Chery QQ6 (UMC EFI for 473F Engine). Service Manual — part 4

11.12 Ignition Coil Failure

No.

Operating steps

Result

Follow up steps

1

Put the ignition switch to “ON”.

Next step

Yes

Next step

2

Pull out ignition coil joint on harness, and then use

a multimeter to check if the voltage between 3#

pin of this joint and ground wire is an around 12V

battery voltage.

No

Check the circuit

Yes

Check circuit and

ECU

3

Pull out ignition coil joint on harness, and then use

a multimeter to check if it is short or break circuit

between 1# pin of this joint and 5# pin of ECU.

No

Next step

Yes

Check circuit and

ECU

4

Pull out ignition coil joint on harness, and then use

a multimeter to check if it is short or break circuit

between 2# pin of this joint and 2# pin of ECU.

No

Next step

Yes

Next step

5

Check if the resistance of primary coil of the

sensor is around 0.9Ω.

No

Replace the ignition

coil

Yes

Next step

6

Check if the resistance of secondary coil of the

sensor is around 14.5kΩ.

No

Replace the ignition

coil

Yes

Check other part

7

Use an oscillometer to check if secondary ignition

waveform of ignition cable of ignition system is

normal.

No

Replace the ignition

coil

Note: The ignition coil is mainly used to provide ignition system of engine with ignition energy. The

failure rate of the coil itself is very low, but its failure probability can not be completely excluded. When

failure occurs in ignition coil, the ignition energy of engine will be deficient, which may further lead to

such failures as unsteady idle speed of engine and emission deterioration.

11.13 Accelerator Pedal Position Sensor Failure

Failure codes: P2106, P2122, P2123, P2127, P2128, P2138

No.

Operating steps

Result

Follow up steps

1

Put the ignition switch to “ON”.

Next step

Yes

Next step

2

Pull out accelerator pedal position sensor joint on

harness, and then use a multimeter to check if an

around 5V voltage signal is present between 3#,

6# pins of this joint and ground wire.

No

Check the circuit

Yes

Check the circuit

3

Pull out accelerator pedal position sensor joint on

harness, and then use a multimeter to check if it is

short or break circuit between 3#, 6# pins of this

joint and 32#, 33# pins of ECU.

No

Next step

Yes

Check the circuit

4

Pull out accelerator pedal position sensor joint on

harness, and then use a multimeter to check if it is

short or break circuit between 2#, 5# pins of this

joint and 36#, 35# pins of ECU.

No

Next step

Yes

Check the circuit

5

Pull out accelerator pedal position sensor joint on

harness, and then use a multimeter to check if it is

short or break circuit between 4#, 1# pins of this

joint and 16#, 40# pins of ECU.

No

Next step

Yes

Next step

6

Use a diagnostic tester to read signal output of

accelerator pedal position sensor, and then check

if signal 1 increases as opening of accelerator

pedal increases.

No

Replace the sensor

assembly

Yes

Check other part

7

Use a diagnostic tester to read signal output of

accelerator pedal position sensor, and then check

if signal 2 increases as opening of accelerator

pedal increases.

No

Replace the sensor

assembly

Note: This pedal is an integrated circuit device, which can not be processed through repair; therefore,

during maintenance process, the service station can maintain it by means of part replacement and can not

disassemble the sensor.

11.14 Double Brake Switch

Failure codes: P0571, P0504

No.

Operating steps

Result

Follow up steps

1

Put the ignition switch to “ON”.

Next step

Yes

Next step

2

Pull out brake switch joint on harness, and then

use a multimeter to check if it is short or break

circuit between 1#, 2# pins of this joint and 21#,

58# pins of ECU.

No

Check the circuit

Yes

Next step

3

Close the ignition switch, and then check if an

around 12V battery voltage is present on 3# pin of

the switch joint.

No

Check the circuit

Yes

Next step

4

Open the ignition switch, and then check if an

around 12V battery voltage is present on 4# pin of

the switch joint.

No

Check the circuit

Yes

Next step

5

Release brake pedal, disconnect sensor connector,

and then check if 1# and 3# pins cut off.

