Haima S5 1.5T. Chassis System. Service Manual - part 5

 

Brake system 2F-14 

 

2.  Step down the brake pedal with a force of 

196N {20kgf}. 

3.  Keep stepping down the brake pedal. When 

the reading of vacuum gauge is up to 66.7kPa 
{500mmHg}, stop the engine. 

4.  Observe the vacuum gauge for 15s. If the 

vacuum pressure indicates 63.3-66.7kPa 
{475-500mmHg}, it indicates the normal 
operation of vacuum booster. 

Check of hydraulic system 

1.  Stop the engine (vacuum pressure of 

0kPa{0mmHg}. If the pressure of fluid is 
within the specified range at this time, it 
indicates the normal operation of vacuum 
booster. 

Pedal pressure 

Fluid pressure 

196N{20kgf} 586kPa{6kgf/cm

2

}min 

 

2.  Start the engine. When its vacuum pressure 

reaches 66. 7kPa{500mmHg}, step down the 
brake pedal. 

  If the pressure of fluid is within the specified 

range at this time, it indicates the normal 
operation of brake device. 

 

Pedal pressure 

Fluid pressure 

196N{20kgf} 9003kPa{92kgf/cm

2

}min

 

Vacuum hose assembly 

Vacuum hose assembly (1.6L engine) 

Note: vacuum tube containing internal one-way 
valve

.

 

Removal procedures : 

1.  With a pair of pliers or a special tool clamp 

release clamps ②, respectively ③ vacuum 
booster hose assemblies removed from the 
engine vacuum suction port and the vacuum 
booster interface ① Department; 

2.  Use tools to remove the bolts ④ from the 

vacuum booster hose assembly bracket; 

3.  Take down the vacuum hose.  

 

 

Installation procedures : 

1.The use of tools by bolts ④ the vacuum booster    

hose assembly bracket to the engine lug 
Department; 

2. With a pair of pliers or a special tool through 
hoop clamp ②, respectively connection, attention 
should be solid and reliable work clamp booster 
vacuum hose assembly ③ and engine vacuum 
suction port and the vacuum booster interface ① 
Department. 

 

Vacuum hose assembly (1.5T engine) 

Note: 1. Vacuum tube containing internal one-way 

valve

. 

           2. 1.5T vacuum models span, need two parts 

removal and installation. 

 

Removal procedures : 

1.With a pair of pliers or a special tool clamp 

release clamps ①,  ② the vacuum booster hose 
pulled from the front engine vacuum suction 
mouth; 

 

Brake system 2F-15 

 

2.With the tools to remove the bolts and bolt ③ ④, 

the vacuum booster hose ② removed from the 
front of the engine and gearbox hanging on the 
ear; 

3.With a pair of pliers or a special tool clamp 

release clamps ⑤, the anterior posterior segment 
of the vacuum booster hose and vacuum booster 
hose ② ⑥ separately; 

4.Remove the vacuum booster hose front ②; 

5.With a pair of pliers or a clamp release clamps 

⑦

 special tools and clamps, the segment inlet ⑧ 

⑥

 take place and electric vacuum from the 

vacuum booster pump booster hose inlet take 
place to remove; 

6.With tools to remove the bolts, remove the upper 

section of the body right stringer ⑥ booster 
vacuum hose; 

7.The first double pipe clamp ⑨ ⑥ removed from 

the segment after the vacuum booster hose, and 
then removed from the segment ⑥  ⑩ double 
pipe clamp booster vacuum hose; 

8. Remove the vacuum booster hose ⑥ segment. 

Installation procedures : 

1.With the tool through bolt and bolt ③ ④ booster 

vacuum hose ② front lug the engine and 
gearbox are connected; 

2.  ①  ② front of the vacuum booster hose and 

engine vacuum suction port connected through a 
hoop clamp with pliers or special tools; 

3.After the vacuum booster hose attached to the 

double pipe clamp ⑥  ⑩ on, and then double 
pipe clamp attached to the segment ⑨  ⑥ 
vacuum booster hose to enhance fixed; 

4.With the tools bolts vacuum booster hose and 

electric vacuum pump ⑥ take air intakes 
connected; 

5.With a pair of pliers or a special tool through 
hoop clamp ⑤, ⑦ clamps and clamp, respectively, 
after the section of the vacuum booster hose and 
vacuum booster hose ⑥ front ②, take the vacuum 
booster inlet ⑧ and electric vacuum pump inlet to 
take place connection, attention to clamp work to 
be solid and reliable. 

