JAC HFC4DA1-2C engine. Instruction — part 36

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

84

DTC

DTC

DTC

DTC List

List

List

List

Attention:

Attention:

Attention:

Attention:

Please turn off the ignition switch before removal of parts.

Note:

Note:

Note:

Note:

Please use the diagnostic instrument to read DTC.

If no fault is detected during the detection of components, ABS hydraulic governor with ECU and its ground
point/power line should be inspected.

When more than two DTC is in memory, the fault relevant DTC and circuits should be inspected at first.

DTC

DTC

DTC

DTC list

list

list

list

DTC

Detection Item

Possible Failure Areas

C0035

Left front wheel speed sensor circuit fault

Left front wheel speed sensor circuit, gear ring or sensor itself

C0040

Right front wheel speed sensor circuit fault

Right front wheel speed sensor circuit, gear ring or sensor itself

C0045

Left rear wheel speed sensor circuit fault

Left rear wheel speed sensor circuit, gear ring or sensor itself

C0050

Right rear wheel speed sensor circuit fault

Right rear wheel speed sensor circuit, gear ring or sensor itself

C0060

Left front oil outlet valve circuit fault of hydraulic
governor

ABS hydraulic governor with ECU

C0065

Left front oil inlet valve circuit fault of hydraulic
governor

ABS hydraulic governor with ECU

C0070

Right front oil outlet valve circuit fault of
hydraulic governor

ABS hydraulic governor with ECU

C0075

Right front oil inlet valve circuit fault of hydraulic
governor

ABS hydraulic governor with ECU

C0080

Left rear oil outlet valve circuit fault of hydraulic
governor

ABS hydraulic governor with ECU

C0085

Left rear oil inlet valve circuit fault of hydraulic
governor

ABS hydraulic governor with ECU

C0090

Right rear oil outlet valve circuit fault of hydraulic
governor

ABS hydraulic governor with ECU

C0095

Right rear oil inlet valve circuit fault of hydraulic
governor

ABS hydraulic governor with ECU

C0110

Reflux pump motor fault: Operation or stopping
failed

ABS hydraulic governor with ECU

Ground/power supply for ABS hydraulic governor with ECU

C0121

Solenoid valve relay circuit fault

ABS hydraulic governor with ECU

Ground/power supply for ABS hydraulic governor with ECU

C0161

ABS brake lamp switch circuit fault

Brake lamp switch and its circuit

ABS hydraulic governor with ECU and its circuit

C0245

General fault of wheel speed sensor

Wheel speed sensor circuit, gear ring or sensor itself

C0550

ABS ECU fault

Battery

Ground/power supply for ABS hydraulic governor with ECU

ABS hydraulic governor with ECU

C0800

Voltage out of range

Battery

Charging system

Power/ground circuit

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

85

Diagnosis

Diagnosis

Diagnosis

Diagnosis and

and

and

and Testing

Testing

Testing

Testing

Fault symptom table

If fault occurs without fault memory during DTC reading, please check relevant circuits of each fault symptom in
order listed below and by referring to relevant fault diagnosis content.

Attention:

Attention:

Attention:

Attention:

Before maintenance of ABS, please ensure the conventional brake system operates normally.

When the replacement of ABS hydraulic governor with ECU, sensors or other components is necessary, please turn
off the ignition switch firstly.

Fault Symptom

Check Areas

ABS failed to operate

1. Check if ABS and EBD warning lamps are lit;

2. Read DTC and check for any fault;

3. Check power UZ circuit of ignition switch;

4. Check brake line for any leak.

ABS poor effect

1. Read DTC and check for any fault;

2. Check brake line for any leak;

3. Apply diagnostic instrument to read “occupied state of hydraulic governor”;

4. Check the power supply state of battery;

5. Ensure the mounting bracket is fixed at normal state (at this time the driving comfort

may decrease).

Abnormal ABS and EBD
warning lamps

1. Read DTC and check for any fault;

2. Check the circuits of ABS and EBD warning lamps;

3. Check power UZ circuit of ignition switch;

4. Check the power supply state of battery;

Diagnostic

instrument

failed to read DTC

1. Check if ABS and EBD warning lamps are lit;

2. Check the power line and ground cable of ABS hydraulic governor with ECU;

3. Check power UZ circuit of ignition switch;

4. Check the power supply state of battery;

5. Check the DIAGK cable of ABS hydraulic governor with ECU;

6. Check the diagnostic instrument for reliable connection.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

86

Diagnosis

Diagnosis

Diagnosis

Diagnosis and

and

and

and Testing

Testing

Testing

Testing

Intermittent fault diagnosis table

Note: In case one of the following conditions occurs, there is intermittent fault.

Fault does not always occur;

It may probably occur again;

There is history DTC but no current DTC.

Inspection

Operation

Preliminary inspection

1. Perform “preliminary inspection” at first;

2. Collect information relevant to the arising of intermittent fault from the customer, such

as:

1) Driving conditions (vehicle speed, brake, warning lamps and road condition) when the

fault occurs.

