JAC S2 (Chassis). Instruction — part 11

Parking Brake System

Parking brake system

150

(I) In-car check

△Notice Check and adjust parking brake system only
when the brake works normally
△Notice While checking parking brake system, the car
must be parked on even ground, with wheels being fixed
by wedges

Check spare parts

1. Check whether all spare parts are fixed normally
2. Check whether the brake handle is crooked, broken or has cracks, and change the handle if necessary
3.Check whether the fibre-drawings are worn or broken, and change them if necessary
4. Check whether the indicator lamp switch works normally, and repair&change the lamp if it doesn’t
work
5. Dismantle the switch connector of parking brake, and check the continuity between positive terminal
and car body. The circuit should be on when the handle is pulled up, and off when the handle is pulled
down

Check the working distance of parking brake

1. Pull up the parking brake, and confirm that when the handle is pulled up, the number of teeth that the
handle passed stays in standard

Standard teeth number: 7~9
△Notice there will be a tick every time when the handle
passes a tooth, by counting the tick, you can judge
whether the brake handle works in standard when pulled
up

Adjust the working distance of parking brake

1. Open the engine hood
2. Dismantle the vice dashboard, please refer to “vice dashboard”
3. Adjust the working distance of parking brake handle

1). Adjust the adjusting nut on the parking brake system,
and ensure the distance (L) between the adjusting nut and
the final part of fibre-drawing stays in standard

Standard: L=20~25mm

Standard teeth number: 7~9
△Notice Decrease L if the number of passed teeth is less
than 7, and increase L if the number of passed teeth is
more than 9

4. Pull down the parking brake
5. Check whether the rear wheels are delayed when parking

IV Parking brake switch

(I) Disassembly

1. Open the engine hood
2. Disconnect the negative cable of battery
3. Dismantle the vice dashboard, please refer to “vice
dashboard”

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4. Remove the parking brake switch

1). Pull down the parking brake handle

2). Disconnector the harness connector of parking brake
lamp

3). Loosen the fixed bolt of parking brake switch and take
off the switch

(II) Installation

1. Install the parking brake switch

1). Install the fixed bolt of parking brake switch

Tightening torque 6~8N.m

2). Connect the harness connector of parking brake
switch

2. Install the vice dashboard
3. Connect the negative cable of battery
4. Close the engine hood

V Parking brake system assembly

(I) Disassembly

1. Open the engine hood
2. Disconnect the negative cable of battery
3. Dismantle the vice dashboard, please refer to “vice dashboard”
4. Disassemble the parking brake switch, please refer to “parking brake switch”
5. Disassemble the parking brake system assembly

1). Loosen the nut on the adjusting sprial

2). Loosen the two fixed bolts that connect parking brake
system assembly and car body

3). Disconnect fibre-drawing from balance bar

4). Take off the parking brake system

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(II) Installation

1. Install the parking brake system assembly

1). Tighten the two fixing bolts that connect parking brake
system assembly and car body

Tightening torque 20~25N.m

2). Adjust the nut into a proper position on the final part
of threaded rod, and install the fibre-drawing on the
balance bar

2. Check and adjust the parking brake system assembly,
please refer to “Check and adjustment on the assembly of
parking brake system”
3. Install the parking brake switch
4. Install the vice dashboard
5. Connect the negative cable of battery
6. Close the engine hood

VI Parking brake fibre-drawing assembly

(I) Disassembly

1. Open the engine hood
2. Disconnect the negative cable of battery
3. Dismantle the vice dashboard, please refer to “Vice dashboard”
4. Disassemble the parking brake system assembly, please refer to “Parking brake system assembly”
5. Remove the rear wheels, please refer to “Wheel”
6. Disassemble the rear brake caliper, please refer to
“Front brake caliper assembly”
7. Remove thermal baffle I and II, please refer to
“Thermal baffle”
8. Disassemble the parking brake fibre-drawing assembly

1). Adjust the nut on the final part of thredded rod

2). Disconnect the left-rear and right-rear parking brake
fibre-drawing from balance plate

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3). Remove the bolts and nuts on the fixing support

4). Take out the fibre-drawing from the mounting sleeves
that locate in the bottom of the car

5). Disconnect the parking brake fibre-drawing and
parking brake disc

6). Take off the parking brake fibre-drawing assembly

(II) Installation

1. Install the parking brake fibre-drawing

1). Connect the parking brake fibre-drawing and parking
brake disc

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2). Tighten the bolts and nuts on the fixing support of
parking brake fibre-drawing

Tightening torque 7~11N.m
△Notice the route of fibre-drawings should be smooth

3). Install the fibre-drawings into the mounting sleeves
that locate on the bottom of the car.