No

Replace the brake

switch

Yes

Next step

6

Release brake pedal, disconnect sensor connector,

and then check if 2# and 3# pins conducts.

No

Replace the brake

switch

Yes

Next step

7

Apply brake pedal, disconnect sensor connector,

and then check if 1# and 3# pins conducts.

No

Replace the brake

switch

Yes

Check other part

8

Apply brake pedal, disconnect sensor connector,

and then check if 2# and 4# pins cut off.

No

Replace the brake

switch

11.15 Theft-proof Control System Failure

No.

Operating steps

Result

Follow up steps

1

Insert the ignition key into the ignition lock.

Next step

Yes

Check other part

2

Put the ignition switch to ON position, and then

observe if engine failure indicator lamp or EPC

lamp works normally (quick flash of failure

indicator lamp or EPC lamp indicates a abnormal

condition).

No

Next step

Yes

Remove the failure

and clear the DTC

3

Connect a diagnostic tester to the system, and then

enter corresponding diagnostic program unit to

check if DTC exists in the system.

No

Next step

Yes

Next step

4

Pull out theft-proof module joint on harness, and

then use a multimeter to check if an around 12V

operating voltage is present on A1#, A4# pins of

the joint when ignition switch is under ON state.

No

Check the circuit

Yes

Check the circuit

5

Pull out theft-proof module joint on harness, and

then use a multimeter to check if such electric and

circuit failures as short circuit and break circuit

exist in the circuit between A5#, A8# pins of this

joint and 31# and 71# pins of ECU.

No

Next step

Yes

Check the circuit

6

Pull out theft-proof module joint on harness, and

then use a multimeter to check if poor contact

exists between A2# pin of this joint and ground

wire of the vehicle.

No

Next step

Yes

Check the circuit

7

Pull out theft-proof module joint on harness, and

then use Ohm Shift of the multimeter to check if

the circuit between B1#, B2#, B3# pins of this

joint and the coil exists.

No

Replace

the

theft-proof module

12. Steps for Implementation of Failure Diagnosis by Engine

Symptom

12.1 Perform Preliminary Inspection First before Following the Steps for
Implementation of Failure Diagnosis by Engine Symptom.

(1) Make sure that ECU and failure indicator lamp (or EPC lamp) have no off-normal
phenomenon (excluding the models that have no failure indicator lamp).
(2) Use a failure diagnostic tester to check and make sure no failure information record
exists.
(3) Employ failure diagnostic tester to check that hot idle data from electronic control
system fall within normal scope.

Hot idle speed parameter table:

Name

Parameter

Air intake temperature

20-70℃

Battery voltage

12-14V (affected by engine revolution)

Temperature of engine coolant

80-90

(normal operating temperature)

℃

Position of accelerator pedal

0%~99.00%

Air-fuel ratio control integrator

5%-5%

Ignition advance angle

5-10

° (

may change with fluctuation of

engine revolution)

Outer corner of throttle

0%~99.61%

Fuel injection time

2-7ms (has a strong relation with engine
revolution)

Engine revolution n

Expected idle speed ± 50rpm

Duty cycle of canister control valve

0%~99.9%

Self-adapting value of air-fuel ratio
control

0.95-1.05

Self-adapting value of air-fuel ratio
control

120-140

Intake manifold absolute pressure

350-650hPa

Voltage of oxygen sensor

Quickly fluctuates at 0.1-0.9V

Air intake pressure

(4) Validate that the failure effect the owner complained exists and then locate the exact
position of the symptom. Please note that the information provided by the customer is
very important, especially the failure symptoms, occurrence time, position and if any
other failure symptoms occurred before; these information can help technical personnel
rapidly and effectively judge the failure, thus increasing maintenance speed and
improving maintenance quality.
Then check the appearance:

Check that grounding of wire harness is clean and firm.
Check that vacuum pipeline is unbroken, twisted and in right connection.
Check that there is no obstruction in pipe.
Check that air intake pipe is not squashed or damaged.
Check that the seal between throttle body and intake manifold is perfect.
Check that ignition cable of ignition system is unbroken, no ageing and in right wiring.
Check that wires are in right connection, no loosing or poor connection for connectors.

