Chery QQ6 (S21) / S12LHD. Manual - part 126

Page 29 of 38

Table 5

Trouble

Evidence

Without diagnosis code output (communication failure with trouble diagnosis
instrument)

Possible Cause

● Problem of diagnosis instrument
● Burn of fuse
● Broken of diagnosis line or loosening of connector
● ECU damage of ABS

Troubleshooting

Flow

Is it normal?

Yes

Check and replace

diagnosis instrument

Check and replace ABS

ECU fuse

Check

and

replace

wiring of harness side
pin 7

Correctly install the

connector

Confirm

the

connection

between

the

diagnosis

instrument connector and
vehicle diagnosis connector

Is fuse (10A)

normal?

Confirm if the ABS ECU
fuse (10A) in the fuse box
is burnt?

Is it powered?

With

communications?

After the trouble number is
determined, take measures based
on

the

troubleshooting

for

various trouble numbers.

Correctly connect the harness

side connector and confirm
the communications.

After the harness side connector is

removed, confirm if it’s powered
between the harness side pin 7 and

vehicle diagnosis connector pin 7

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IV. Air Discharge and Oil Refill

1. Regular Operation Procedure

The regular operation procedure of air discharge and oil refill is shown in the figure, of which:

A :    Move the vacuum device and brake oil refill device;
B :    Start after connected with vacuum and brake oil refill device and SDL;
C :    Drive normal close electromagnetic valve and apply the 1

vacuum;

D : Excessive leakage test;
E : Minor leakage test after the 1

vacuum cut-off;

F : Applicable for 2

vacuum and drive motor;

G :    After the oil refill and maintaining of pressurization on the brake oil, relieve the brake oil pressure, stop
the normal close electromagnetic valve and motor, and adjust the brake oil level;
H :    Disconnect the vacuum device and brake liquid refiller;
I :    Screw on the oil reservoir lid/disconnect the SDL;
J :    Transfer to next step.

2. Checking Device

① The vacuum supplied to the oil reservoir should be as lower as possible, provided that the oil gun must
supply at least below 1mm Hg vacuum.

②   Confirm  if  the  air  discharge  screw  portion  of  the  rear  wheel  hydraulic  device  (drum  brake  or  brake
caliper)  forms  the  vacuum  within  the  specified  period.  (It  should  be  below  5~10mm  Hg  after  connected
with vacuum for 20~25s).

③ Confirm if the working voltage supplied to the HECU is at specified 10~12V.

④ Confirm the circulation time (C/T). Confirm the working time setting of the electromagnetic valve
meets with the specified value.

† C/T< 90: Run the electromagnetic valve continually;
† 90≤C/T≥180: Start the electromagnetic valve for 2s and stop the electromagnetic valve for 2s.

continually repeat above cycles;

† C/T>180: The total running period setting of the electromagnetic valve is below 90s.

3. Notices for Air Discharge and Oil Refill

Add brake fluid

Normal

Close Valve

Motor

Vacuum

Procedures

Off

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①    During the refilling of brake oil, if the refilling pressure is not maintained for certain period or
above,  the  oil  level  within  the  oil  reservoir  will  lower  at  the  finish  of  the  refilling.  Therefore,  it’s
required to refill more brake oil or maintain the refilling pressure for certain period.

②   The time period marked in the regular operations refers to the general circulation period.

③  The inside  of after-service HECU is at  moisture status,  therefore, it  may  not  conduct the air
discharge  mode  operation  (see  succeeding  item  5⑥  for  the  definition  of  air  discharge  mode)  but
directly  conduct  the  air  discharge  operation  on  all  wheels  (However,  in  order  to  meet  with  the
performance and pedal comfort, it’s preferable to conduct the air discharge mode operation).

④   During  the  air  discharge  mode  operation,  the  voltage  supplied  to  HECU  is  preferably  at
10~12V.  However,  during the  use of checking  devices, it will be OK  to  use  the  vehicle amounted
battery. (The repeated air discharge mode operation with high voltage may damage the coil of ECU
components).

4. Determination Method for Vehicles with Air Discharge Trouble

Leakage test

Differentiation

Category

ECU functioning or

not

Excessive

leakage

Minor

leakage

Note

Case 1

Normal functioning

O.K

Normal functioning, no separate
repetition required

Case 2

Normal functioning

O.K

N.G

Abnormal

functioning,

separate

repetition required

Case 3

Normal functioning

N.G

Abnormal

functioning,

separate

repetition required

Case 4

Not functioning

O.K

Abnormal

functioning,

separate

repetition required

Case 5

Not functioning

O.K

N.G

Abnormal

functioning,

separate

repetition required

Case 6

Not functioning

N.G

Abnormal

functioning,

separate

repetition required

† Case 1 : The status at finish of normal functioning.
† Case 2 : The status that the connection of brake (HECU hole portion/brake pipe/brake

hose) is poor and therefore needs rework.