2) Does the fault occur during the application of electrical equipments added by service

shop?

3) Has the battery status been checked?

4) Have the wheel speed sensor harnesses and gear rings been checked?

Detection by diagnostic
instrument

Detection procedures:

1. Operate the suspicious ABS component harnesses and connectors and observe the data

stream of measured circuit on the diagnostic instrument. If the reading of diagnostic
instrument fluctuates during this operation, please check circuits for loose connection.

2. Perform vehicle road test under occurrence of intermittent fault and ask an assistant to

observe the suspicious operating parameters on the diagnostic instrument.

3. Capture and store data by snapshot once fault occurs. The stored data can be displayed

at lower speed to facilitate diagnosis. Oscilloscope can also be applied for signal
detection.

4. Apply the “Component Test” function of diagnostic instrument to control the

suspicious ABS components to test their operation.

Warning lamps

The following conditions may lead to intermittent illumination of warning lamps without
DTC set.

1. Warning indicator circuit is shorted to ground intermittently.

2. Ground points of ABS hydraulic governor with ECU or instruments become loose.

3. Battery voltage is a little lower or unstable under stationary state of vehicle.

Wheel speed sensor

1. Visually inspect wheel speed sensors and gear rings for looseness, damage, foreign

matters or improper installation. Please replace any damaged component, remove any
foreign matter or fix any loosened component accordingly.

2. Check the wheel speed sensor for proper wiring and ensure the harnesses of wheel

speed sensor are not interfered by mechanical components.

3. Monitor the data display of wheel speed sensor on diagnostic instrument with

assistance and at the same time perform road test to check if any wheel speed sensor in
abnormal speed range is displayed.

Additional testing

1. Check electrical equipments added by service shop such as mobile phones, anti-theft

warning devices, lamps, radio equipments, stereo amplifiers and so on for correct
installation.

2. Check if any electromagnetic interference (EMI) is caused by failed components (such

as relays or solenoid valves) with power on.

3. Power-on test for motors and solenoid valves.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

87

Diagnosis

Diagnosis

Diagnosis

Diagnosis and

and

and

and Testing

Testing

Testing

Testing

1.

Wheel speed sensor fault (C0035, C0040, C0045, C0050, and C0245): Wheel speed sensors are applied to detect
the wheel speed and transmit relevant signals to ABS ECU. These signals are used for controlling ABS operation.
Each wheel is equipped with a sensor and with a 48-tooth gear ring mounted on its axle shaft. This vehicle model
mainly adopts the active wheel speed sensors that are activated by 12V DC power voltage supplied by ABS ECU.
Wheel speed sensor adopts Hall Effect with nearly constant output amplitude and square wave of 50% duty cycle,
with low voltage of 0.5V and high voltage of 1V; its frequency increases with the increase of vehicle speed. ABS
ECU shall calculate the wheel speed based on this frequency.

Output signals:

Output signals:

Output signals: 0.44~0.63 (low voltage), 0.89~1.26 (high voltage)

Output signals: 0.44~0.63 (low voltage), 0.89~1.26 (high voltage)

U

n

d

er

st

at

io

n

ary

or

Low speed

High speed

U

n

d

er

ru

n

n

in

g

st

at

e

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

88

DTC

Detection Condition

Set Condition

Possible Faulty Areas

C0035

C0040

C0045

C0050

With

the

ignition

switch turned on

All conditions

1) Monitor if the power voltage of sensor is too low;

2) Monitor if the power wire and signal wire of sensor is

normal.

1. Wheel speed sensor bodies

2. Wrong connection of wheel

speed sensors

3. Wheel speed sensor signals

being interfered

4. Too large clearance between

wheel speed sensor and gear
ring (displacement caused by
vibration)

5. Corrosion

of

wheel

speed

sensors and supports

6. Gear ring fault (dirty, tooth

damage)

7. Tires: size, pressure, pattern

and tread depth

8. Connectors

flawed,

contaminated or affected with
damp

9. Loosened or fractured wheel

speed

sensors/connecting

wires/connectors

10. Sensor

circuit

shorted

to

ground

11.Damaged insulation of sensor

cables

Wheel

speed

monitoring

a．Reference vehicle

speed within 0 ～
100Km/h

1) At least one wheel speed above the reference vehicle

speed of 12km/h over 8s (72s is required in case of
wheel skidding;

2) Speed difference between wheels on the same side

(such as left front and left rear wheels) over 6Km/h,
or speed difference between wheels on the same axle
(such as left front and right front wheels) when
turning over 10Km/h, or speed difference between
diagonal wheels (such as left front and right rear
wheels) when turning over 14Km/h.

Wheel speed
monitoring

b. Reference vehicle

speed ＞100Km/h

Speed difference between wheels on the same side over

6% of the reference speed, or speed difference between
wheels on the same axle when turning over 6%+4Km/h of
the reference speed, or speed difference between diagonal
wheels when turning over 6%+8Km/h of the reference
speed.