Electric vacuum pump 

Electric vacuum pump (1.5T engine only) 

Removal procedures : 

1.With a pair of pliers or a special tool clamp 

release clamps ⑤, is the vacuum booster 
vacuum hose and electric separation; 

 

2．The electric pump wiring harness plug from the 

electrical connection on the pump mounting 
bracket ③ removed; 

3.Using tools from the electric vacuum pump to 

remove the mounting bolts ②; 

4. Remove the vacuum hose. 

 

Vacuum booster assembly 

Removal procedures: 

1. First remove the master cylinder brake hard pipe, 

oil pipe connected to the master cylinder and 
booster vacuum hose and master cylinder with a 
plug to seal the oil port; 

2. Unplug cotter pin ③, remove the pin ②, remove 

the nut with a tool ⑤; 

3. Vacuum booster assembly is removed with 

vacuum booster and master cylinder mounting 
bracket; 

4. Use the tool to remove the nut ⑦, the vacuum 

booster assembly with vacuum booster and 
master cylinder mounting bracket separation. 

 

Brake system 2F-16 

 

 

 

Installation procedures : 

1. First use of nuts with a master cylinder and 

vacuum booster assembly vacuum booster 
mounting brackets together, tighten the nut 
torque of 23N • m. 

2.Vacuum booster assembly and vacuum booster 

with master cylinder mounting bracket through 
the body using a nut and the brake pedal, the nut 
tightening torque of 23N • m. 

3. The booster pedal pusher fork arm connecting 

hole pairs, the insert pin, cotter pin lock. 

4. Master cylinder brake hard pipe, drip tubing 

master cylinder and vacuum booster hose 
connected to the vacuum booster, master 
cylinder brake hardware fittings tightening 
torque for M10 16.2N • m, M12 18.2N • m. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Brake system 2F-17 

 

Front and rear brakes 

General and operation  

Brake caliper assembly 

This brake caliper is a single-cylinder one installed 
on the steering knuckle with two bolts. The 
hydraulic force produced by brake pedal is 
converted into braking force. This braking force 
equally acts on the piston and bottom of caliper 
chamber to make the piston move out and brake 
caliper slide in, thus an action to clamp the brake 
disc is produced, which makes the brake liner affix 
the brake disc, and produces a frictional force to 
stop the vehicle. 

 

Note:  

During the replacement of brake caliper, please 
replace all the components. 

Lubricate the rubber parts with clean brake fluid 
for easier assembling. 

Don’t apply the lubricated compressed air to avoid 
the damages of rubber parts. 

Once the hydraulic elements are removed or 
separated, it’s required to exhaust the brake system. 

The brake liner of front brake assembly must be 
replaced in sets. 

The tightening torque is only applicable for dry or 
unlubricated fasteners. 

Repair them with clean or unpolluted wrench. 

Return clearance 

When the hydraulic pressure acts on the piston, the 
piston moves to left. At this time, the seal ring 
produces a large pressure to the piston, so it moves 
with the piston. However, the part of seal ring is 
fixed in the ring groove of brake caliper as shown 
in the figure. When the piston moves to left, the 
seal ring will be torsioned and deformed. 

After the hydraulic pressure is released, the elastic 

force stored in the seal ring makes the piston move 
to right and return to its initial position. When the 
piston moves, the brake liner will move with it, 
and the clearance between brake disc and liner will 
be gradually increased. 

After the friction block is worn, the clearance 
between the brake disc and friction block will be 
increased, and the piston stroke will be also 
increased. The seal ring has a certain deformation, 
but after its deformation exceeds the certain value, 
the seal ring will move the groove of inner end of 
cylinder body, and the elastic deformation of seal 
ring will have the specified limit. 

After the clearance is increased, the piston is 
required to move a more distance to eliminate the 
clearance. When the piston returns, its return 
stroke keeps unchanged, and the seal ring will also 
return to its initial shape, so the clearance between 
the brake disc and friction block will keep its 
initial state unchanged. 