† Case 3 : The status same with Case 2, but it may cause the status incapable of

repetition when the leakage is really severe.

† Case 4 : Internal circuit air discharge trouble of HECU. It's the status necessary for

repetition as the ABS may cause the sponge phenomenon after functioning for one time.

† Case 5 : The comprehensive trouble of Case 2 and Case 4. The status necessary for

repetition.

† Case 6: The status similar to Case 5, but it may cause the status incapable of repetition

when the leakage is really severe.

5. Measures in Event of Troubles during Air Discharge and Oil Refill (for internal dry
status of brake system)

①

Implementation of trouble determination. It’s required to determine the connection portions of

all components from the general pump to the wheel branch pump: HECU hole portion, connection
portion of brake pipe, connection portion of brake hose, brake caliper and the air discharge screw
portion of brake, and etc.

②

After the determination of the trouble, re-assemble in accordance with the provisions in order

to avoid the further occurrence of leakage.

③   Connect  the  repetition  device  to  the  25-pin  connector  of  the  ECU  or  connect  the  checking
device  to  the  line  K  (pin  7).  Use  the  specific  wiring  to  connect  to  the  connectors.  During  the
connection to  line  K (pin 7), make  the  vehicle  at power on  or start status.  The  oil reservoir  of the
general pump is connected with the device for continual supply of brake oil or it’s required that the
oil reservoir should have enough oil during the supply of brake oil.

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④.    Check the HECU with repetition device or checking device and determine the existence of
trouble code. If with trouble code, firstly conduct the operation for deletion of the trouble code (if
the  trouble  in  above  item  ①  is  not  determined,  it’s  necessary  to  determine  the  existence  of
trouble  code).  When  the  trouble  code  can’t  be  deleted,  operate  with  reference  to  the  Trouble
Checklist  of  Trouble  Code  in  section  2.4  (In  case  of  trouble  of  HU,  motor  and  ECU,  the  air
discharge and oil refill can’t be conducted at the inside of the HECU).

⑤   After the brake pedal is depressed, open the air discharge screw attached onto the wheel brake
caliper  or  drum brake  to discharge the air.  Conduct this  operation  on all  wheels, till that the brake
oil discharged from the air discharge screw is free of air and the brake pedal is properly rigid. Refer
to  the  operation  in  item  ⑩  in  using  the  repetition  device  capable  of  vacuum  formation  and
refilling of brake liquid.

⑥  Conduct  the  air  discharge  mode by  means of the repetition device or the checking  device. If
there  has  no  reaction  force  when  the  brake  pedal  is  depressed,  then  repeat  the  operation  of  pedal
depressing and pedal releasing, till the air discharge mode is completed (air discharge mode: repeat
the  start  in  2s  interval,  stop  the  normal  close  valve  of  HECU  for  1min,  and  continually  drive  the
motor.  The  repeated  operation  of  pedal  depressing  and  pedal  releasing  is  conducted  within  the
period of normal close electromagnetic valve and motor drive).

⑦

The operation in item

(air discharge) should be repeated for all wheels.

⑤

⑧    Measure the brake pedal travel. If not meet with the provisions, repeat the operations in item
⑥  (air  discharge  mode)  and  item  ⑤  (air  discharge).  If  the  brake  pedal  travel  doesn't  meet  with
the  provisions  after  the  air  discharge  mode  and  air  discharge  are  repeated  for  above  10  times,
replace with after-service HECU (wet type) and then repeat the operations from the beginning.

⑨

Connect the repetition device and checking device to the HECU and again determine the

existence of trouble code. If with trouble code, delete the trouble code and then disconnect the
repetition device or checking device.

⑩

During the use of other repetition devices (the equipment capable of vacuum formation and

liquid refilling), the implementation method is as follows:

† Conduct in accordance with the contents in above item ①～④;
† When the vacuum pump is sufficiently driving for approximate 60s, the inside of brake

system will form the vacuum status.

C Start the operation of air discharge mode in above item ⑥ 10s before the vacuum cut-off.
C Without the repeated operations of pedal depressing and pedal releasing.

† Conduct the brake liquid refilling operation (above 7bar/100Psi) for above 20s at the same

time of vacuum cut-off.

† Complete the brake liquid refill and air discharge mode.
† Conduct the operation based on the contents in above item ⑧～⑨.

6. Measures in Event of Trouble during Checking and ABS Functioning Test (for internal
wet status of brake system)

① Connect the repetition device or checking device. The following conditions must be
guaranteed:

† Use the specific wiring while connecting to the 25-pin connector of ECU.
† The vehicle should be at power on status or start status while connecting to line K (pin

7).

† The oil reservoir of the general pump is connected with the device for continual supply

of brake oil or it’s required that the oil reservoir should have enough oil during the
supply of brake liquid.

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