Long time monitoring
of signal interference

1) In case signals of one or two wheel speed sensors fail,

fault shall be detected in 20s (with brake pedal
depressed) or 5s (without brake pedal depressed).

2) In case signals of three or four wheel speed sensors

fail, fault shall be detected in 1s.

Monitoring of wheel
speed difference

Perform monitoring when vehicle speed over 20Km/h

and 20s (or 80s in case of wheel skidding) is needed
for fault confirmation:

1) If the vehicle speed is within 20Km/h～100Km/h, the

speed difference between the fastest and slowest
wheels shall exceed 6%;

2) If the vehicle speed is over 100Km/h, the speed

difference between the fastest and slowest wheels
shall exceed 6Km/h;

3) During vehicle turning, vehicle speed difference

range shall increase by 4Km/h.

Gear ring monitoring

For example: Missing
teeth

With vehicle speed of 10～ 60Km/h and no operation of

ABS, missing pulse number per rotation of wheel is
displayed for over 10 times.

Dynamic monitoring

If the vehicle speed is over 43Km/h, no wheel speed

signal is received within 10～20ms in interval of 60ms.

Monitoring

of

fast

starting speed

(only for wheel speed
sensors

of

driving

wheels)

1) With vehicle speed over 12Km/h, the speed of one or

two wheels is below 2.75Km/h;

2) If the speed of one wheel decreases below 2.75Km/h

with running speed of v1 (over 12Km/h), the fault can
be detected when the vehicle speed increases by
18Km/h, viz. speed increase up to v1+18.

Monitoring

of

slow

starting speed

If the speed of two wheels is over 12Km/h and the speed

of the other one or two wheels is below 5Km/h, 20s is
needed for fault confirmation.

With

the

ignition

switch turned on

All conditions

If one of the following faults appears for over 200ms:

1. Sensor wiring circuit open, open to ground or power

supply

2. Loosened sensor connectors

The current of wheel speed sensor is out of range:

Current ＜1.1mA or ＞39mA

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

89

Occurrence of fault shall give rise to the following operation:

Braking Strategy

Failure Protection

Relevant wheels cannot be controlled any more because correct
wheel speed sensor signals cannot be obtained. When fault occurs,
ABS shall make the pressure of front wheels increase and that of
rear wheels decrease until the ignition switch is turned off.

�

The system shall be converted to EBD
emergency control mode.

�

ABS warning lamp shall be lit.

If failure of one or two wheel speed sensors is detected in ABS
control process, the system shall be converted to EBD emergency
control mode until this control process is finished.

�

The system shall be converted to EBD
emergency control mode.

If failure of three or four wheel speed sensors is detected,

�

Brake system shall enter the conventional
braking mode.

�

ABS and EBD warning lamps shall be lit.

Remarks: If the ignition switch is turned on after fault removal, the warning lamp shall go out only when the vehicle
speed exceeds 12Km/h.

Troubleshooting

Troubleshooting

Troubleshooting

Troubleshooting procedures

procedures

procedures

procedures

S/N

Operating Step

Operation

Detection
Result

Next Step

1

Fault confirmation

(a) Connect the diagnostic instrument, read and record

DTC.

(b) Clear of DTC: Apply diagnostic instrument to clear

DTC as per prompt of the instrument.

Remarks: DTC cannot be cleared if the battery is
removed.

Please ensure normal voltage of battery before

removing fault.

(c) Conduct fault simulation to see if the fault reoccurs.

Yes

If it is current fault, please go
to Step 3

No

If it is history fault, please go
to the next step.

2

Intermittent

fault

diagnosis

(a) Check wiring between ABS hydraulic governor with

ECU and wheel speed sensors and relevant connectors.
Please refer to “04-Inspection before diagnosis” for
inspection methods and procedures.

(b) Check the free travel of hub bearing.

Normal value of free travel of hub bearing: 0mm

Is the problem solved?

Yes

Go to Step 11

No

Go to Step 4

3

Appearance
inspection

(a) Check wiring between ABS hydraulic governor with

ECU and wheel speed sensors and relevant connectors.
Please replace it when necessary.

(b) Check tires:

1. Check every tire size and perform replacement when

necessary.

2. Check tires and wheel hubs for any damage; perform

repair or replacement when necessary.

3. Check tire pressure and make adjustment when

necessary.

4. Check tire pattern for any abnormal wear (eccentric

wear, excess wear, uneven wear and depth); perform
replacement or make tire balance, four-wheel alignment
and girder correction when necessary.

Is the problem solved?

Yes

Go to Step 12

No

Go to the next step.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

90

S/N

Operating Step

Operation

Detection
Result

Next Step

4

Using

diagnostic

instrument to read
wheel speed data
stream

(a) Connect the diagnostic instrument to read data stream.

(b) One repair main conduct test run uniformly in a straight
line on good road surface and the other one observe the
data stream.

Normal state: The displayed speed of each wheel is
basically the same.

