Chery QQ6 (S21) / S12LHD. Manual — part 127

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②

Check the HECU with repetition device or checking device and determine if it has trouble

code.

† If with trouble code, firstly conduct the operation to delete the trouble code.
† If the trouble code can’t be deleted, implement with reference to section 2.4 “trouble

checklist of trouble code” (If the HU, motor or ECU has trouble, the inside of HECU
can’t conduct the air discharge and oil refill).

③

After the brake pedal is depressed, open the air discharge screw attached on the wheel brake

caliper or drum brake to discharge the internal air. It's required to 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.

④ 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

⑤

The operation in item

(air discharge) should be repeated for all wheels.

③

⑥ Measure the brake pedal travel. If not meet with the provisions, repeat the operations in item
④ (air discharge mode) and item ③ (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.

⑦

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.

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Annex I Malfunction Cases and Incorrect Repair Cases

1.

HECU Incorrect Repair Cases

① HECU replacement relating to ABS functioning noise

The HECU replacement case that deemed the noise of electromagnetic valve and motor as the
malfunction during the functioning of the ABS.

† During the functioning of ABS, the noise generated during the relieving or enhancing

of the braking pressure on various wheels is of normal functioning status. The noise
level will vary depending on the braking pressure applied on various wheels, other than
the product malfunction. Therefore, we should persuade the customers to understand
that.

† When the vehicle reaches 10km/h speed at the first time after vehicle start, the sensitive

customers may hear the noise at the time when the ECU diagnoses the motor drive,
which is also the normal functioning of the ABS.

② HECU replacement relating to EBD functioning noise

The HECU replacement case that deemed the clattering noise of rear wheels that other than
the ABS functioning noise during the braking as the malfunction.

† The ABS is also equipped with EBD function, which will effect the relieving of

braking pressure on the rear wheels when the rear wheels are locked ahead of the front
wheels. The noise generated during the above mentioned process is of normal
functioning status.

③ HECU replacement relating to braking off-tracking

HECU replacement case due to the vehicle braking off-tracking towards one side during the
braking.

† ABS is the braking assisted device that functioning in such manner that the ECU will

calculate the speed of various wheels in order to maintain the best braking force and
control stability during the braking. In the event of malfunction of the HECU, the ECU
will illuminate the warning lamp by means of the diagnosis. Therefore, in the event of
braking off-tracking without the illumination of ABS warning lamp, it’s necessary to
check other braking hydraulic devices.

† In the event of incorrect assembling of the braking hose, the braking off-tracking may

occur during the functioning of the ABS.

④ Replacement case that the ABS is functioning during barking at low speed (below 40km/h)

HECU and sensor replacement case that the ABS is always functioning during the braking at
low speed.

† During the braking at low speed, the ABS may also function depending on the road

conditions and braking pressure. If the ABS is always functioning at each time, it’s
necessary to check if the sensor air gap of various wheels is too large, if it has
interference with the gear ring, and if the tooth shape of the gear ring is damaged.

† Air gap adjustment method. For the improper air gap, after the determination of the

parts related to the problem, replace or grind the installation surface (junction portion)
of the sensor to the specified air gap; in the event of interference, place the thin gasket
onto the sensor installation surface so as to adjust to the specified air gap.

2. Incorrect Repair Cases for Wheel Speed Sensor

① Open-circuit and short-circuit related to sensor

The sensor replacement case without product checking when the ABS warning lamp is
illuminated and the trouble code of the vehicle is determined.

† The ABS trouble code is prepared based on the ABS products. Therefore, during the

open-circuit or short-circuit of the sensor, it’s necessary to conduct the problem
checking, such as confirm the connection status from the ECU to the wiring and
connectors of the sensor, measure the sensor resistance, and etc. During the
malfunction checking of sensor, it’s preferable to use the tetrastyle jack, which will
facilitate the confirmation of short-circuit problems such as the pinned wiring.

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† The union status of the sensor must be checked before the removal of the connectors

of connecting wiring (such as incomplete union, pin displacement, with impurity, and
etc.)After confirm that the sensor resistance and head are free of abnormalities,
centrally check the wiring and connectors.

② Notices for sensor checking

Case of sensor head line break arisen from over-pulling of sensor cable.

† When the connectors are removed during the checking of sensor, the instantaneous

pulling of cable under the condition that the sensor head is fixed will cause the falloff
of the internal cable of the sensor head to cause line break problem. Therefore, during
the checking of sensor, do not pull the cable with the force above the specified one.

† Sensor head cable: It may be damaged when applied with above 12kgf tension force;

Cable at connectors: it may be damaged when applied with above 4.5kgf tension force.

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Annex II ABS Basics

Will the braking distance be shortened when equipped with ABS?

† The testing data show that the braking distance will be shortened on most road

conditions (approximately 5%~20%). However, under some special road conditions
(such as snowy road, non-asphalt road and rough road), the braking distance will be
lengthened. However, the steering stability can be guaranteed.

What’s the main objective of ABS?

† The main objective of ABS is to prevent the wheels to be locked, which has following

effects:

① Maintain the vehicle stability on roads during the braking
② Capable of controlling the vehicle driving direction during braking in order to avoid the
occurrence of the collision.
③ Maintain the best braking pressure, disregarding the driving skills of the driver.

Why is the ABS warming lamp illuminated?

† After the driver starts the vehicle, the warning lamp will be off when the automatic

diagnosis of ABS ECU shows no trouble. If the warning lamp is illuminated during
driving or the warning lamp is always on, it indicates the trouble of ABS. Please drive
your vehicle to the designated service station for checking of ABS as soon as possible.
However, when the warning lamp is illuminated that indicates the ABS trouble, the
brake system still has the basic braking capability.

Will there be free of accident when equipped with ABS?

† ABS is the one device capable of increasing the driving safety, rather than the device

used to avoid the accidents arising from the driving mistake or variation of traffic
conditions. Therefore, insist on the safe driving all along rather than the excessive
reliance on the ABS.

The vehicle will lean to one side during braking on the one-side-slippery road, is this
phenomenon caused by ABS?

† This phenomenon is resulted from the different friction coefficients between the left

and right wheels on the roads. Under such condition, the ABS will exert the special
effects on the stability of the vehicle body. However, even under such condition, make
sure to operate the steering wheel with car in order to avoid the occurrence of accidents.

The vehicle will present the slippery phenomenon before braking during the turning on the
slippery road, will the ABS function effectively when the brake pedal is depressed at that time?

† The ABS will function effectively to provide certain help depending on the vehicle

speed. However, under most conditions, the outward cornering force is really big due
to the vehicle inertia and therefore the body correction will have limit even the ABS is
functioning.

† Generally, the tires will be applied with two kinds of forces during cornering: One is

the force required by driving and braking; another is the force required for vehicle
steering and stability maintaining. In fact, the driving, braking and steering of the
vehicle are completed though the coordination of above two forces and the two forces
are in reverse ratio. Therefore, during the braking at cornering, the braking force will
be increased and the force required for steering and stability maintaining will be
reduced. The vehicles equipped with ABS will best coordinate these two forces. For the
vehicles without the ABS, the steering performance and the stability are really weak as
these two forces are not in good coordination.

† However, under the condition that the above two forces are really small (such as: off-

tracking due to excessive speed during the vehicle skid), the force for body correction
is really small. Therefore, the ABS will not exert the effects. In conclusion,
deceleration in advance and safe cornering is the best method.