12.2 The Engine Does not Rotate or Rotates Slowly when Starting

No.

Operating steps

Result

Follow up steps

Yes

Next step

1

Use a multimeter to check if a voltage around

10-12.5V is present between two battery

terminals.

No

Repair

or

replace

the

battery

Yes

Next step

2

Put the ignition switch to “ON”. Use a

multimeter to check if a battery voltage around

10-12.5V is present on the terminal on the

ignition switch that connects with anode of

battery.

No

Repair

wiring

terminal

or

replace cable

Yes

Next step

3

Maintain ignition switch at START position,

and then use a multimeter to check if a voltage

above 8V is present on the terminal on the

ignition switch that connects with pull in

winding of starting motor.

No

Replace

the

ignition switch

Yes

Next step

4

Put the ignition switch at start position, check

the anode terminal of starting motor by

multimeter and observe the voltage if it is above

8V.

No

Repair

wiring

terminal

Or

replace

cable

Yes

Repair

or

replace

the

starting motor

5

Check if it is short circuit or break circuit in the

starting motor.

No

Next step

Yes

Troubleshootin

g

6

Check if there is jammed by poor lubricating.

No

Next step

Yes

Replace

with

appropriate oil

7

If the failure is happened in winter time, check if

it is because of the wrong engine lubricant and

gearbox oil causes the big resistance of the

starting motor.

No

Check if other

systems

are

normal

Note: When this problem occurs, mainly inspect voltage, starter and ground system. In
modern sedan, lubricant has little effect on startup of the vehicle, so, basically, it needs
not to allow for lubricant problem, but the problem if the engine has too large self
resistance should be taken into consideration.

12.3 When Starting, Engine Can be Dragged to Rotate but Can not Start

with Success.

No.

Operating steps

Result

Follow up steps

Yes

Remove

the

failure displayed

1

Put the ignition switch to “ON”. Use a failure

diagnostic tester to check if any failure

information record exists.

No

Next step

Yes

8

2

Pull out cylinder distribution wire, connect

spark plug with the distance between electrode

of spark plug and engine body as 8-10mm, use

the starting motor to drag the engine to rotate,

and then check if blue-white high-voltage spark

occurs (disconnect all injection nozzles on the

engine).

No

Next step

Yes

Next step

3

Check if resistance value of ignition cable is

normal (can not exceed 16kΩ).

No

Repair, replace the

ignition cable.

Yes

Replace

4

Check ignition coil and ignition cable for burn

through, damage and crack.

No

Next step

Yes

Replace

5

Check if ignition cable is normal.

No

Next step

Yes

Next step

6

Check if the ignition coil is working normally.

No

Replace

Yes

Next step

7

Check if connectors of ignition coil and

ignition cable are connected properly.

No

Connect

the

connectors

properly

Yes

Next step

8

Put the ignition switch to “ON”. Check if fuel

pump relay and fuel pump can keep working for

a period of time.

No

Overhaul the fuel

pump circuit

Yes

Next step

9

Connect fuel manometer valve. Short 30# and

87# pins of fuel pump relay to make the fuel

pump run, and then check if fuel pressure is

around 400kPa.

No

13

Yes

12

10

Pull off the fuel distributing pipe and the fuel

injector; pull off the joints of fuel injector on the

harness one by one. And supply the voltage of

12 V from battery to fuel injector directly and

look if the fuel injector can inject normally.

No

Next step

11

Clean out the fuel injector and observe if it can Yes

Next step

work correctly.

No

Replace the fuel

injector

Yes

Replace fuel

12

Check if fuel is bad or moisture.

No

18

Yes

Next step

13

Check if the fuel pressure value is below 400

kPa.

No

17

Yes

Next step

14

Close the fuel manometer valve. Re-engage the

ignition switch to let the fuel pump run for a

period of time, and then check if fuel pressure

can be built up.