Tip: Allowable error for speedometer is ±10%.

Normal

Go to Step 8

Abnormal

Check wheel speed sensors.

5

Checking

wheel

speed sensors

(a)

Remove the connector of wheel speed sensor to

measure the internal resistance of wheel speed sensor.

Normal value: 3MΩ～5MΩ

(b) Measure the wheel speed sensor’s resistance to ground.

Normal value: ∞

Normal

Go to the next step.

Abnormal

Replace relevant wheel speed
sensor.

6

Ensuring

the

wheel

speed

sensor

correctly

connected

Use multimeter to measure the cable resistance.

Normal value: 0Ω

Normal

Go to the next step.

Abnormal

Repair or replace it.

7

Using oscilloscope
to

check

wheel

speed sensor and
its waveform

(a) Remove the connector from wheel speed sensor.

(b) One terminal of sensor is connected with 12V battery

and the other terminal connected with red pen of
oscilloscope.

Attention: Ground cable of oscilloscope must be connected
with ground cable of battery.

Please drive carefully and ensure connecting wire not
interfered with motion parts of vehicle.

Normal

Repair or replace the ABS
assembly.

Abnormal

Go to the next step.

8

Checking

wheel

speed

sensor

harness

Wheel speed sensor adopts twisted pair to provide effective
shield so as to protect sensitive electronic elements from
being affected by electrical interference.

To avoid performance degradation due to electrical
interference, the following requirements should be satisfied
during maintaining the twisted pair:

(a) Wind the wire by 9 loops every 310mm along the

length direction of the wire.

(b) The external diameter of twisted pair shall be no more

than 6.0mm.

Normal

Go to the next step.

Abnormal

Repair

9

Checking

the

installation

of

wheel

speed

sensor

Normal

Go to the next step.

Abnormal

Repair

10

Checking

wheel

speed sensor probe

Normal

Go to the next step.

Abnormal

Clean or replace it.

11

Checking

wheel

speed sensor rotor

Normal

Check or replace the ABS
assembly.

Abnormal

Clean or replace the gear
ring.

12

Conduct final inspection to confirm the fault is removed. Clear DTC.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

91

Diagnosis

Diagnosis

Diagnosis

Diagnosis and

and

and

and Testing

Testing

Testing

Testing

2.

Hydraulic governor solenoid valve fault: C0060, C0065, C0070, C0075, C0080, C0085, C0090, C0095

Circuit

Circuit

Circuit

Circuit description

description

description

description::::

With the ignition switch turned on and ABS solenoid valve relay powered on, battery voltage can be provided to one
terminal of solenoid valve of hydraulic governor.

With ignition switch turned off or ABS system disabled, the solenoid valve relay should be kept power-on.

Function:

ABS ECU is applied to control the operation of solenoid valves through controlling their grounding so as to regulate
brake pressure of each brake circuit.

Inlet valves: PWM type.

Outlet valves: Switch type.

DTC

Detection Condition

Set Condition

Possible Faulty Areas

C0060

C0065

C0070

C0075

C0080

C0085

C0090

C0095

To be conducted at the
same time of ABS
ECU initialization and
self-checking:

Vehicle

under

stationary

state

or

speed ≥15Km/h

1. With the ignition switch turned on, ABS ECU

detects relevant solenoid valve circuit short to
power

or

ground

permanently

or

intermittently.

2. Activate relevant solenoid valve but without

feedback.

3. Coil or connector fault of solenoid valve is

detected during travelling:

–

Without brake pedal depressed: Vehicle under
stationary state

–

With brake pedal depressed: Vehicle speed
≈15Km/h

4. Under all conditions, fault occurs in oil

circuit of ABS hydraulic governor with ECU.

1. Fault of solenoid valve

inside ABS hydraulic
governor

with

ECU:

brake oil circuit fault,
electrical fault.

2. Hydraulic/mechanical

fault.

Occurrence of fault shall give rise to the following operation:

Braking Strategy

Failure Protection

Solenoid valve failed to operate or operating wrongly

If the solenoid valve failed to operate, relevant wheel
may be locked. If it operates wrongly, no oil pressure
shall be established for relevant wheel.

Brake system shall enter the conventional braking mode.

ABS and EBD warning lamps shall be lit.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

92

Troubleshooting

Troubleshooting

Troubleshooting

Troubleshooting procedures

procedures

procedures

procedures

S/N

Operating Step

Operation

Detection

Result

Next Step

1

Checking

ABS

hydraulic

governor

with

ECU

under

stationary

state

of

vehicle

(a) Turn off the ignition switch;
(b) Turn on the ignition switch without brake pedal depressed;
(c) Check if ABS and EBD warning lamps are lit and when

necessary use diagnostic instrument to read DTC. If it is
normal, ABS/EBD warning lamp shall go out without
current DTC.

Normal

Go to the next step.