4). Install the left-rear and right-rear parking brake
fibre-drawings on the balance plate

2. Check and adjust the parking brake system assembly, please refer to “Check and adjustment on the
assembly of parking brake system”
3. Install the vice dashboard
4. Install the rear brake caliper assembly
5. Install the rear wheels
6. Install the thermal baffle I and II
7. Connect the negative cable of battery
8. Close the engine hood

Brake Control System

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Brake Control System

I General introduction

(I) Brief introduction on structure

Structural diagram of brake system (front & rear braking disc model)

1. Front wheel’s ABS speed sensor assembly 3. ESP controller assembly
2. Rear wheel’s ABS speed sensor assembly 4. ESP controller’s fixing support

(II) System function

1. ABS

ABS (anti-skid brake system) can control the hydraulic brake force on wheels during emergency braking
or braking when the road situation is dangerous, and prevent wheels from skidding. ABS has the
following advantages:

(1) Steering will be reliable when facing obstacles during
emergency braking

(2) The vehicle can stop steadily on curve roads during
emergency braking

2. ESP

ESP (electronic stability program) is an active safety system. It is a dependent system based on other

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driving control system. ESP includes all functions of ABS, and increases TCS (traction control system).
Meanwhile, additional functions can be applied on it by adding sensors and input signals.

Basic functions:

ABS (anti-skid brake system)

EBD (electric brake force distribution)

AYC (active yawing control)

TCS (traction control system)

Braking assistance:

HBA (hydraulic braking assistance)

Static control system:

HAS (hill-start assist system)

ESP can judge the working conditions of vehicles by analyzing signals provided by steering sensor, wheel
sensor, yawing sensor, transverse acceleration sensor and etc. After analysis, it sends rectifying signals to
ABS and ASR, so as to help the vehicle to maintain mobile balance and achieve utmost stability under
various situations. Its performance will be more apparent when the steering process is excessive or
insufficient.

3. EBD

Each wheel’s adhesion coefficient provided by ground will be different as the situation of road to which
the wheel sticks will be different. What’s more, the vehicle’s barycenter will change during emergency
brake, which may lead to vehicle’s skid, bias or roll-over. During the moment of emergency brake, EBD
can instantly figure out the friction’s numerical difference due to wheels’ different adhesion coefficients.
Then it adjusts the electromagnetic valves in hydraulic units, so they can adjust themselves instantly
during dynamic situation. It can achieve the match of break force and friction, and ensure the vehicle’s
stability and safety. During emergency brake, EBD will balance each wheel’s valid traction before ABS,
and prevents the vehicle from whipping or side-swing. Generally speaking, EBD is an additional function
of ABS. it can distribute brake force automatically according to the changes of road situation and carrying
capacity, and improve ABS’s performance.

EBD can control each wheel’s break force precisely and ensure the vehicle’s stability. On normal
breaking situation, it can effectively equal each wheel’s speed. By controlling the input & output oil
valves of hydraulic adjustment module in ABS, EBD can control each wheel’s breaking pressure in order
to provide effective breaking and stability for vehicles.

4. TCS

TCS can monitor the slippage rate of driving wheels. If the rate is too big, TCS will send signals to engine,
decreasing the amount of fuel injected by nozzle, or the opening of throttle valve, thus decreasing the
torque output, and optimizing the drive wheel’s slippage rate, which promises drive wheels with bigger
adhesion force. If the difference between the drive wheels’ adhesion coefficients is too large, TCS will
actively impose break force to the drive wheel which has low coefficient, prevent the wheel from skidding,
and ensure the drive wheel which has larger coefficient to gain bigger drive force.