 

 

Check of front-disc brake 

Hints for brake judder repairs  

The brake judder problems have the following 
three features: 

1.  Vibration of steering wheel: this feature is 

the most obvious when it’s braked at 100 to 
140 km/h {62 to 87 mph} if the steering 
wheel vibrates in its rotation direction; 

2.  Vibration of floor: the vehicle body shakes 

forward and back, its shaking level is not 
influenced by the vehicle speed; 

3.  Vibration of brake pedal: an impulse force 

trys to push the brake liner, and this impulse 
is transmitted to the brake pedal during the 
braking operation. 

The following are several main reasons to make 
the brake shake: 

Piston 

Brake disc 

Friction block 

1. Piston 
2. Piston seal ring 
3. Friction block 
a.Clearance 

 

Brake system 2F-18 

 

1.  Excessive jumps of brake disc, the swing 

thickness from one side to other side is 
uneven: 

At the place 10 mm {0.39in} away from the edge 
of brake disc, if its jump exceeds 0.05mm {0.002 
in}, it indicates that the uneven wears of disc are 
caused by uneven contact of liner and disc. If its 
jump is below 0.05mm {0.002in}, it indicates that 
no uneven wears occur. 

2. 

Thermal deformation of disc:  

Repeated violent braking operations can make the 

local temperature of disc rise up to about 
1,000 {1

℃

,832ºF}, thus it will lead to the 

deformation of disc. 

3.  Due to the changes of corroded disc 

thickness and friction coefficient: 

If the vehicle parks in wet environment for a long 
time, the friction surface of disc will be corroded, 
its uneven corrosion thickness is sometimes like 
corrugations, its friction coefficient will be 
changed and produce a reaction force. 

Procedures for check and repair 

 

Check of transverse jump 

1.  Tighten the hub nut diagonally, and ensure 

the correct installation of disc and hub, or 
insert the washer between the hub bolt and 
hub nut. 

The thickness of washer is 10mm {0.39 in} and its 

inner diameter is over 12mm{0.47 in}. 

2.  After tightening all the hub nuts up to the 

same torque, place a dial indicator on the 
friction surface of brake disc in the position 
about 10mm{0.39in}away from the edge of 
disc. 

3.  Turn the brake disc once and measure its 

transverse jump. 

Its jump limit: 0. 05mm{0. 002 in}. 

 

Check of its thickness changes 

1.  Clean the friction surface of brake disc and 

brake liner with a brake cleaner. 

2.  Measure the thickness of each point shown in 

Certify the customer0’s 

Peform the transverse jump test. (refer 
to the transverse jump test)

Above 0.05mm {0.002in} 

Below 0.05mm 

{0.002in} 

Below 

0.05mm 

{0.002in}

Appear 

Disappear 

Confirm whether the 
brake shakes

Above 0.015mm {0.0005in} 

Below 0.015mm {0.0005in} 

Above 

0.05mm 

{0.002in}

Confirm remove the disc, install it 
in other phase position, and re-
perform the transverse jump test. 
Whether the brake shakes 

Perform the thickness change 
test (see below) 

Certify the repair conditions. 

Machine the disc with an on-
board grinder

Tighten all the hub nuts up to the 
same torque to fix the brake disc, 
and measure its transverse jump. 

Grind with an on-board grinder (below 
0.015mm{0.0005in}). 

Completion of work. 

 

Brake system 2F-19 

 

the figure with a caliper dial indicator. 

3.  Deduct the minimum value with the measured 

maximum value. If the result can’t meet the 
requirements, machine the brake disc with a 
grinding tool. 

Its thickness change limit: 0.015 mm {0.0005 in} 

Warning: 

• Don’t exceed the minimum thickness of brake 
disc. 

Thickness check of front or rear brake disc 

1.  Measure the thickness of brake disc. 

Caution: 

If the brake disc is removed from the vehicle for 
machining, it may cause its excessive jump. 
Therefore, it’s required to be machined when the 
brake disc is installed on the vehicle. Minimum 
thickness: front disc: 26mm {1.02 in}. Adopt its 
minimum thickness machined on the vehicle: 24. 8 
{0. 94in} 

2.  If the thickness of brake disc is not within the 

technical requirements, replace the brake disc. 

Warning: 

 

Don’t exceed the minimum thickness of 

brake disc. 

Check of brake liner thickness 

1.  Jack up the front of vehicle, and support it 

with a safety support. 

