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Hyundai Getz>> Brake system>> Anti-blocking system of brakes (ABS)
Work principle
The anti-blocking system of brakes (ABS) serves for pressure regulation in brake mechanisms of all wheels when braking in difficult road conditions for prevention of blocking of wheels. The system provides:
– a detour of obstacles with higher degree of safety, including at emergency braking;
– reduction of a brake way at emergency braking with preservation of stability and controllability of the car, including in turn.
In case of malfunction of anti-blocking system function of diagnostics and emergency operation of work of system is provided.
The hydroelectronic control unit (GEBU) of anti-blocking system receives information on speed and the direction of movement of the car, and also on road conditions from sensors of speed of rotation of wheels.
On the basis of this information the control unit defines an optimum mode of braking of wheels.

Fig. 6.48. Elements of anti-blocking system of brakes: 1–hydroelectronic ABS (GEBU) control unit; 2–sensor of speed of rotation of a forward wheel; 3–sensor of speed of rotation of a back wheel; 4–control lamp of ABS and electronic system of distribution of brake forces; 5–diagnostic contact socket


Fig. 6.49. ABS hydrosystem: 1–brake pipeline of the right forward wheel; 2–brake pipeline of the left forward wheel; 3–brake pipeline of the right back wheel; 4–brake pipeline of the left back wheel; 5–brake hose of the right forward wheel; 6–brake hose of the left forward wheel; 7–brake hose of the right back wheel; 8–brake hose of the left back wheel; 9–hydroelectronic ABS (GEBU) control unit; 10-vacuum amplifier of brakes and main brake cylinder


Elements of anti-blocking system of brakes are shown on fig. 6.48 . The hydrosystem of anti-blocking system of brakes is presented on fig. 6.49 .

ABS management
Normal braking. At normal braking the electromagnetic valve is disconnected, the entrance valve is open, the target valve is closed. By pressing a brake pedal brake liquid under pressure moves in the wheel cylinder via the electromagnetic valve and puts a brake in action. At an otpuskaniye of a pedal of a brake brake liquid comes back to the main brake cylinder via the entrance valve and the return valve.
Operating mode. If at emergency braking blocking of a wheel begins, GEBU gives out command for reduction of supply of brake liquid on the electromagnetic valve, then tension moves on each electromagnetic valve. The entrance valve is closed, and supply of brake liquid in the main cylinder is blocked; the target valve opens, and brake liquid arrives via the wheel cylinder in a tank that causes pressure decrease.
Mode of maintenance of pressure. At the maximum pressure decrease in the GEBU wheel cylinder gives out on the electromagnetic valve command for maintenance of pressure of brake liquid, tension moves on the entrance valve and does not move on the target valve. Thus entrance and target valves are closed and brake liquid does not leave the wheel cylinder.
Mode of increase of pressure. If GEBU defines that the wheel is not blocked, it disconnects the electromagnetic valve. Tension on electromagnetic valves does not move, brake liquid via the entrance valve arrives in the wheel cylinder pressure in which increases.

Electronic system of distribution of brake forces (EBD)
The electronic system of distribution of brake forces (EBD) is a subsystem of ABS which serves for ensuring effective coupling of back wheels with a road surface.
Besides, the EBD system prevents blocking and drift of back wheels at partial modes of braking.
In the presence of system of distribution of brake forces the brake effort is supported near optimal to value and regulated by electronic system that allows to do without a usual regulator of pressure.
As a pressure regulator – the mechanical device, its possibilities are limited from the point of view of achievement of ideal distribution of brake forces between lobbies and back wheels, and also flexible distribution of brake forces depending on extent of loading of the car. Besides, malfunction of a mechanical regulator of pressure, as a rule, is not found by the driver.
The electronic system of distribution of brake forces (EBD) copes the ABS control unit. At movement the system of distribution of brake forces constantly defines
degree of a proskalzyvaniye of each of car wheels also regulates pressure of working liquid in brake mechanisms of back wheels so that it exceeded pressure in brake mechanisms of forward wheels.
In case of failure detection (tab. 6.1) of system of distribution of brake forces (EBD) in a combination of devices the control lamp of EBD (and the parking brake) lights up.

