspect the input voltage.
   
   

   1. Disconnect the cooling fan ECU connectors.
      

   2. Turn the ignition switch on.
      

   3. Measure the voltage between terminals +B and GND.
      

      Standard voltage:

      8 to 15 V
      

      If the voltage is not as specified, check the fusible links, fuses, wire harness and fan relay.
      

   4. Reconnect the connectors.
      
      

      HINT:

      Wire harness condition is diagnosed by cooling fan operation.

      
      

      Cooling fan operation	Wire harness condition
      Not in operation	Short
      In continuous operation	Open

2. Check the HV control ECU power source.
   

3. Check RFC1 and RFC2 signal generation.
   

   NOTICE:

   Perform this inspection when coolant temperature is 82°C (180°F)

   
   
   
   
   

   1. Connect an oscilloscope to terminals RFC1 (RFC2) and E1 of the HV control ECU.
      

   
   
   

   2. Check the signal generation and measure the current according to the value(s) in the table below.
      
      

      Condition	RFC1 (RFC2) signal generation	Fan operation	Fan operation
      Engine stopped, IG switch ON	-	-	Not operate
      Engine idling, A/C ON	-	-	Not operate
      Engine idling, A/C ON	See Diagram 1	3 to 13 A	Operate
      Engine idling, engine coolant temperature sensor connector disconnected	See Diagram 2	3 to 21 A	Operate (High speed)

      HINT:

      1. If RFC1 (RFC2) signal is not as specified, replace the HV control ECU.
         
      2. When the fan amperage has a problem even if the RFC1 (RFC2) signal that has no problem, replace the cooling fan ECU.