Lifan 620. Manual — part 6

(1) Function:

To provide information on coolant temperature. To provide water temperature signal

for the ECU, and to control ignition timing and fuel injection pulse width at start, idle speed, and
normal operation.

(2) Structure and principle:

Made by a thermistance with NTC. The resistance value will

decrease with the increase of the coolant temperature (not a linear relation). The thermistance
with NTC is installed within a copper sleeve. With a voltage division circuit, the resistance value of
the thermistance is converted into a changing voltage and then provided to the ECU, and then the
change of water temperature can be monitored (internal structure of ECU).

(3) Connection of wiring diagram (Fig. 1-6)

KS1-7

(1) Function:

To provide engine knock information for the ECU for knock control.

(2) Structure and principle:

As a vibration acceleration sensor, installed on the cylinder block of

the engine. The sense element of the sensor is a piezoelectric element. The vibration of the
cylinder block of the engine can be transferred to the piezoelectric crystal through the mass block
within the sensor. Under the mass block vibration pressure, voltage will be produced at the two

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(5) Installation notes:

The tightening torque for installation is 20±5N·m.

5. Oxygen sensor

(Fig. 1-8)

Fig. 1-8

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(1) Function:

To provide the information that whether oxygen in the cylinder is too high after the

fuel is burned with the air in the cylinder. With this information, the ECU can carry out closed loop
control for the fuel ration. Therefore, the three main toxic elements (HC, CO, and NOX) of the
engine exhaust can be best converted and purified in the three-way catalytic converter.

(2) Structure and principle:

The sense element of the oxygen sensor is a ceramic pipe with holes

Fig. 1-9

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(4) Trouble diagnosis:

The ECU will monitor the sensors, actuators, power amplifying circuit and

detecting circuit. In case of any of the following situations, like unreliable battery voltage,
unreliable air intake manifold absolute pressure singal, unreliable engine coolant temperature
signal, fuel injector driving stage trouble, incorrect oxygen sensor trouble mark level, and fuel
ration closed loop control closed, the fuel ration will be confirmed according to the basic fuel
injection time stored in the ECU.
(5) Installation notes:

The tightening torque of the oxygen sensor is 50～60N·m. Apply anti-rust

oil to the renewed oxygen sensor to prevent difficult removal due to rust.

(4)

Pin

2

J1-22 Trouble

indicator

J1-23 Not

used

J1-24 Throttle

position

J1-25

Not used

J1-26

Not used

J1-27

Intake air temperature

J1-28

Crankshaft 58 teeth signal

low

J1-29 Not

used

J1-30 Not

used

J1-31 Engine

trouble

indicator

J1-32 Ignition

switch

A

J1-33

Idle speed phase B

output positive

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