2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 508Get this manual
LIGHTSSWITCHES (After '05) Fan motor does not start Disconnect the ECT sensor connector and ground it with jumper wireStart the engine and check the fan motor If the fan motor starts, check the ECT sensor (page 24-13) If the fan motor does not start, check for an open circuit in the following wire:Green wire between the fanICM and fan motor connectorsGreen wire of the fan motor ECT SENSOR CONNECTOR
If the wire is OK, disconnect the fan motor 2P blue connectorStart the engine and measure the voltage between the Black wire terminal (+) and Green wire terminal (-) of the wire harness side connector If there is generating voltage, replace the fan motor If there is no voltage, check for an open circuit in the black wire between the fan motor and ignition switch connectorsIf the black wire is OK, replace the fanICM