Maintenance Manual for Chery·Windcloud M7.9.7 EFI System
3. Coolant Temperature Sensor TF-W
Purpose: this sensor is designed to provide
coolant temperature information. To provide
engine ECU with water temperature signal
used for control of ignition timing and fuel
injection pulse width in startup, idle speed
and normal operation.
Composition and principle: this sensor is a
thermistor of negative temperature
coefficient (NTC) with resistance value
decreasing with the increasing of coolant
temperature except linear relation. The said
thermistor is installed in a heat-conducting
sleeve. ECU monitors water temperature
variation by converting resistance value of
thermistor into a changing votage through a
bleeder circuit (inner structure of ECU).
Failure diagnosis: When coolant
temperature is higher than allowed upper
limit or lower than lower limit, failure mark
of the knock sensor is set, engine fault
indicating lamp goes on and engine works in
failure mode. In this case ECU controls
ignition and fuel injection according to set
water temperature for failure mode, at the
same time the fan is running at high-speed
mode.
Limiting data: 2.5±5%KΩ
Installation hint: tightening torque is 15Nm
in maximum.
Hints: the vehicle is equipped with 2 water
temperature sensors, one is single-pin water
temperature sensor, providing the water
temperature gauge with water temperature
signal; the other is double-pin, providing the
engine ECU with water temperature signal.
Coolant temperature sensor
Coolant
temperature
sensor
Circuit diagram of coolant temperature sensor
Pins: this sensor has 3 pins, which can
interchange for use.
1 coolant temperature sensor signal (ECU
39#)
2 sensor signal ground (ECU 35#)
3 another line connects water temperature
signal of gauge.
Troubleshooting: mainly check if there is
short circuit or open circuit on the
connection between 3 lines, ECU and
gauge on senosr.
If there is short circuit, open circuit or
grounding between sensor wire harnesses.
Line grounding or defect grounding is liable
to cause engine water temperature gauge to
indicate excessive temperature.
3
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