No

16

Yes

Check other part

15

Open the valve of fuel gauge and clamp the oil

return pipe by oil return baffle so that the oil can

not return. Check if the oil pressure occurs

immediately.

No

Repair or replace

the fuel pump

Yes

Repair or replace

oil intake pipe

16

Check if there is leakage or jam in oil intake

pipe.

No

Replace oil pump

Yes

Repair or replace

oil return pipe

17

Check if the oil return pipe is bended or

jammed.

No

Replace

fuel

pressure regulator

Yes

Repair or replace

the harness

18

Check if it is break or short circuit between 1#,

2# pins of crankshaft position sensor and 34#,

15# pins of ECU.

No

Next step

Yes

Repair

19

Check if the part of air intake system is leaking.

No

Next step

Yes

Repair or replace

20

Check if air flow meter works normally.

No

Next step

Yes

Next step

21

Check if the coolant temperature sensor is

working correctly.

No

Repair or replace

Yes

Remove

the

mechanical failure

22

Check if the reason for the failure on starting is

about mechanism, such as much cylinder

clearance, cylinder leaking, and so on.

No

Replace ECU

Note: When checking this problem, if all parts in electronic fuel injection system are
normal, consider if mechanical part of the engine works normally, or if cylinder
pressure is normal and if air leakage exists and so forth.

12.4 Warm Starting Difficulty

No.

Operating steps

Result

Follow up steps

Yes

Remove the failure

displayed

1

Put the ignition switch to “ON”. Use a special

diagnostic tester to check if any failure

information record exists.

No

Next step

Yes

Next step

2

Connect fuel manometer valve. Short 30# and 87#

pins of fuel pump relay to make the fuel pump

run, and then check if fuel pressure is around

400kPa.

No

9

Yes

Next step

3

Disconnect the connecting oil pipe and turn off the

ignition switch. Observe the voltage of fuel system

and look if it is around 300 kPa after an hour.

No

Repair

the

fuel

system

to avoid

leakage

Yes

Replace

fuel

pressure regulator

4

Put the connecting oil pipe through, use fuel tube

clamp to intercept the oil return pipe, meanwhile,

close the fuel manometer valve. Turn off the

ignition switch, after one hour, observe if pressure

of fuel system still can maintain at around 400kPa.

No

Next step

Yes

Replace the injector

and fuel pipe

5

Check if there is fuel leakage of fuel injector and

oil pipe.

No

Next step

Yes

Check

coolant

temperature

and

circuit

6

Pull out water temperature sensor joint and start

the engine. Observe if the engine can start with

success.

No

Next step

Yes

Next step

7

Connect an adaptor between ECU and harness,

check if a voltage around 5V is present on 39#,

17# pins, meanwhile, check if the resistance value

of water temperature sensor is within normal

scope.

No

Repair or replace

the harness

Yes

End

8

Replace ECU and perform warm start again;

observe if the engine can be started successfully.

No

Replace ECU

Yes

Next step

9

Check if there is jam or bending of fuel pipe and if

the pressure regulator valve of oil pump is

working correctly.

No

Repair or replace

Yes

Next step

10

Check if there is battery voltage between the plugs

of oil pump with multimeter.

No

Repair or replace

fuel pump relay and

wires

Yes

Next step

11

Try to replace the fuel pump and see if the system

can return to normal.

No

Replace fuel pump

Yes

Replace fuel pump

12

Check if the fuel pump is stopped up.

No

Replace ECU

Note: Warm starting difficulty is in connection with many systems, such as battery,
throttle body and water temperature sensor etc. as well as mechanical part of the engine,
such as valve sealing. Thermal expansion of engine under warm state may lead to rise of
engine resistance.

12.5 Engine Speed is Normal, but it is Difficult to Start at any Time

No.

Operating steps

Result

Follow up steps

Yes

Remove the failure

displayed

1

Put the ignition switch to “ON”. Use a special

diagnostic tester to check if any failure

information record exists.

No

Next step

Yes

Next step

2

Check the air cleaner and look if it is open.

