Chery A series. Manual — part 30

Pins:

1 sensor signal ground (ECU17#)
2 5V power (ECU32#)
3 sensor signal (ECU16#)

Troubleshooting: mainly check if there is short circuit
or open circuit on the connection between 3 lines on
sensor and ECU.
Check to see if there is short circuit, open circuit or
grounding between sensor wire harnesses.

※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 voltage 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.

Coolant Temperature Sensor

Circuit diagram of Coolant

temperature sensor

G-9

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.

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 sensor.
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.

※Knock Sensor KS

Purpose: this sensor is designed to provide ECU with
engine knocking information so as to carry out
knocking control.

Composition and principle: knock sensor is a sort of
vibration acceleration sensor, which is fixed on engine
cylinder block. ECU controls engine ignition via
signals detected by pressure-sensing element.

Failure diagnosis: ECU monitors on various sensors,
actuators, power amplification circuits and sensing
circuits. In case any of the following situations occurs,
failure mark of the knock sensor is set.
Knock sensor failure
Knocking control data processing circuit failure
Cylinder-detecting signal is unreliable
After failure mark of knock sensor being set, knocking
closed-loop control is shut down, reducing a safety
angle from the ignition advance angle stored in ECU.
When error frequency cuts down to below setting

KS with cable

1.Knocking

block

2.Casing

3.Piezoelectric

ceramics

4.Contactor

5.Electric

connection

Circuit diagram of knock sensor

G-10

value, failure mark restores.

Installation hint: tightening torque is 20±5Nm.

Pins:

1 Knock sensor signal 1 (ECU19#)
2 Knock sensor signal 2 (ECU20#)

Troubleshooting: mainly check if there is short circuit
or open circuit on the connection between 2 lines on
sensor and corresponding ECU pins.
If gasket is added during installation; if tightening
torque is proper.
If there is stitching defect between sensor and cylinder,
or there is foreign matter between them.

※Oxygen Sensor

Purpose: this sensor is designed to provide the
information that if there is surplus oxygen after full
combustion of fuel, which is injected into engine
cylinder in the intake air. ECU, when applying this
information, can carry out fuel quantitative
closed-loop control so as to achieve utmost conversion
and purification of the three major toxic elements (HC,
CO and NOX) in the engine exhaust with the
application of three-way catalytic converter.

Composition and principle: the sensing element of
oxygen sensor is a porous ceramic pipe, the outer side
of pipe wall is surrounded by engine exhaust, while
inner side vents to atmosphere. According to inside
and outside oxygen concentration difference, sensor
figures out indirectly fuel injection pulse width, and
then transfers the information to ECU, and the ECU
controls the injection again.

The working voltage of oxygen sensor fluctuates
between 0.1-0.9V, 5-8 variations in 10 seconds is
required; if lower than such frequency value, it shows
that the sensor is aged, and needs replacement. The
said sensor is unrepairable.

Failure diagnosis: ECU monitors on various sensors,
actuators, power amplification circuits and sensing
circuits. In case any of the following situations occurs,
failure mark of the oxygen sensor is set.
Accumulator voltage is unreliable

Oxygen Sensor

Circuit diagram of Oxygen sensor

G-11

Manifold absolute pressure signal is unreliable
Engine coolant temperature signal is unreliable.
Injector driver stage failure
After oxygen sensor failure mark is set, fuel
quantification closed-loop control is shut down, and
the primitive fuel injection time stored in ECU is used
to carry out fuel quantification.

Installation hints: the tightening torque of oxygen
sensor is 50-60Nm, a layer of rust preventive oil shall
be applied on oxygen sensor after replacing so as to
prevent from incapable removal in case of rust.

Troubleshooting: mainly check if the plug connection
of several wires on the sensor is in good condition, and
if there is short circuit or open circuit.
Generally, sensor damage is caused by plumbum and
phosphorus poisoning, so pay attention to fuel quality,
meanwhile excessive consumption of engine oil is
Oxygen sensor has a cable, the other end of which is
electric connection. The outside of sensor is wrapped
with asbestos fireproof covering.

There are 4 pins on the joint:

1# connecting with heating control (ECU1#);
2# connecting with heating power and main relay;
3# connecting with sensor ground (ECU36#);
4# connecting with signal (+) (ECU18#).

※ Electronic Control Unit ECU

Purpose: ECU is the core of electronic engine control
system. Sensors sent various signals to ECU for
electric control, and then ECU controls operations of
fuel injector and ignition coil, etc. after internal
calculation, thus controlling working of engine.

Normal operation voltage: 9-16V

Composition: it has shielded casing and printed
circuit board, which integrates lots of electronic
control units for the control of EFI system.

氧传感器内部构造图

Interior structure of oxygen sensor

ECU

G-12