Table 6.1
Work of ABS and EBD systems at detection of malfunctions

Advantages of electronic system of distribution of brake forces is the following.
1. Improvement of work of the main brake system.
2. Compensation of a difference of factors of a friction (for each wheel of the car).
3. Lack of need for a traditional regulator of pressure.
4. The alarm system about malfunction by means of a control lamp on the dashboard.

Management of control lamps

Fig. 6.50. Control lamps of ABS and EBD


The arrangement of control lamps of ABS and EBD in a combination of devices is shown on fig. 6.50 .
Module of a control lamp of ABS. The control lamp of ABS shows degree of operability of ABS.
The control lamp lights up in the following cases:
– in an initialization phase after ignition inclusion (3 c);
– in case of a ban on ABS action at malfunction;
– if EBU does not join at the included ignition;
– in diagnostics mode.
Module of a control lamp of EBD. The control lamp of EBD shows degree of operability of EBD.
The control lamp lights up in the following cases:
– during an initialization phase after ignition inclusion (3 c);
– in case of a ban on EBD action at malfunction;
– if EBU does not join at the included ignition;
– at turning on of the parking brake or insufficient level of brake liquid.

       NOTE
Specified below the phenomenon are not signs of malfunction of ABS or EBD.

Features of work of ABS system
Sound at ABS system check. At engine start-up from a motor compartment deaf knock is sometimes audible. It is connected with check of operability of system.
Sound during ABS action. A sound of operation of the electric motor of the ABS hydroblock (a howling sound). The scraping sound accompanied by vibration of a pedal of a brake.
During ABS action from the chassis of the car there are sounds which are caused by repeating cycles of braking and a rastormazhivaniye of wheels (the bumps going from a suspension bracket; a scratch from tires).
Big brake way. On some pavings, including on snow-covered roads or a gravel covering, the brake way of the cars equipped with ABS, can be more usual. Therefore at movement on such roads the owner of the car should show care and to move on the lowered speed.
Vibration of a pedal of a brake is the normal phenomenon.
Codes of malfunction of ABS are specified in tab. 6.2.

Table 6.2
Codes of malfunctions of ABS of brakes

Fig. 6.51. Cable part of the socket of the hydroelectronic ABS control unit


The cable part of the socket of the hydroelectronic ABS control unit is shown on fig. 6.51 . Addressing of a cable part of the socket of the hydroelectronic ABS control unit is given in tab. 6.3.

Table 6.3
Addressing of contacts of the socket of the hydroelectronic control unit (GEBU) of ABS system
Number
contact
Address (purpose of contact)
The maximum
current
The minimum
current
Note
1
-
-
-

2
-
-
-

3
-
-
-

4
Control lamp of EBD
30 мА
5 мА

5
Diagnostics interface
6 мА
3 мА

6
Right forward wheel sensor
16 мА
6 мА

7
Right forward wheel sensor
16 мА
6 мА

8
Right back wheel sensor
16 мА
6 мА

9
-
-
-

10
Left back wheel sensor
16 мА
6 мА

11
Left forward wheel sensor
16 мА
6 мА

12
"Weight"
5-15 And
2,5 And
ABS management
13
Tension and / 1 (food лапанов)
5-15 And
2 And
ABS management
14
Tension and / 2 (electric motor food)
20-39 And
10 And
ABS management
15
"Weight"
20-39 And
10 And
ABS management
16
-
-
-

17
-
-
-

18
-
-
-

19
-
-
-

20
Control lamp of ABS
30 мА
5 мА

21
-



22
Switch of a signal of braking
10 мА
5 мА

23
Right back wheel sensor
16 мА
6 мА

24
Ignition
1 And
500 мА

25
Left back wheel sensor
16 мА
6 мА

26
Left forward wheel sensor
16 мА
6 мА


Removal and installation of elements of anti-blocking system of brakes
Hydroelectronic ABS control unit (GEBU)
Removal
Remove the air filter and an airintaking branch pipe.

Fig. 6.52. GEBU contact socket


Separate the GEBU contact socket (fig. 6.52)  with a double clamp, having pulled for it up.
Disconnect from GEBU brake pipelines.

Fig. 6.53. Bolts of fastening of an arm of GEBU (are specified by shooters)


Unscrew bolts  of fastening  of an arm  of GEBU and remove GEBU (fig. 6.53) .
The moment of an inhaling of bolts of fastening of an arm of GEBU – 8–10 N · m.