No

Replace

Yes

Next step

3

After starting successfully, check if air intake

consumption of the engine at idle speed is

around 300Kg/h (remember to check if cylinder

pressure is normal).

No

Eliminate

the

failure of air intake

system leaking

4

Step on the throttle slightly and observe if it is

easy to be started easily.

Yes

Replace

the

electronic

throttle

body

Yes

Next step

5

Connect fuel manometer valve. Short 30#, 87#

pins of fuel pump relay to make the fuel pump

run, and then check if fuel pressure is around

400kPa.

No

9

Yes

8

6

Use a special joint to directly supply a 12V

voltage and intermittent ground wire from

battery to injector and check if the injector

works normally (work intermittently).

No

Next step

Yes

Next step

7

Clean out the fuel injector and look if it can

work correctly.

No

Replace

fuel

injector

Yes

Replace fuel

8

Replace fuel 8, and check if the fuel is

deteriorated or moisture.

No

14

Yes

Next step

9

Check if the fuel pressure value is below 300

kPa.

No

13

Yes

Next step

10

Close the fuel manometer valve. Re-engage the

ignition switch to let the fuel pump run for 3s,

and then check if fuel pressure can be built up.

No

12

Yes

Replace

fuel

pressure regulator

11

Open the valve of fuel gauge and clamp the oil

return pipe by oil return baffle so that the oil can

not return. Check if the oil pressure occurs

immediately.

No

Repair and replace

fuel injector and oil

pipe

Yes

Repair or replace

oil intake pipe

12

Check if there is leaking or jam in oil intake

pipe.

No

Replace oil pump

13

Check if the oil return pipe is bended or

jammed.

Yes

Repair or replace

oil return pipe

No

Replace

fuel

pressure regulator

Yes

Next step

14

When engine coolant is at low temperature, pull

out electronic throttle body on harness and

observe if engine revolution will rise.

No

Check

electronic

throttle body for

damage

Yes

Next step

15

Put the ignition switch to “ON”. Check if

voltage on the following pins of ECU is normal:

if it is a battery voltage around 12V on 12#, 14#,

15# pins; if the voltage between 51#, 53#, 3#,

61#, 80# pins and the wire is zero.

No

Check wires and

plugs

Yes

Next step

16

Check if ignition advance angle is normal.

No

Check

other

systems

Yes

Next step

17

Check if cylinder compression pressure of

engine is normal, if low, add a little engine oil

into each cylinder and re-measure if the cylinder

pressure is normal.

No

Troubleshooting

Yes

Repair or replace

18

If air cleaner or airflow sensor is choked.

No

Next step

Yes

Replace ECU

19

Check if the coolant temperature sensor is

working correctly.

No

Repair or replace

Note: Note if theft-proof system has started up. After theft-proof system has started up,
when starting the engine, the staring motor can run normally, but the engine can not
start; therefore, please note if this system can work normally.

12.6 Cold Starting Difficulty

No.

Operating steps

Result

Follow up steps

Yes

Remove the failure

displayed

1

Put the ignition switch to “ON”. Use a failure

diagnostic tester to check if any failure

information record exists.

No

Next step

Yes

Next step

2

Use a multimeter to check if the coolant

temperature sensor is normal. (A 2.8KΩ electric

resistance can also be connected in series between

39# and 17# pins of ECU to start the engine in

stead of the coolant temperature sensor. If the

engine can start, it indicates off normal of coolant

temperature sensor.)

No

Replace the sensor

Yes

Next step

3

Put the ignition switch to “ON”. Check if voltage

on the following pins of ECU is normal: if it is a

battery voltage around 12V on 12#, 14#, 15# pins;

if the voltage between 51#, 53#, 3#, 61#, 80# pins

and the wire is zero.

No

Check wires and

plugs

Yes

Next step

4

Check the air cleaner and look if it is open.

No

Replace

Yes

Next step

5

After starting successfully, check if air intake

consumption of the engine at idle speed is around

300Kg/h (remember to check if cylinder pressure

is normal).

No

Eliminate

the

leakage failure of

air intake system

Yes

Check

the

electronic throttle

6

Step on the throttle slightly and observe if it is

easy to be started easily.