2.  Remove the wheel. 

 

3.  Check the residual thickness of liner, and 

replace the sets of liners. Provided the 
thickness of one side liner of left and right 
wheels is equal to or below its minimum 
thickness, it’s required to replace left and 
right liners at the same time. Thickness of 
liner: minimum value 2. 0mm { 0. 08in}. 

4.  If the thickness of any side of left or right 

wheel is below or equal to its minimum 
thickness, replace the brake shoes from its 
both sides. 

Removal and installation of Front-disc 
brake 

1.  For its removal and installation, refer to the 

figure. 

2.  After installing it, step the brake pedal several 

times, and turn the wheel by hands to confirm 
the existence of brake drag. 

Table I: List of supply-level parts for front steering 
knuckle with brake assembly 

 

1 

Caliper support bolt 

2 

Front brake caliper assembly(left/right) 

3 Front 

brake 

disc 

4 

Front outer friction plate 

5 

Front inner friction plate (left/right) 

6 

Steering knuckle assembly(left/right) 

Table 

II: Removal of front-disc brake assembly

 

 

Removal of front-
disc brake assembly

 

Brake system 2F-20 

 

1 Brake 

hose 

2 

Hollow bolt（22-29N.m）  

3 Sealing 

washe

r

 

4 

Shaft pin bolt （30-36N.m） 

5 Caliper 

assembly 

6 

Inner and outer friction plate assembly  

7

Cotter pin 

8

Lock nut 

9

Brake disc 

10

Caliper support bolt (160-170N.m) 

 

 

 

 

 

 

 

 

Keypoints for removing the brake disc 

1.  Before removing it, make the marks on the 

hub bolt and brake disc for the references 
of installation.  

 

Keypoints for installing the brake disc 

1.  Remove any rust or dust from the contact 

surface of brake disc and hub. 

2.  Assemble the brake disc by aligning to the 

mark before removing it. 

 

Keypoints for installing the brake liner 

1.  Push the piston to bottom with SST. 

2.  Install the brake liner. 

 

 

 

 

Replacement of front brake liner 

1.  Remove it in the sequence shown in the 

table. 

2.  Install it in the reverse sequence of 

removal. 

1 Bolt 

2 Support 

bracket 

3 Circlip 

4 Guide 

pin 

5 

Guide pin dust cover 

6 

Inner and outer friction plates 

Disassembly and assembling of front brake 
caliper 

1.  Disassemble it in the sequence shown in 

the table. 

2.  Assemble it in the reverse sequence of 

removal. 

Mark 

Wood 
board 

 

Brake system 2F-21 

 

 

 

1 

Dustproof seal ring 

2 

Piston(refer to keypoints for 
disassembling P piston) 

3 

Piston seal ring (refer to keypoints for 
disassembling P piston seal ring) 

4 

Bleed screw cover 

5 Bleed 

screw 

6 brake 

caliper 

body 

 

 

 

Keypoints for disassembling the piston 

Note: 

 While blowing the compressed air into brake 
caliper, blow it slowly to avoid the sudden jump 
of piston. 

Place SST inside the brake caliper, blow the 
compressed air from the hole into brake caliper, 
to make the piston push into the brake caliper. 

 

 

 

 

 

Keypoints for disassembling the piston seal 
ring 

Take the brake caliper out of piston seal ring 
with SST. 

 

 

Rear brake disc with drum brakes  

Thickness check of brake shoe friction plate 

1.  Remove the observation hole blockage 

observed thickness of the brake shoe. 

2.  Check the thickness of residual friction 

plates. Provided the thickness of any of left 
and right friction plates is equal to below 
its minimum thickness, replace left and 
right brake shoes at the same time. 

Thickness of friction plate 

Its minimum value of 1.0 mm {0.04 in} 

 

Brake system 2F-22 

 

 

 

 

 

Check of brake drum 

1.  Measure the inner diameter of brake drum.

Maximum value of inner diameter 

172 mm {6.77 in} 

 

  2.  If necessary, repair or replace the brake 

drum. 

3.  Check whether the contact of drum and 

brake shoe is good when repairing or 
replacing the brake drum. 

 

 

Friction brake shoes and brake drum 
clearance check 
Friction brake shoes and brake drum design 
clearance gap 0.3-0.5 mm {0.011 in-0.02 in}. 
When the gap please exceeds the design value 
of the parking brake adjustment screw assembly 
adjustments. 