Abnormal

Go to Step 3

2

Using

diagnostic

instrument to perform
component testing for
solenoid

valve

of

ABS

hydraulic

governor with ECU

Remarks:
① Before testing solenoid valve, please test he reflux pump to

see if it operates normally.

② Two repair men are required to finish this test.
(a)

Turn off the ignition switch;

(b)

Connect the diagnostic instrument to DLC;

(c)

One repair man should sit in the vehicle and the vehicle

should be lifted by lifter with wheels suspended;

(d)

Turn on the ignition switch with engine off;

(e)

Apply the “Component Test” function of diagnostic

instrument to activate the solenoid valve as per prompt of
diagnostic instrument;

(f) Firstly, test the oil inlet valve and oil outlet valve of left

front wheel, during which, the repair man in the vehicle
should depress the brake pedal with force and hold it.

① Conventional braking phase

Normal state: The repair man outside cannot rotate the left

front wheel by hand.

② Boosting phase: Use diagnostic instrument to access the

“boosting phase”.

Normal state: The repair man outside cannot rotate the left

front wheel by hand.

③ Pressure maintenance phase: Use diagnostic instrument to

access the “pressure maintenance phase”.

Normal state: The repair man outside cannot rotate the left

front wheel by hand.

④ Pressure reducing phase: Use diagnostic instrument to

access the “pressure reducing phase”.

Normal state: The repair man outside can rotate the left

front wheel by hand.

(g) Perform testing for right front, left rear and right rear

wheels in sequence. The test results should be the same as
those of left front wheel.

Normal

Go to the next step.

Abnormal

Replace

ABS

control

unit assembly.

3

Checking pin voltage
of

ABS

hydraulic

governor with ECU

(a) Turn off the ignition switch;
(b) Remove connectors from ABS hydraulic governor with

ECU;

(c) Use multimeter to measure the voltage at the power

terminal and grounding terminal of solenoid valve.

Remarks:
If no jumper box is applied, the normal detection cannot be
ensured.
Normal value: U = 9.3 ～ 16.9V

Normal

Replace

ABS

control

unit assembly.

Abnormal

Go to the next step.

4

Checking connecting
wires, connectors and
40A fuse

(a) Check if 25A fuse is normal;
(b) Check the charging system, such as generator/battery and

its connecting wire;

(c) Ensure the grounding terminal is well grounded.

Normal

Go to the next step.

Abnormal

Replace

or

repair

connecting
wire/connector or fuse.

5

Final inspection

(a) Clear DTC;
(b) ABS and EBD warning lamps shall go out shortly after the ignition switch is turned on;
(c) With the ignition switch turned on, C0060, C0065, C0070, C0075, C0080, C0085, C0090 or C0095

DTC shall not appear any more after self-checking is finished by system.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

93

Diagnosis

Diagnosis

Diagnosis

Diagnosis and

and

and

and Testing

Testing

Testing

Testing

3.

Reflux pump motor fault: C0110

Circuit description:

ABS hydraulic unit with ECU integrates reflux pump with motor. Reflux pump relay shall stop operation and the
reflux pump shall be under stationary state if no regulation is performed by ABS. When decompression is regulated by
ABS, ABS ECU shall control the operation of reflux pump motor through controlling the grounding of reflux pump
relay.

Function:
�

ABS Pressure reducing phase: Reflux pump shall operate to pump the brake fluid in the wheel cylinder of locked
wheel back into the master cylinder line so as to reduce the pressure of wheel cylinder.

�

EBD Pressure reducing phase: Pressure accumulator shall store the brake fluid flowed back from rear wheels.

DTC

Detection Condition

Set Condition

Possible Faulty Areas

C0110

To be conducted at the
same time of ABS ECU
initialization

and

self-checking:

Vehicle

under

stationary state or speed
≥15Km/h

1. After the reflux pump motor relay

operates for 60ms, still no voltage
signal can be detected by reflux
pump monitoring.

2. Under no operation of reflux pump

motor relay, voltage detected by
reflux pump monitoring exceeds
2.5s.

3. If the reflux pump motor relay stop

operation,

no

voltage

drop

is

detected

by

reflux

pump

monitoring.

1.

“Reflux pump motor circuit”

inside ABS.

2. Open circuit of reflux pump

motor relay.

3. Fault of reflux pump motor relay.

4. Fault

of

reflux

pump

motor

wiring.

5. Imperfect ground.

6. Inadequate power supply.

7. Fault of reflux pump motor.

Occurrence of fault shall give rise to the following operation:

Braking Strategy

Failure Protection

�

Fault of reflux pump relay: Reflux pump failed to
operate

�

Wheel brake force control is disabled due to no
back-flow pressure can be generated. System shall
perform conventional braking.

�

Brake system shall enter the conventional braking
mode.

�

ABS and EBD warning lamps shall be lit.

Remarks:

If the ignition switch is turned on after fault removal, the ABS and EBD warning lamps shall go out automatically
when the vehicle speed exceeds 12Km/h.