5. Failure protection

If electric failure happens in ABS or ESP, the warning light of ABS or ESP will automatically turn on. If
electric failure happens in EBD, the brake warning light and ABS warning light will turn on. Meanwhile,
ABS will change into one of the following failure protection:

1) For ABS’s failure, only EBD will be activated, and the

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vehicle’s condition will be the same as the one without
ABS.

2) For EBD’s failure, neither EBD nor ABS will be
available, and the vehicle’s condition will be the same as
the one without ABS or EBD.

(III) Working principle

Diagram of ABS’s hydraulic working principle

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Diagram of ABS

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Diagram of ESP’s hydraulic working principle

Anti-skid brake mode

During vehicle’s brake, should the wheels skid, ABS will be activated into anti-skid brake mode. During
this period, all wheels’ hydraulic pressure will be under control in case of slippage. Each wheel has its
own hydraulic pipeline and valve. ABS can change, or maintain each wheel’s hydraulic pressure during
vehicle’s brake. However, ABS cannot increase the hydraulic pressure to the amount which the master
cylinder transfers during brake. Thus, during anti-skid brake, the brake pedal will vibrate quickly. The
vibration is triggered by the quick changes of each valve’s position. This kind of vibration will appear
during anti-skid brake mode, and stop during normal brake or when the vehicle completely stops. As the
electromagnetic valve circulates quickly, there will be some noise. If the anti-skid mode is activated when
the vehicle is on dry roads, harsh noise will appear intermittently when the wheels are close to slippage.
All these noise and vibration are normal circumstances during anti-skid brake. When you stamp the pedal
during narmal brake, the operation should be the same when you drive the one without ABS. keeping the
power balance during stamping pedal can promise shortest braking distance while maintaining the
vehicle’s stability.

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During anti-skid brake period, the brake system’s pressure adjustment can be divided into three phases.
1. Pressure maintenance

When the slippage was detected by ABS control module, it will close oil inlet valve, and close the oil
outlet valve in hydraulic assembly to isolate the system. This will maintain the pressure stability of
arrester and keep the hydraulic pressure still.

2. Pressure reduction

Should slippage still was detected by ABS control mode under pressure maintenance mode, ABS will
reduce the pressure of the wheel which was affected. It will close oil inlet valve, and open oil outlet valve.
Redundant fluid or pressure will be stored temporally in the power accumulator of hydraulic assembly
until when the pump motor sends the brake fluid back to the reservoir of master cylinder

3. Pressure increase

If ABS control module detects that the wheel slippage has reduced under pressure maintenance or
reduction mode, the module will use the pressure of cylinder to increase the affected wheel’s pressure.
The oil inlet valve will open, and the oil outlet valve will be closed. Part or all pressure from brake
system’s master cylinder will be added to wheels.

The working process of ABS

When the vehicle is moving, rach wheel speed sensor will produce an voltage signal which is proportional
to the wheel’s rotational speed. ABS controller will receive the speed data and determine whether one or
more wheels’ speed reduction is too fast, and activate control module if needs. The module will control
and optimize each wheel’s brake pressure.

II ABS&ESP control module

(I) Components

The front-disc-rear-drum model applies BOSCH ABS 9, with ABS control module and hydraulic
assembly being integrated together; the front-disc-rear-disc model applies BOSCH ESP 9, with ESP
control module and hydraulic assembly being integrated together.

(II) Illustration of the stitch on ABS, ESP control module

Illustration of stitch in ABS control module

Stitch
No.

Illustration

Stitch
No.

Illustration

1

Motor’s battery terminal (positive)

2

Speed sensor output (right-front wheel)

3

Active EBD warning light

4

Speed sensor’s signal terminal (right-
front)

5

N.C.

6

K line

7

N.C.

8

Speed sensor’s signal terminal (left-
front)

9

N.C.

10

N.C.

11

N.C.

12

N.C.

13

Motor’searth terminal

14

CAN-low

15

N.C.