Table 1:  

Brakes with rear drum brakes dismantling chart 

 

 

1 Lock 

bolt 

2 Rear 

brake 

caliper 

3 Rear 

brake 

discs 

4 Lock 

bolt 

5 Hub 

Bearing 

Unit 

6 Lock 

bolt 

7 Rear 

parking 

brake 

 

Removing and installing rear drum brakes 
with brake 

1. Remove and install the chart below. 

2. After installation, use the following steps to   
adjust the cable: 

1) 294N (30Kg, 66 lb) force operating the  

parking handle more than 10 times. 

2) Turn the adjusting nut with a ratchet wrench 

to adjust the parking lever stroke. 

3) Check the parking lever stroke and the 

operating force. 

4) 245N force operating the parking lever 

handle to check whether a predetermined stroke 
range of the notch (9-11 teeth). 

5) Turn the brake disc in the case of the 

parking lever is released, and check the drag. 

 

 

 

 

 

 

 

 

Brake system 2F-23 

 

Table II: The parking brake is split Parts List

 

1 Clip 

2 Locating 

Pins 

3 

Upper tension spring (left) 

4 

Upper tension spring (right) 

5 

Adjusting screw rod assembly 

(left /right) 

6 

Lower tension spring 

7 

Push plate (left and right) 

8 

Parking brake shoe assembly 

(right) 

9 

Parking brake shoe assembly 

(left ) 

10

Lever (left / right) 

11

Parking brake plate (left/right) 

 

 

 

Check of rear-disc brake 

Hints for repair of brake tremor  

(refer to front-disc brake); 

Thickness check of rear brake disc 

1.  Measure the thickness of brake disc. 

Note: 

If the brake disc is removed from the vehicle for 
machining, it may cause its excessive jump. 
Therefore, it’s required to machine during the 
installation of brake disc on the vehicle. 

 

 

  Minimum thickness: rear disc: 9mm {0.35in} 

Adopt the minimum thickness machined on the 
vehicle: 8.8 {0.35in} 

2. If the thickness of brake disc is not within the 
technical requirements, replace the brake disc. 

Warning: 

  Don’t exceed the minimum thickness of 

brake disc.  

Thickness check of brake liner 

1.  Jack up the front of vehicle with a jack, and 

tie it firmly with a safety support. 

2.  Remove the wheel. 

3.  Check the residual thickness of liner, and 

replace the liner in sets. Provided the 
thickness of any block of left and right 
wheels is below or equal to its minimum 
thickness, it’s required to replace left and 
right liners at the same time. 

Minimum thickness of rear liner: 2.0 mm {0.8in}

4.  If the thickness of any side of left and right 

wheels is below or equal to its minimum 
thickness, replace both brake shoes in sets. 

 

 
 

 

Brake system 2F-24 

 

 

Keypoints for removing the brake disc:  

Before removing the disc, make the marks on 

hub bolt and brake disc for the references of 
installation. 

Keypoints for installing the brake disc 

a.  Remove any rust or dust from the contact 

surface of brake disc and hub. 

b.  Align the mark made before the removal, 

and assemble the brake disc. 

 

Removal and installation of rear service 
brakes 

1.Instructions for removal of rear brake lining

a.  Remove it in the sequence of installation; 

b.  Install it in the reverse sequence of removal.

 

 

 

 

 

 

 

2.Instructions for installing rear brake linings 

a.  Push in the piston fully with SST; 

b.  Install the brake shoe. 

1.  Description of caliper body disassembly 

 

(refer to the description of front caliper 

disassembly) 

 

1 

Piston sealing ring (see P piston 
seal disintegration points) 

2 

Piston (see P piston disintegration 
points) 

3 Dust 

seals 

4 Brake 

caliper 

bracket 

5 Dust 

Cover 

6 

Outer friction plate assembly 

7 Circlip 
8 

Inner friction plate assembly 

9 Clamp 

body 

10

Guide pins 

11

Bleeder screw 

12

Bleeder screw cap 

 

Mark

 

Brake system 2F-25 

 

Parking brake system  

General and operation 

It’s displayed through the parking brake caution 
light

installed on the instrument panel. When 

the ignition switch is turned on, the caution light 
goes on. When the parking handle is put down, the 
caution light goes out. Whenever the parking 
control mechanism is pulled, when the ignition 
switch is turned, the caution light should be on. 

