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Engine JAC HFC4DA1-2C. Manual - part 139

ABS

ABS Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake System

System

- 77 -

Instruction

Instruction and

and

and Operation

Operation

Fault

Fault diagnosis

diagnosis

diagnosis procedures

procedures

procedures for

for

for ABS

ABS

ABS with

with

with EBD

EBD

S/N

Operation

Drive the vehicle into repair shop.

Go to the next step.

Customer problem analysis

Go to the next step.

Read diagnostic trouble code (DTC).

With DTC

Go to Step 4

No DTC

Go to Step 9

Record DTC and clear fault memory.

Go to the next step.

Verify and reproduce fault: Simulation of fault occurrence status.
Read DTC again.

With DTC

Current DTC. Go to Step 8

No DTC

History DTC. Go to Step 6

Is it relevant to fault symptom?

Yes

Intermittent fault. Go to Step 7

Eliminated fault. Go to Step 9

Perform fault simulation again.

Go to the next step.

Perform troubleshooting based on DTC list. Go to Step 10.

Go to the next step.

Perform troubleshooting based on fault symptom list.

Go to the next step.

Ensure the fault is eliminated.

Go to the next step.

Prevention of recurrence.

Go to the next step.

End

ABS

ABS Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake System

System

Diagnosis

Diagnosis and

and

and Testing

Testing

Diagnosis

Preliminary inspection

Inspect those easily accessible components that may
lead to ABS system fault. Faults can be determined
quickly through visual and appearance inspection, in no
need of further diagnosis.

(a)

Ensure the vehicle is equipped with wheels and
tires of recommended size. Coaxial tires should be
of the same pattern and tread depth.

(b) Check the hydraulic governor, brake line and

connector for leak.

(c)

Check ABS fuses - 10A, 25A and 40A. Only the
fuses of correct rating should be applied.

(d) Ensure the battery is fully charged.

(e)

Check battery connection for corrosion or terminal
looseness.

(f)

Perform visual and appearance inspection for
electrical components listed below:
①

Check ABS component harnesses and pins for
wrong connection, damage due to clamping or
cutting.

②

Check whether the harnesses are arranged
close to high voltage or heavy current devices,
such as:

�

High voltage ignition component;

�

Motor and generator;

�

Stereo amplifier optional equipped.

IMPORTANT: High voltage or heavy current
devices are likely to make induced noise generated
in circuit interfering normal operation of circuit.
③

Check connectors of ABS system relevant
components for poor connection or check pins
for incomplete insertion into connector shells.

④

ABS

components

are

sensitive

electromagnetic interference (EMI). If any
intermittent fault is suspicious, please check
whether

the

optional

equipped

anti-theft

devices, lamps or mobile phones are properly

installed.

(g) ABS is a kind of active safety system, which

mainly functions to maintain vehicle’s steerability
and driving stability in the course of braking and to
minimize the braking distance through obtaining
the maximum deceleration. With the adoption of
ABS for braking, there is little but uniform tire
wear, for adhesion applied between tire and road
surface is realized based on adhesion coefficient
limit. However, ABS is unable to avoid skidding of
vehicle completely if the vehicle speed at turning
exceeds the limit or the vehicle is running at high
speed on slippery road.

(h) ABS sound

When the vehicle is running for about 15Km/h
after the start of engine, there is a short buzz
generated in the engine compartment, which is the
sound of ABS self-checking but not abnormal noise.
Kinds of sound in the course of ABS functioning
include:

�

Operation sound of motor, solenoid valve and

reflux pump inside ABS hydraulic unit;

�

Sound generated from vibration of brake

pedal;

�

Suspension knock sound arisen by braking

during ABS operation.

�

Excessive noise during system self-checking

or ABS functioning may be caused by:

�

Looseness of ABS fixation;

�

Looseness of ABS bracket;

�

Damage or missing of plastic washers on ABS

bracket;

�

Looseness of brake relevant connection or

fixation;

�

Brake

line

connection

direction

nonconforming to delivery status;

�

Air bubbles in brake line.