PREVENTIONS
Dismantling of GEBU is not allowed.
Transportation and GEBU storage in vertical situation with the muffled openings is allowed.
Do not merge liquid from GEBU.
Installation
GEBU installation carry out as it should be, the return to removal.
Tighten bolts of fastening of GEBU the moment of 8-10 N · m, the union of fastening of brake pipelines the moment of 13-17 N · m.
Check of tension of a signal of wheel sensors
Establish the car on the lift, switch off the parking brake.
Separate the GEBU contact socket and execute check on contacts of a cable part of the contact socket.

       NOTE
At check remove a double clamp of the contact socket and attach the control device to wires from outside, opposite to socket contacts. Accession measuring щупов the device to contacts does not provide reliable connection

By means of a tester or an oscillograph check tension of a signal of wheel sensors, rotating the corresponding wheel with a speed 0,5–1 with-1.
Connection of the control device for check of tension of a signal of wheel sensors       
Wheel sensor   of Number of contacts of the socket
The left forward.............. 11, 26
The right forward............ 6, 7
The left back.................. 10, 25
The right back................ 8, 23
Tension of a signal at measurement by means of an oscillograph, In:
bottom level..... 0,535 (at a current 7 мА)
top level..... 1,050 (at a current 14 мА)

Sensors of speed of rotation of wheels

Fig. 6.54. Sensor of speed of rotation of a forward wheel: 1–contact socket of the sensor of speed of rotation of a forward wheel; 2–sensor of speed of rotation of a forward wheel


Fig. 6.55. Sensor of speed of rotation of a back wheel: 1–sensor of speed of rotation of a back wheel


The sensor of speed of rotation of a forward wheel is shown on fig. 6.54 , a back wheel – on fig. 6.55 .
Removal of the forward wheel sensor

Fig. 6.56. Bolt of fastening of the forward wheel sensor


Unscrew a bolt of fastening of the forward wheel sensor (fig. 6.56) .
In a motor compartment separate the contact socket of the forward wheel sensor.
Remove elements of fastening of conducting of the wheel sensor (see fig. 6.54 ).
Remove the wheel sensor.
Removal of the back wheel sensor
Separate the contact socket of the back wheel sensor on a wheel nave (see fig. 6.55 ).
Remove a brake drum, having unscrewed the screw of its fastening to a wheel nave.
Unscrew four bolts of fastening of a nave of a back wheel to a beam of a back suspension bracket.

Fig. 6.57. Removal of a nave of a back wheel


Remove a nave of a back wheel via the brake mechanism (fig. 6.57) .

PREVENTION
Do not remove the wheel sensor from a nave in hammer blows as it can lead to a sensor exit out of operation.

Air removal from a hydraulic actuator of brakes 
Operation is carried out for effective removal of air from a hydraulic actuator of brakes and filling with brake liquid of the hydraulic block of anti-blocking system of brakes, brake pipelines and the main brake cylinder.
For air removal from a hydraulic actuator of brakes of the cars equipped with anti-blocking system, the diagnostic HI-SCAN device is used. At carrying out this operation the device connected to the diagnostic socket under the dashboard, operates electromagnetic valves and the electric pump
anti-blocking system.
Remove a stopper of a tank of a hydraulic actuator of brakes and fill a tank with brake liquid.
For a dolivka use only brake DOT-3 or DOT-4 liquid.

PREVENTION
At hit of brake liquid on a paint and varnish covering of a body immediately wash away it a large amount of water.

       NOTE
When using special installation for removal of air do not press a brake pedal.

Attach a transparent plastic hose to the pumping union on the wheel cylinder and lower other end of a hose in the transparent capacity half filled with brake liquid.
Attach the HI-SCAN device to the diagnostic socket located under the dashboard.
By means of the HI-SCAN device turn on the electropump and electromagnetic valves of anti-blocking system.
Execute operations as directed, displayed the HI-SCAN device.

PREVENTION
For prevention of a peregoraniye of windings of the electric motor of the pump of anti-blocking system do not exceed the most admissible time of its work specified on the screen of the HI-SCAN device.

Several times press a brake pedal, opening the pumping union until in following liquid air vials then tighten the pumping union will cease to appear.
Execute the described operation on other wheels of the car in the following order: a back right wheel (in the direction of movement of the car), a forward left wheel, a back left wheel, a forward right wheel.
Moment of an inhaling of unions of pumping of 7-13 N · m.