Structure diagram 

Parking brake 

 

1. Parking 

brake 

handle 

2.     Lock nut 

3.     Front cable assembly 

4.  Parking brake cable (right) 

5.  Parking brake handle fixing bolt 

6.  Parking brake cable (left) 

7.  Parking brake cable fixing bolt 

Repair instructions 

Parking brake handle and front cable assembly 

1.  Remove the parking brake handle cover of 

auxiliary instrument panel(a) (see the details 
of auxiliary instrument panel removal 
method). 

 

2.  Remove the wire plug ②  of brake lamp 

switch on parking handle . 

3.  Place the parking brake handle in loosened 

position, loosen and remove three fixing bolts
③

 of parking brake handle, and the tightening 

torque of bolt during the assembly:19 to 
25N.m. 

 

 

4. Loosen the cable assembly before ④ self-

locking nuts, relax before cable assembly, rear 
parking  ⑤⑥ connector cable assembly cable 
assembly removed from the front slot. 

5. Remove the front cable assembly ④ from the 

parking brake lever assembly ②, remove the 
parking brake lever assembly ② from the body. 

 
Rear parking brake cable assembly 

1. Disconnect the cable assembly before and after 

parking the connection cable assembly in 
accordance with the demolition, "parking brake 
lever and cable assembly before" in the method, 
and then the rear parking cable ② mounting 
bracket from the body detached. 

 

2. Use a tool to remove the body from the 

fastening bolts ① ② and rear bracket supports 
④

. 

Tightening torque bolt assembly is: 15 ~ 

 

Brake system 2F-26 

 

19N.m 

3. Use the tool to remove the fastening bolts from 

the rear bracket arm ④ ⑤ 
When mounting bolt tightening torque is: 18 ~ 
26N.m

 

 

Check of handle parking brake  

1.  Pull the parking brake handle several times. 

2.  Step the brake pedal several times. 

3.  Pull the parking brake handle with a force of 

245N {25kgf, 55Ibf}, and check the stroke of 
parking brake. 

Stroke of 9-11 teeth. 

Adjustment of parking brake handle stroke 

1.  Adjust the clearance of brake shoe. 

2.  Start the engine, and step the brake pedal 

several times. 

3. Stop 

the 

engine. 

4.   Turn the parking handle ① and ③ connect 

cable assembly before adjusting nut ②, pull 
the handle to test its stroke. 

 

5.  After adjusting it, check the following points: 

(1)  Turn the ignition switch, pull the parking 

brake handle by 1 tooth, and confirm that the 
parking brake lamp goes on. 

(2)  Confirm no brake drag of rear brake. 

 

Parameters 

General technical parameters 

Item Instructions 

Stroke of parking brake handle  9 to 11 teeth[tensile force of 245N (25 kgf, 55 Ibf)] 

 Locking torque parameters 

Item Nm 

Lb-Ft 

Lb-in 

Parking handle mounting nut 

22 

- 

89 

Parking cable fixed support 

mounting bolt 

17 - 

69 

 

Brake system 2F-27 

 

 

ABS system 

Note: when moving or installing other electronic elements, or tools and other equipment are easy to contact 
the exposed terminals, disconnect the power cathode lines. It can avoid the personal injury and vehicle 
damages to disconnect this wire. The ignition switch must be also in B gear, unless otherwise marked 
additionally. Don’t diagnose ABS system, because it will lead to the termination of ABS functions. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Overview  

I. Attentions 

ABS is a part related to the safety. Therefore, the 
following attentions for diagnosis must be also 
followed in addition to general safety and 
preventive measures during its repair diagnosis. 

1.  ABS system must be repaired by trained and 

skilled technicians, and can be replaced only by 
the original part. 

2.  Before diagnosing ABS system, if the 

fundamental brake system has any fault, first 
remove it, e.g.: 

● 

Brake system noises 

 

 

 

 

Brake system 2F-28 

 

● Overhard 

brake 

pedal. 

●  During the common braking operation, The 

brake pedal or vehicle vibrates. 

● 

Runout of vehicle brake. 

● 

Faults of parking brake system 

      

 

3.  ABS assembly (e.g. ABS electronic control 

unit and hydraulic regulator assembly, 
excluding the brake pipe, sensor or other 
auxiliary devices) can be only replaced as a 
whole, and can’t be disassembled for check 
or partially replaced/interchanged. Bosch 
doesn’t supply any separate spare part, and 
doesn’t guarantee the disassembled ABS 
assembly, and undertake no responsibility for 
bad consequences caused after disassembling 
or partially replacing/interchanging ABS 
hydraulic regulator. 