16

Speed sensor’s power terminal (right-
front)

17

Speed sensor’s power terminal (right-
rear)

18

Speed sensor’s signal terminal (left-
rear)

19

Speed sensor’s power terminal (left-
front)

20

N.C.

21

N.C.

22

N.C.

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23

N.C.

24

N.C.

25

Valve relay’s power terminal

26

CAN-high

27

Active ABS warning light

28

ECU’s power terminal (ignition cable)

29

Speed sensor’s signal terminal (right-
rear)

30

Brake light switch input

31

Speed sensor’s signal terminal (left-
rear)

32

N.C.

33

Speed signal output

34

N.C.

35

N.C.

36

N.C.

37

N.C.

38

ECU’s earth wire

Diagram of the stitch’s position in ABS control module

Illustration of stitch in ESP control module

Stitch
No.

Illustration

Stitch
No.

Illustration

1

Motor’s battery terminal (positive)

2

Speed sensor output (right-front wheel)

3

N.C.

4

Speed sensor’s signal terminal (right-
front)

5

N.C.

6

N.C.

7

N.C.

8

Speed sensor’s signal terminal (left-
front)

9

N.C.

10

N.C.

11

N.C.

12

ESP switch

13

Motor’s earth terminal

14

CAN- low

15

N.C.

16

Speed sensor’s power terminal (right-
front)

17

Speed sensor’s power terminal (right-
rear)

18

Speed sensor’s signal terminal (left-
rear)

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19

Speed sensor’s power terminal (left-
front)

20

N.C.

21

N.C.

22

N.C.

23

N.C.

24

N.C.

25

Valve relay’s power terminal

26

CAN- high

27

N.C.

28

ECU’s power terminal (ignition cable)

29

Speed sensor’s signal terminal (right-
rear)

30

Brake light switch input

31

Speed sensor’s power terminal (left-
rear)

32

N.C.

33

N.C.

34

N.C.

35

N.C.

36

N.C.

37

N.C.

38

ECU’s earth wire

Diagram of the stitch’s position in ESP control module

(III) Check on ABS&ESP control module

△Notice please go on basic check on brake system first

Basic check on brake system

1. Check the liquid level of brake fluid, and add brake fluid if necessary
2. Check whether any leakage exists in brake pipeline or ABS hydraulic assembly. Should the leakage
exists, please make the following checks:

a: If the connector part of ABS hydraulic assembly is
loosen, please tighten the tubing nut to the designated
torque (16~18N.m), check the leakage situation again, and
make sure no brake fluid leaks.

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b: If the connector part’s tubing nut or the actuator’s
whorl part is broken, please replace the broken parts and
check the leage again. Make sure no break fluid leaks.

c: If no leakage exists except in actuator’s connector part,
use clean rags to wipe the stain and check again. Should
the leakage still exists, please replace the broken part.

d: If the leakage exists on hydraulic assembly, use clean
rags to wipe the stain and check again. Should the leakage
still exists, please replace the hydraulic assembly.
△Notice do not disassemblr ABS or ESP hydraulic
assembly unless with special needs.

3. Check whether the filler block or the shoe plate is broken.
4. Check whether the circuit terminal or the battery is loosen.

△Notice check whether the battery’s positive/negative
terminal is loosen, and confirm whether the battery’s
voltage is normal

Check the warning light of ABS and brake system

1). Check whether when the ignition switch turns to “ON”,
the ABS warning light will light for 3 seconds, and the
brake warning light keep lighting. If they don’t light,
please refer to “common failures and analysis process of
ABS”

2). Check whether after 3 seconds when the ignition
switch turns to “ON”, the ABS warning light will go out,
and the brake warning light will go out after the engine
starts. If not, please refer to “common failures and
analysis process of ABS”

3). If the ABS warning light doesn’t go out in 10 seconds
after the engine starts, please refer to “common failures
and analysis process of ABS”
△Notice the brake warning light will turn on during
parking brake process (when the switch is at “ON”
position) and when the brake fluid’s liquid sensor is
working

Use fault diagnosis instrument to check ABS control module

Use fault diagnosis instrument to check the data and failure code of control module, and repair the vehicle
according to the failure codes. Please refer to “failure diagnosis”

