Chery A15. Manual — part 31

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

Installation: to be fixed by the support of bracket
under pilot trench of front windshield. Pay attention to
waterproofing.

Functions:

Multipoint sequential injection
Controlling ignition
Idle speed control
Independent knocking control on cylinder-by-cylinder
basis (knock sensor KS-1);
Providing sensors with power supply: 5V/100mA
Adopting cylinder-detecting signal (Phase sensor PG1)

λ

closed-loop control with self-adaptation

Controlling carbon canister control valve
Air conditioning switch
Engine-fault indicating lamp
Fuel quantitative correction
Engine speed signal output (TN signal)
Speed signal input
Failure self-diagnosis with flash code function
Accepting engine load signal

Troubleshooting: due to the fact that ECU (electric
control unit) has low failure rate, so generally it is not
advisable to replace ECU for troubleshooting on any
problem. Failure of components such as periphery
circuit and sensors shall be checked and solved firstly.
Do not replace ECU until all periphery components
are confirmed to be fault-free.

Description of pins of ECU:

Pin

Connection point

Type

Pin

Connection point

Type

1

Heated oxygen sensor

Output

42

A/C temperature sensor

Input

2

Ignition coil 2

Output

43

3

Ignition ground wire

Ground

44

Non-sustained power

supply

Input

4

45

Non-sustained power

supply

Input

5

Ignition coil 1

Output

46

Carbon canister Valve

Output

G-13

6

Fuel injector 4 (the 2

nd

cylinder)

Output

47

Fuel injector 3 (the 4

th

cylinder)

Output

7

Fuel injector 2 (the 3

rd

cylinder)

Output

48

8

Output of engine speed

signal

Output

49

9

50

Control of low speed fan Output

10

51

Electronic ground 2

Ground

11

52

12

Sustained power supply

Input

53

Electronic ground 1

Ground

13 Ignition

switch Input

54

14

The main relay

Output

55

15

Engine rotary sensor A

Input

56

16

Throttle position sensor

Input

57

A/C compressor switch

Input

17

Sensor ground 1

Ground

58

18

Oxygen sensor

Input

59

Speed signal

Input

19 Knock

sensor

A Input

60

20

Knock sensor B

Input

61

Power ground 1

Ground

22

63

Non-sustained power

supply

Input

23

64

Phase angle sensor D of

step motor

Output

24

65

Phase angle sensor A of

step motor

Output

25

66

Phase angle sensor B of

step motor

Output

26

67

Phase angle sensor C of

step motor

Output

27

Fuel injector 1 (1

cylinder)

Output

68

Control of high speed fan Output

28

69

Fuel pump relay

Output

29

Inspection light

Output

70

A/C compressor relay

Output

30

71

Diagnostic K wire

I/O

31

72

32

5V power supply 2

Output

73

33

5V power supply 1

Output

74

34

Engine rotary sensor B

Input

75

A/C switch

Input

35

Sensor ground 3

Ground

76

Blaster switch

Input

36

Sensor ground connector

2

Ground

77 Headlight

switch Input

37

Air intake pressure

sensor

Input 78

38

79

Phase angle sensor

Input

39

Temperature sensor of

engine coolant

Input 80

Power ground connector

2

Ground

40

Temperature sensor of

air intake

Input 81

41

G-14

※Electrical fuel pump

Function: Supply the fuel from the fuel tank to the
engine at required pressure and flow (vary from
individual system).

Structure and working principle: The electrical fuel
pump is comprised of direct current motor, vane pump
and end cover (integrated with non-return valve, release
valve and anti-electromagnetic interference elements).
The pump and the motor are mounted on the same shaft
and sealed in the same house. The pump and motor are
surrounded by the gasoline for cooling and lubrication.
The battery supplies power to the electrical fuel pump
through the fuel pump relay and the pump relay
switches on the circuit of the electrical fuel pump only
during start-up and operation of the engine. If the
engine stops running due to malfunction, the fuel pump
will stop operation automatically. The maximum
pressure at exit of the electrical fuel pump is
determined by the release valve within the range of
450-650 kPa. However the pressure of the whole fuel
system fluctuates along with fluctuation of the air
intake manifold pressure. The difference between the
system pressure and the air intake manifold pressure,
which normally is 350kPa, is determined by the fuel
pressure regulator.

Note: The temperature of fuel has a large impact on
performance of the fuel pump. When running under
high temperature for a long time, if the fuel temperature
is higher than a certain temperature, the pressure of the
fuel pump will be decreased rapidly. So please check
carefully whether the performance of the fuel pump
under high temperature is good if the engine fails to hot
start.

Pins: The electrical fuel pump has two pins connecting
to the fuel pump relay. Beside these 2 pins there are
marks of “+” and “-” on the shell of the fuel pump
respectively, which represent the positive and negative
grid.
The 70# pin of ECU controls the fuel pump relay.

Electrical fuel pump

Circuit diagram of the electrical fuel

G-15