Troubleshooting procedures

S/N

Operating Step

Operation

Detection
Result

Next Step

1

Parking the vehicle to
check ABS hydraulic
governor with ECU

(a) Turn off the ignition switch;

(b) Is any noise heard from ABS hydraulic governor?

Normal state: ABS reflux pump shall stop operation.

Normal

Go to the next step.

Abnormal

Go to Step 4

2

Inspection

of

self-checking
initializer

of

ABS

hydraulic

governor

with ECU

(a) Start the engine;

(b) Run at speed of 10～15Km/h without brake pedal

depressed;

(c) Check if ABS warning lamp is lit and when necessary

use diagnostic instrument to read DTC.

Normal state: ABS warning lamp shall go out without
DTC memory in ABS ECU.

Normal

Go to the next step.

Abnormal

Repair

based

on

DTC.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

94

S/N

Operating Step

Operation

Detection
Result

Next Step

3

Using

diagnostic

instrument to perform
component testing for
ABS

hydraulic

governor with ECU

(a) Turn off the ignition switch;

(b) Connect the diagnostic instrument to OBD port;

(c) Turn on the ignition switch with engine off;

(d) Apply the “Component Test” function of diagnostic

instrument to activate the reflux pump.

Normal state: Operation sound of reflux pump can be
heard.

Normal

Go to the next step.

Abnormal

Replace ABS control
unit assembly.

4

Checking pin voltage
of

ABS

hydraulic

governor with ECU

When using multimeter:

(a) Turn off the ignition switch;

(b) Remove connectors from ABS hydraulic governor with
ECU;

(c) Use multimeter to measure the voltage at the power
terminal and grounding terminal of reflux pump.

Remarks:

If no jumper box is applied, the normal detection cannot be
ensured.

Normal value: U=9.3～16.9V

Normal

Replace ABS control
unit assembly.

Abnormal

Go to the next step.

5

Checking

connecting

wires, connectors and
40A fuse

(a) Check if 40A fuse is normal;

(b) Check the charging system, such as generator/battery

and its connecting wire;

(c) Ensure the grounding terminal is well grounded.

Normal

Go to the next step.

Abnormal

Replace

or

repair

connecting
wire/connector

or

fuse.

6

Final inspection.

(a) Clear DTC;

(b) ABS and EBD warning lamps shall go out shortly after the ignition switch is turned on;

(c) C0110 DTC shall no longer appear with the ignition switch turned on;

(d) When travelling at speed of 10～15Km/h, C0110 DTC shall no longer appear without brake pedal

depressed.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

95

Diagnosis

Diagnosis

Diagnosis

Diagnosis and

and

and

and Testing

Testing

Testing

Testing

4.

Solenoid valve relay circuit fault: C0121

Circuit description:

With the ignition switch turned on and ABS solenoid valve relay powered on, battery voltage can be provided to one
terminal of solenoid valve of hydraulic governor.

With ignition switch turned off or ABS system disabled, the solenoid valve relay should be kept power-on.

Function:

ABS ECU is applied to control the operation of solenoid valves through controlling their grounding so as to regulate
brake pressure of each brake circuit.

DTC

Detection Condition

Set Condition

Possible Faulty Areas

C0121

1. With

the

ignition

switch turned on and
in the course of fault
testing

2. In the course of ABS

operation

Short circuit of solenoid valve, or
voltage circuit short to Uz or ground, or
fuse blowout is detected.

The

time

of

voltage

supplied

for

solenoid valve detected to be ＜0.8*Uz
(≈8.0V) exceeds 0.8s.

1.

“Solenoid valve relay circuit”

inside ABS.

2. Inadequate power supply.

3. Short circuit.

4. Open circuit.

Occurrence of fault shall give rise to the following operation:

Braking Strategy

Failure Protection

�

Fault of solenoid valve relay: Solenoid valve failed to
operate

�

Brake system shall enter the conventional braking
mode.

�

ABS and EBD warning lamps shall be lit.

�

If the solenoid valve relay stop operation due to fault
of audion in ECU,

�

The system shall be converted to EBD emergency
control mode.

�

ABS warning lamp shall be lit.

Troubleshooting

Troubleshooting

Troubleshooting

Troubleshooting procedures:

procedures:

procedures:

procedures:

S/N

Operating Step

Operation

Detection
Result

Next Step

1

Checking

ABS

hydraulic

governor

with

ECU

under

stationary

state

of

vehicle

(a) Turn off the ignition switch;
(b) Turn on the ignition switch without brake pedal

depressed;

(c) Check if ABS and EBD warning lamps are lit and when

necessary use diagnostic instrument to read DTC.
Normal state: ABS/EBD warning lamp shall go out
without current DTC.

Normal

Go to the next step.

Abnormal

Go to Step 3

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

96

S/N

Operating Step

Operation

Detection
Result

Next Step

2

Using

diagnostic

instrument to perform
component testing for
solenoid valve of ABS
hydraulic

governor

with ECU

Remarks:
① Before testing solenoid valve, please test he reflux pump

to see if it operates normally.

