Engine Coolant Temperature (Ect) Sensor - Honda TRX450R Service Manual

LIGHTS/SWITCHES (After '05)
Fan motor does not start
Disconnect the ECT sensor connector and ground it
with a jumper wire.
Start 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 fan/ICM and fan motor
connectors
- Green wire of the fan motor
If the wire is OK, disconnect the fan motor 2P blue
connector.
Start 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 igni-
tion switch connectors. If the black wire is OK,
replace the fan/ICM.
ENGINE COOLANT TEMPERATURE
(ECT) SENSOR
INSPECTION
Drain the coolant (page 9-7).
Disconnect the ECT sensor connector and remove
the ECT sensor.
Suspend the ECT sensor in a pan of coolant (50 - 50
mixture) on an electric heating element and mea-
sure the resistance through the sensor as the cool-
ant heats up.
NOTE:
• Soak the ECT sensor in coolant up to its threads
with at least 40 mm (1.57 in) from the bottom of
the pan to the bottom of the sensor.
• Keep the temperature constant for 3 minutes
before testing. A sudden change of temperature
will result in incorrect readings. Do not let the
thermometer or ECT sensor touch the pan.
Resistance: 47.5 - 56.8 il at 80°C (176°F)
14.9 - 17.3 Q. at 120°C (248°F)
ECT SENSOR CONNECTOR
FAN MOTOR CONNECTOR
THERMOMETER
ECT SENSOR
24-13