No

Next step

Yes

Next step

7

When engine coolant is at low temperature, pull

out electronic throttle body joint on harness and

observe if engine revolution will rise.

No

Check the electric

throttle body

Yes

Next step

8

Connect fuel manometer valve. Let 86# pin of fuel

pump relay directly ground. Turn on ignition

switch to make fuel pump relay and fuel pump

work, and then check if fuel pressure is at around

400kPa.

No

12

Yes

11

9

Use a special joint to directly provide a 12V

electricity and ground wire from battery to injector

and check if the injector works normally.

No

Next step

Yes

Next step

10

Clean out the fuel injector and look if it can work

correctly.

No

Replace

fuel

injector

11

Check if fuel is deteroprated or moisture.

Yes

Replace fuel

No

17

Yes

Next step

12

Check if the fuel pressure value is below 300 kPa.

No

16

Yes

Next step

13

Close the fuel manometer valve. Re-engage the

ignition switch to let the fuel pump run for a

period of time, and then check if fuel pressure can

be built up.

No

15

Yes

Check fuel pressure

regulator and fuel

pump

14

Open the valve of fuel gauge and clamp the oil

return pipe by oil return baffle so that the oil can

not return. Check if the oil pressure occurs

immediately.

No

Repair and replace

fuel injector and oil

pipe

Yes

Repair or replace

oil intake pipe

15

Check if the oil intake pipe is leaky or jammed.

No

Replace oil pump

Yes

Repair or replace

oil return pipe

16

Check if the oil return pipe is bended or jammed.

No

Replace

fuel

pressure regulator

or fuel pump

Yes

Next step

17

Check if the pressure of cylinder is normal.

No

Troubleshooting

Yes

Repair

18

Check if the engine air intake system is leaky.

No

Next step

Yes

Repair or replace

19

If air cleaner or airflow sensor is choked.

No

Replace ECU

Note: The cold starting problem relates to more failure points, among which water
temperature sensor is comparatively important, because it is the major parameter for
determination of injection pulse-width when starting the engine. In case of a water
temperature sensor failure or it generates a false signal, the system can not judge the
temperature and starting difficulty may occur.

12.7 Unsteady Idle Speed at Any Time

Yes

Remove the failure

displayed

1

Put the ignition switch to “ON”. Use a failure

diagnostic tester to check if any failure

information record exists.

No

Next step

Yes

Repair or replace

the

electronic

throttle

2

Check if electronic throttle system of engine

works normally.

No

Next step

Yes

Check wires and

plugs

3

Turn on ignition switch, connect an adaptor

between ECU and harness, and then check if the

voltage between 17# and 42# pins of ECU,

between 39# and 17# pins of ECU (signal output

terminal of intake air temperature sensor and

coolant temperature sensor) as well as 64#, 65#,

66#, 67# pins of ECU (for control of DC motor) is

normal.

No

Next step

Yes

8

4

Let engine run at idle speed, spark out cylinder in

turn, and observe if engine revolution will fall and

fluctuate (cut fuel to injector).

No

Next step

Yes

Next step

5

Check the fuel injectors of each cylinder and look

if they are in right conditions.

No

Check fuel injector

and wires

Yes

Next step

6

Check if resistance value of ignition cable of each

cylinder is normal (can not exceed 16kΩ).

No

Replace

Yes

Maintain

7

Check if ignition system works normally.

No

Next step

Yes

Next step

8

Check if the spark plug is in right conditions.

No

Replace spark plug

Yes

Next step

9

Connect fuel manometer valve. Short 30# and 87#

pins of fuel pump relay to make the fuel pump

run, and then check if fuel pressure is around

400kPa.

No

13

Yes

12

10

Use a special joint to directly provide a 12V

power supply and intermittent ground wire signal

from battery to injector and check if the injector

can work intermittently.

No

Next step

Yes

Next step

11

Clean out the fuel injector and look if it can work

correctly.

No

Replace

fuel

injector

Yes

Replace fuel

12

Check if fuel is deteroprated or moisture.

No

18