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

No

No

No

No

Is it normal?

Yes

Yes

Yes

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

st

vacuum;

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

st

vacuum cut-off;

F : Applicable for 2

nd

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

On

Off

On

Off

On

Off

On

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

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

N.G

Abnormal

functioning,

separate

repetition required

Case 4

Not functioning

O.K

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

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.