Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
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z The temperature resistor of the temperature sensor is one part of the 5V
voltage division circuit. Two terminals of the temperature sensor is
connected with the voltage charged circuit. When the temperature
resistor of the temperature sensor changes along with the temperature,
the voltage of the voltage charged circuit changes accordingly, which
will be inputted to the analog/digital conversion circuit of ECU
interface circuit. The relationship characteristic curve between voltage
and temperature is stored in the ECU of engine management system;
z Sunray is equipped with 3-wire water temperature sensor to save the
cost and guarantee the system unity.
2) Working Principle
The coolant temperature sensor is used to measure the working temperature of the engine. The ECU will provide the
engine with best control scheme, depending on different temperatures.
This sensor is one negative temperature coefficient (NTC) thermistor, of which the resistance reduces following the
increasing of coolant temperature in a non-linear mode. The negative temperature coefficient thermistor is installed
within one copper heat conducting sleeve. By means of one voltage division circuit, the ECU converts the resistance
change of thermistor to one varying voltage and provides to the ECU and thus monitors the change of water
temperature (internal structure of ECU).
3) Measurement analysis
Wiring terminals: 1 – Temperature signal; 2 – Grounding
Reference values: -10℃ 8.642---10.152 kΩ
20℃2.351---2.649 kΩ
80℃0.313---0.332 kΩ
4) Malfunction Mode
Upon the detection that the water temperature signal is higher or less than the limit range, the ECU will light up the
malfunction indicator lamp.
5) Troubleshooting
Sunray is fitted with one independent coolant temperature sensor to transmit the water temperature signal to the
instrument for display of instrument water temperature alarm. If the water temperature alarm indicator lamp lights up,
stop for cooling immediately. If the water temperature alarm indicator lamp lights up frequently, drive to the
authorized service station of JAC Multifunctional Commercial Vehicle Company for service.
7. Water level sensor
1) Overview
z The fuel-water separator position sensor is functioned to measure the water content in the fuel filter;
z When the water content reaches a predefined level, the ECU will control the working of the engine. This sensor
is installed on the bottom of the fuel filter;
Characteristic curve of tem
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