② Two repair men are required to finish this test.
(a) Turn off the ignition switch;
(b) Connect the diagnostic instrument to DLC.
(c) One repair man should sit in the vehicle and the vehicle

should be lifted by lifter with wheels suspended.

(d) Turn on the ignition switch with engine off.
(e) Apply the “Component Test” function of diagnostic

instrument to activate the solenoid valve as per prompt of
diagnostic instrument.

(f) Firstly, test the oil inlet valve and oil outlet valve of left

front wheel, during which, the repair man in the vehicle
should depress the brake pedal with force and hold it.

① Conventional braking phase:

Normal state: The repair man outside cannot rotate the
left front wheel by hand.

② Boosting phase: Use diagnostic instrument to access the

“boosting phase”.
Normal state: The repair man outside cannot rotate the
left front wheel by hand.

③ Pressure maintenance phase: Use diagnostic instrument to

access the “pressure maintenance phase”.
Normal state: The repair man outside cannot rotate the
left front wheel by hand.

④ Pressure reducing phase: Use diagnostic instrument to

access the “pressure reducing phase”.
Normal state: The repair man outside can rotate the left
front wheel by hand.

(g) Perform testing for right front, left rear and right rear

wheels in sequence.
The test results should be the same as those of left front
wheel.

Normal

Go to the next step.

Abnormal

Replace

ABS

control

unit assembly.

3

Checking pin voltage
of

ABS

hydraulic

governor with ECU

When using multimeter:
(a) Turn off the ignition switch
(b) Remove connectors from ABS hydraulic governor with

ECU.

(c) Use multimeter to measure the voltage at the power

terminal and grounding terminal of solenoid valve.

Remarks:

If no jumper box is applied, the normal detection cannot
be ensured.
Normal value: U=9.3～16.9V

Normal

Replace ABS hydraulic
governor with ECU.

Abnormal

Go to the next step.

4

Checking

connecting

wires, connectors and
40A fuse

(a) Check if 25A fuse is normal.
(b) Check the charging system, such as generator/battery and

its connecting wire.

(c) Ensure the grounding terminal is well grounded.

Normal

Go to the next step.

Abnormal

Replace

or

repair

connecting
wire/connector or fuse.

5

Final inspection.

(a) Clear DTC.
(b) ABS and EBD warning lamps shall go out shortly after the ignition switch is turned on
(c) With the ignition switch turned on, C0121 DTC shall no longer appear after self-checking is

finished by system.

(d) Perform Step 2 in this procedure and the testing result is normal.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

97

Diagnosis

Diagnosis

Diagnosis

Diagnosis and

and

and

and Testing

Testing

Testing

Testing

5.

ABS brake lamp switch circuit fault: C0161

Circuit description:

Brake lamp switch is a kind of normally open switch.

This switch shall be on with the brake pedal depressed, providing +12V signal voltage to brake lamp signal circuit
(+BLS).

ABS ECU shall monitor the brake lamp switch signal voltage to facilitate the determination of brake engagement time
and the detection of brake lamp switch circuit.

DTC

Detection Condition

Set Condition

Possible Faulty Areas

C0161

1. With ignition switch turned on

2. Battery voltage＞8V

3. Vehicle speed＞16Km/h

1. The brake pedal is detected to

be

depressed

under

the

conditions below:

Vehicle speed＞40Km/h

Acceleration＞8Km/h2

2. The brake pedal is detected to

be

released

under

the

conditions below:

Vehicle speed＞24Km/h

Acceleration＞11.5Km/h2

1. Brake lamp switch

2. Brake

lamp

switch

circuit

3. Brake

lamp

switch

connector

4. ABS ground

5. ABS

hydraulic

governor with ECU

Troubleshooting

Troubleshooting

Troubleshooting

Troubleshooting procedures:

procedures:

procedures:

procedures:

S/N

Operating Step

Operation

Detection

Result

Next Step

1

Checking brake lamp switch
block

(a) Depress and release brake pedal to check brake lamp.

With brake pedal depressed: Brake lamp shall be lit.

With brake pedal released: Brake lamp shall go out.

Remarks: Please ensure the brake lamp and its circuit
is normal when using this method to diagnose the
brake lamp switch.

(b) Check brake lamp switch based on data stream of

diagnostic instrument.

With brake pedal depressed: “Engagement” shall be
displayed on diagnostic instrument.

With brake pedal released: “Disengagement” shall be
displayed on diagnostic instrument.

Normal

Go to the next step.

Abnormal

Go to Step 4

2

Checking pin voltage of
ABS

hydraulic

governor

with ECU (Voltage of Pin
30 corresponding to

Pin

38)

(a) Turn off the ignition switch.

(b) Remove connector from ABS hydraulic governor.

(c) Turn on the ignition switch.

(d) Use multimeter to measure the voltage between brake

lamp switch terminal and grounding terminal.

With brake pedal depressed: Voltage＜2V→Brake
lamp shall be lit.