(IV) Torque parameter

No. Project

Torque （N·m）

Remark

1

Fixing bolt of speed sensor

8~10

2

Collar nut of brake pipe

16~18

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3

The bolt that connects ABS
controller and car body

20~25

(V) Maintenance precautions

During the maintenance of ABS and ESP, please pay attention to the following precautions, or they may
suffer unnecessary damages due to improper maintenance

1. Before undertake the electric welding, disconnect the connector assembly from ABS control module
2. The spare parts in ABS is very sensitive to EMI, please confirm that no interference exists in all
parts’ traces, position, installation, connectors and supports.
3. Do not use quick charger to start the engine or charge the battery which is connected to the engine,
because this will make battery invalid or cause damage to the spare parts in ABS.
4. Make sure the ignition switch be closed first, then disconnect the negative terminal of battery, and
disconnect the connector of ABS control module
5. Do not try to repair any spare parts in ABS, since all parts of ABS can only be replaced
6. Do not hang the suspension’s parts on the harness of speed sensor, in case of damage on sensor’s
harness.

7. The ABS control module cannot be placed under situation whose temperature is higher than 105 ℃.

8. Chlorine, sulphur and relevant inorganic substances cannot exist in brake circuit, nor the mineral oil
or ester/lubricant plasticizer, including parts that may ooze these kinds of substances.
9. During ABS operation, the brake pedal will vibrate mildly with mechanic noise. These are normal
circumstances.
10. When the ignition switch is turned to “ON” position and the car is started, the brake pedal may
vibrate, and the motor in ABS hydraulic assembly may make some noises. These are normal
circumstances during operation check.
11. When the vehicle is running on bumpy, sand or deep fresh-snow road, the brake distance may be
longer than vehicles without ABS.

(VI) Special tools

No.

Tools

Mechanical dimensions

Illustration

1

Fault diagnosis
instrument

ABS&ESP fault diagnosis

III Failure diagnosis

(I) Brief introduction of failure diagnosis

1). Failure diagnosis can thoroughly understand every
system of the vehicle

2). Understand the customer’s complaint before the check,
and inquire their dissatisfaction in detail after fighting out
the failure.

3). Make sure check the vehicle’s failure from the

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beginning in order to comprehensively repair the fault. For
intermittent failure, it is very important try to reappear the
failure according to the talk with customer and past cases.
Do not check under some special situations, as most
intermittent failures are caused by poor contacts. Under
this situation, swaying suspectable harness or connectors
with hands is an effective way.

4). After the diagnosis, be sure to “clear trouble codes”

(II) Fault diagnosis chart

Failure code chart for ABS

Trouble code

Failure illustration

C190104

Inadequate ECU’s voltage

C100004

Failure of ECU’s hardware

Failure diagnosis chart for ABS

No. Symptom

Analysis on symptom

Solutions

Remark

1 Cannot read the data stream

of ABS control module

Poor contact of diagnosis port

Check and connect

Please refer to
“diagnostic flow
chart of
unabling to read
ABS data
stream”

ABS control module unearthed

Check and replace

The battery hasn’t provided
voltage to ABS control module

Check and replace

The ignition switch hasn’t
provided voltage to ABS control
module

Check and replace

The data circuit is broken or in
short-cut

Check, connect or
replace

Excessive data circuit’s electric
resistance

Check and replace

2 ABS warning light cannot be

lighted

ABS warning light fails/socket
loosening

Check, connect or
replace

Please refer to
“diagnostic flow
chart of
unlighted ABS
warning light,
no trouble
codes”

Dashboard’s fuse broken

Check and replace

Drive module of dashboard’s
warning light fails

Check and replace

ABS control module fails

Check and replace

The circuit between dashboard
and ABS control module is broken
or in short-cut

Check, connect or
replace

3 ABS warning light keeps

lighting

Open circuit between dashboard
and ABS control module

Check and connect

Please refer to
“diagnostic flow
chart of ABS
warning light
keeps lighting,
no trouble

Short circuit between dashboard
and ABS control module

Check and replace

Drive module of dashboard’s
warning light fails

Check and replace