4.  The following two cases indicate that ABS 

system detects the faults: 

●  After turning on the ignition switch, the self-

check of system is finished, and the warning 
lamp keeps lightened. 

●  While the vehicle is driving, the warning lamp 

keeps constantly on. At this time, the driver can 
apply the regular braking operation, but he 
should try his best to reduce the applied 
braking force, and prevent the wheel from 
locking. After the warning lamp goes on, it’s 
required to drive carefully and go to the special 
service station immediately for repair, so as to 
avoid the occurrence of more accidents, 
otherwise it will lead to the traffic accidents. 

5.  The following points need to be attentioned 

while connecting ABS sensor wires: 

●  Before pulling ABS wire and sensor wire, be 

sure to disconnect the ignition switch. 

●  Ensure the drying and cleanness of connector, 

and avoid the entry of any strange substance . 

● 

The connectors of ABS wires must be installed 

        in position in horizontal and vertical directions 

to avoid their damages. 

6.   While connecting ABS brake pipes, be sure to   

ensure their correct installation. ABS ECU 
can’t judge whether the brake pipes are 
correctly connected. Any wrong connection 
may lead to the serious accident. During the 
connection of brake pipe, be sure to follow the 
mark on ABS assembly: 

●  MC1: connect the brake master cylinder brake 

pipe 1; 

●  MC2: connect the brake master cylinder brake 

pipe 2; 

●  FL: connect the brake pipe of left front wheel 

brake wheel cylinder; 

● 

FR: connect the brake pipe of right front wheel 
brake wheel cylinder; 

●  RL: connect the brake pipe of left rear wheel 

brake wheel cylinder; 

●  RR: connect the brake pipe of right rear wheel 

brake wheel cylinder. 

 

 

7.  ABS will produce the noises in the following 

cases: 

●  After powering on the vehicle or starting the 

engine, it will produce a short sound of “buzz”, 
this is a sound of ABS self-check, which is a 
normal phenomenon. 

●     ABS will produce the noises during the

 

normal

 

 

Brake system 2F-29 

 

 

operation, which is mainly reflected by the 

following aspects: 

1)  Action sound of motor, solenoid valve and 

return pump in ABS hydraulic unit. 

2)  Sound caused by the bounce of brake pedal. 

3) 

Impact sound of suspension and body 

caused by emergency braking operation. 

 

 

II. Initial 

check 

Before the diagnosis of ABS system, first check its 
parts, which may cause the faults of ABS system 
and be easy to contact, their visual check and 
appearance check procedures can determine the 
faults quickly, thus their further diagnosis need’s be 
diagnosed. 

1.  Ensure that only the tires and hubs with 

recommended sizes are installed on the vehicle. 
The patterns and depths of tires on the same 
shaft must be the same.  

For the details of tire models, please refer to the 

operating instructions for vehicle. 

2.  Check ABS hydraulic regulator, brake pipe and 

connection for leakage. 

3.  Check the fuses of ABS system, ensure that no 

fuses are burnt and their models are correct. 
ABS system has three fuses separately: 

  　Pump motor fuse(40A) 

  　Solenoid valve fuse(25A) 

  　Electronic control unit fuse (10A) 

4.  Check the voltage of battery, and check 

whether the battery terminals are corroded or 
loosened. Normal operating voltage range of 
ABS system is 9. 3V-16. 8V. 

5.  Check whether the bonding point of ABS earth 

wire is loosened, and whether its earthed 
position is changed. 

 

 

 
 
 
 

 

 

6.  ABS earth wire must have good sealing ability 

to prevent the water or moisture from 
penetrating into ABS ECU joint through the 
hole of wire due to capillary effect (siphon), 
thus it can lead to the failure of its function. 
Adopted measures: apply the seal gum to 
exposed ends of wire, and adopt the shrinkable 
tube gland. 

7.  Apply the visual checks and appearance checks 

of the following electric parts: 



Whether the wires and connectors of relevant

 

Apply the seal gum to the exposed end of wire, 
and adopt the shrinkable tube gland. 

Ignition 

coil/ignition 

wire/spark plug

Gear ring

Generator

 

Wheel speed sensor

 

Water 

line