With brake pedal released: Voltage ＞ 4.5V→Brake
lamp shall go out.

Normal

Go to the next step.

Abnormal

Replace ABS with
hydraulic governor.

3

Checking connecting wire
and

connector

(between

brake lamp switch and ABS
hydraulic

governor

with

ECU)

Checking connecting wire and connector between brake lamp switch and ABS hydraulic
governor for short circuit or open circuit.

4

Checking connecting wire
and connector (brake lamp
switch circuit)

Check the brake lamp switch circuit for short circuit or open circuit.

5

Final inspection.

Confirm that the fault shall no longer appear.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

98

Diagnosis

Diagnosis

Diagnosis

Diagnosis and

and

and

and Testing

Testing

Testing

Testing

6.

ABS ECU fault: C0550

Circuit description:

ABS ECU, installed in ABS hydraulic governor with ECU, is the control center of ABS system. Programmable and
calibration data required by ABS operation are stored in ROM of ABS ECU. ABS ECU shall perform self-checking
continuously to monitor any fault in ABS system.

DTC

Detection Condition

Set Condition

Possible Faulty Areas

C0550

With ignition switch turned on

With engine running and under
all conditions

Under all conditions

Fault is detected immediately.

Fault is detected immediately.

It is detected that wheel speed sensor
power circuit is short to Uz.

1. ABS

hydraulic

governor with ECU.

2. Circuit.

Occurrence of fault shall give rise to the following operation:

Braking Strategy

Failure Protection

Stop operation

�

Brake system shall enter the conventional braking mode.

�

ABS and EBD warning lamps shall be lit.

Troubleshooting

Troubleshooting

Troubleshooting

Troubleshooting procedures:

procedures:

procedures:

procedures:

S/N

Operating Step

Operation

Detection Result

Next Step

1

ABS

hydraulic

governor

with

ECU

under stationary state
of vehicle

(a) Turn off the ignition switch;

(b) Turn on the ignition switch without brake pedal

depressed;

(c) Check if ABS and EBD warning lamps are lit and when

necessary use diagnostic instrument to read DTC.

Normal state: ABS/EBD warning lamp shall go out
without current DTC.

Normal

Check

based

on

other DTC.

Abnormal

Go to the next step.

2

Detection of system

circuit

(a) Check all ground circuit of ABS hydraulic governor

with ECU for excessive resistance or open circuit.

(b) Check ABS fuse and when necessary replace it.

(c) Check ABS battery power supply voltage circuit for

excessive resistance, open circuit or short to ground.

(d) Check if the wheel speed sensor power line is short to

main power line.

(e) Check for any electromagnetic interference.

Is the fault eliminated?

Yes

Go to Step 4

No

Go to the next step.

3

Replacement of ABS
hydraulic

governor

with ECU.

Replace the ABS hydraulic governor with ECU as a whole.

4

Conduct

final

inspection to confirm
the fault is removed.

(a)

Clear DTC.

(b)

With ignition switch turned on, ABS has no DTC memory.

ABS

ABS

ABS

ABS Anti-lock

Anti-lock

Anti-lock

Anti-lock Brake

Brake

Brake

Brake System

System

System

System

99

Diagnosis

Diagnosis

Diagnosis

Diagnosis and

and

and

and Testing

Testing

Testing

Testing

7.

Voltage out of range: C0800

Circuit description:

ABS ECU monitors the battery power supply voltage supplied to ABS ECU through Uz. If the voltage is out of the
specified range, the following faults shall occur:

Too low voltage supplied to ABS ECU may lead to abnormal operation of ABS system.

Too high voltage supplied to ABS ECU may lead to damage of ABS components.

Normal operating voltage of system: 9.3V～16.9V under operation of reflux pump motor

DTC

Detection
Condition

Set Condition

Possible Faulty Areas

C0800

With

ignition

switch

turned

on

1. If the voltage is below 9.6V with no operation

of ABS, or below 9.3V with operation of ABS,
this DTC shall be recorded and ABS shall be
turned off by software.

2. If voltage below 7.6V or above 16.9V is

continuously monitored, this DTC shall be
recorded and ABS and EBD shall be turned off
by hardware.

1. Overdischarge or damage of

battery.

2. Fault of voltage regulator

(charging system).

3. Fault of fuse or connector,

imperfect body grounding, or
contact resistance.

Occurrence of fault shall give rise to the following operation:

Braking Strategy

Failure Protection

Normal operation of reflux pump motor and solenoid
valve cannot be ensured.

Brake system shall enter the conventional braking
mode.

ABS and EBD warning lamps shall be lit.

If the voltage is far below 9.6V

The system shall be converted to EBD emergency
control mode.

ABS warning lamp shall be lit.

If the voltage is far above 7.6V

Brake system shall enter the conventional braking
mode.

ABS and EBD warning lamps shall be lit.

Voltage Uz is above 9.8V after a period of too low
voltage.

System shall retreat from the EBD emergency
operation mode.

Normal operation of ABS shall recover.