�

ABS

ABS Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake System

System

- 79 -

ABS

ABS Operating

Operating

Operating principle

principle

principle::::

ABS shall enter antilock brake mode once wheel
skidding is detected during braking. In the course of
antilock braking, the hydraulic circuit pressure of each
wheel is under control to avoid wheel skidding. Each
wheel is equipped with individual hydraulic line and
valve. ABS is able to reduce, maintain or increase the
hydraulic pressure of each wheel braking. However, it is
unable to increase the hydraulic pressure to a certain
level that exceeds the pressure delivered by the master
cylinder during braking. In the course of antilock
braking, a series of quick vibration of brake pedal can
be felt. The pedal vibration shall appear during antilock
braking and disappear during conventional braking or
after complete stop of vehicle. Operation noise can be
heard due to quick cycle use of solenoid valve. When
antilock braking is applied on dry road, intermittent
sharp noise shall generate right before wheel skidding.
Those noises and pedal vibration under antilock braking
are normal symptoms. Operation of brake pedal during
conventional braking should be the same as that of
vehicle without ABS system. Maintain balance pedal
force can both ensure the vehicle stability and the
shortest stopping distance.

Pressure maintenance

Once wheel skidding is detected, ABS control module
shall close the oil inlet valve and then make the oil
outlet valve in the hydraulic assembly closed to isolate
the system, which can keep the brake pressure stable

and avoid boosting or reducing of hydraulic pressure.

Pressure reducing

Under the pressure maintenance mode, wheel skidding
can still be detected by ABS control module to reduce
the affected wheel pressure. Keep the oil inlet valve
closed and oil outlet valve open. The redundant
fluid/pressure shall be temporarily stored into the
accumulator in hydraulic assembly until the pump motor
is able to return the brake fluid into oil reservoir of
master cylinder.

Pressure boosting

If decrease of wheel skidding is detected by ABS
control module under pressure maintenance or pressure
reducing mode, the ABS control module shall boost the
affected wheel pressure through applying the pressure of
master cylinder. Keep the oil inlet valve open and oil
outlet valve closed. Pressure from master cylinder shall
be partly or fully applied onto wheels.

Operating procedures of ABS

During vehicle running, each wheel speed sensor shall
produce a voltage signal in proportion to wheel speed.
ABS control module shall make judgment based on the
received wheel speed data; if more than one wheels
decelerate rapidly (compared with reference vehicle
speed), it is determined as skidding. ABS control
module shall activate the module as required to control
over the brake pressure of each wheel to achieve
optimization.

Schematic

Schematic Diagram

Diagram

Diagram of

of ABS

ABS

ABS Hydraulic

Hydraulic

Hydraulic System

System

System::::

Schematic Diagram of ABS Hydraulic System

1. Master cylinder

2. Oil inlet valve (LF)

3. Oil outlet valve (LF)

4. Oil inlet valve (RR)

5. Oil outlet valve

(RR)

6. Damper

7. Oil return pump 8. Accumulator

9. Oil inlet valve (RF)

10. Oil outlet valve (RF)

11. Oil

inlet valve (LR)

12. Oil outlet valve (LR)

ABS

ABS Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake System

System

- 80 -

Diagnosis

Diagnosis and

and

and Testing

Testing

Diagnosis

Checking instrument warning lamp

(a) Release the parking brake lever.

(b) Check the warning lamp.

With the ignition switch turned on, check if ABS
and EBD warning lamps is lit and then go out in a
few seconds.

Remarks:

�

With the parking brake applied, the EBD

warning lamp shall be lit (details based on
actual conditions).

�

As for some vehicle models, EBD warning
lamp shall be lit if brake fluid level is too low
(details based on actual conditions).

�

In case of abnormal operation of warning
lamps, please perform troubleshooting for
ABS or EBD warning lamp circuit.

S/N

Operation Sequence

EBD Warning

Lamp

ABS Warning

Lamp

With the ignition switch turned on, ABS and EBD warning lamps should be lit.

If the system is normal, the warning lamps shall go out in about 3 seconds.

The system is normal after self-checking.

OFF

① There is current DTC not removed in ABS.

ABS stops operation but EBD is still operating.

For example: Only one wheel speed sensor failed.
② There are current DTCs of wheel speed sensor and reflux pump in ABS.

With the vehicle speed below 12Km/h, ABS warning lamp is lit but ABS stops operation.

With the vehicle speed no below 12Km/h, ABS warning lamp goes out after no fault is
detected and the current DTC becomes the history DTC.

OFF

① Diagnosis on ABS by diagnostic instrument.

With the vehicle speed below 10Km/h, all diagnoses of ABS function normally.

With the vehicle speed over 10Km/h, two lamps go out once the system is detected to be

normal and diagnosis is cut off automatically if the ABS controls normally.

②EBD failure.

Both ABS and EBD stop operation.

For example: Over three wheel speed sensors failed.

Too low brake fluid level or unreleased parking brake lever (details based on actual
conditions).

Both ABS and EBD electrical components operate normally.

OFF

Content .. 137 138 139 140 ..