HYUNDAI AERO TOWN D6DA 2010 hệ THỐNG PHANH ANTI LOCK BRACKE general

General

ABS Function
Under rapid braking or sloppy road condition by rain or snow, braking a vehicle in running is apt
to generate skid condition. The skid may decrease braking force to increase braking distance,
generate spin by traverse slipping, and/or disable steering control, resulting to an accident.
Therefore the ABS system is designed to prevent from wheel locking and slip upon braking for
ensuring :
1 Stability,
.
2.Steer ability, and
3 Optimum braking power and stopping distance.
. Skid : A vehicle may slip to move without wheel rotation upon braking.
Slip rate (λ)
Upon braking a vehicle which is running, slip rate changes from 0 to 100% until the wheels are
locked and the vehicle stops completely. The slip rate l may be indicated as the below :
λ = Vehicle speed － Wheel speed / Vehicle speed × 100(%)
The slip rate (λ) and the surface friction coefficient (μB) may be correlated as the illustration.
The slip rate (λ) at the max.mB differs by the road condition but the max. range is approx,
8~30%. The cornering force (transversely slip preventing force) decreases with increasing slip


rate. Once wheels are locked, surface friction coefficient μB decreases and slip friction
coefficient μS becomes to '0', and then wheels are easy to slip.
In fact locked rear wheels generate spinning and locked front wheels disables steer ability. The
ABS system controls braking force to maintain the slip rate in the range of 8~30%, in order to
generate max. surface friction coefficient, control slip friction coefficient at higher range, and
provide stability and steer ability.
ABS Effect
The ABS system provides stable braking under extreme condition. Even braking rapidly on
frozen or snowy road, wheels are not locked and maintain max. friction with the road surface to

provide optimum braking distance. Restricting the pressure in the chamber locked at the wheel
side on the road surface, the system ensures straight forward motion. The driver may acquire
correct alignment of the vehicle by adjusting the steering wheel only a little.
ABS configuration

Full air brake


Air over hydraulic brake


Principle


Parts functions


1 Wheel speed sensor
. The 4-channel ABS uses four wheel speed sensors. The sensor consists of a permanent magnet
connected to metal rod, around which a coil has been wound. A pulse wheel mounted to the
hub induces an alternating voltage in the sensor coil. The frequency of the alternating voltage
is managed signal in the control unit.
2.ABS/ASR control unit
The ABS/ASR control unit is designed in digital type and possess dual microprocessors, with
the following four features:
(1)Input stage
The unit checks the wheel speed signal
(2)Computer
The computer calculates the brake slip/traction and wheel deceleration/wheel acceleration
control signal, and energize the output stage when wheels are about to be locked or spin.

(3)Output stage
The unit energizes interface and axle weight distribution unit for controlling the pressure
control valve, the solenoid valve, and the engine.


(4)Power supply
The unit supplies stable voltage for the control unit operation. The built-in protective
device prevents electrical interference from applying to the vehicle electrical circuit.
3 Pressure control valve (1 channel)
. Each wheel is not controlled by a 1 channel control valve. The pressure control valve includes
two diaphragm type valves (for pressure modulation, and for outlet) that are guided and
controlled by the solenoid valves. Upon normal braking, compressed air freely pass through the
pressure control valve to the brake cylinder. If one of wheels is about to be locked, the
ABS/ASR control unit energizes both solenoid valves to lower the pressure in the brake
cylinder. The pressure modulation valve operates to modulate the pressure. When the pressure
is rising no current flows in the two solenoid valves.

4.Solenoid valve
The solenoid valves are connected with two 3/2 solenoid valves that are pilot-controlled. When
wheel's are about to spin, the valve energizes the axle brake cylinder driven by compressed air.
Two control plungers are controlled by the solenoid valves.
When current is interrupted, power supply 1 is close and the cylinder connections are open
outwards.


ABS control


When the drive press the brake pedal, the pressure is supplied to the brake cylinder (or air
chamber), and result to wheel deceleration. When the brake slip is lower than the ABS system

reaction limit value, the braking power is not controlled. The ABS/ASR valve rises. In order to
provide the most proper pressure in the brake cylinder, the pressure decreases, is maintained, or
increases in accordance with friction coefficient between tires, road surface, and vehicle steering.
The illustration 6 indicates the ABS control feature on wheels upon braking. At time t1, the
pressure in the brake cylinder increases and the wheel speed decreases. At time t2, the wheel
deceleration and the slip rate increase above the limit, and the wheel is about to be locked. With
closing the pressure modulation valve and opening the exhaust valve, the pressure in the brake
cylinder increases until the wheel speed increases again at time t3. Closing the exhaust valve, the
pressure is maintained at a certain level to time t4. Then the slip value l =0 approximately, and
the wheel acceleration reached the value that may raise the pressure again. Then instantly
opening and closing the pressure modulation valve, the pressure becomes pulse-up until time t5.
The wheel deceleration and slip is higher than the limit again, and the pressure rise again. The
control cycle repeats until the vehicle stops actually.
Yaw moment on the front axle
When the friction coefficients are significantly different between right and left wheels (for
example when the road is frozen at outer side), corrective control feature is applied to the front
axle accommodating between short braking distance and steering corrective value. Constraining
pressure rising and braking force on wheels, the yaw moment is restricted within the range that
vehicle control is possible under rapid braking condition.
Friction force between tire and surface
Friction force between tires and road surface when other conditions are same, friction forces
between tires and road surfaces are virtually same for starting and braking conditions. Friction
force measurement (friction coefficient) differs by road condition, weather condition, tread type,
and especially braking and wheel slip. (Refer to illustration 7). In usual, braking motive force is
within the stable area of slip curve. In general rapid braking increases brake slip and decrease
friction force. With higher brake slip, wheels have lower traverse force for stability and steer
ability of the vehicle.
The ABS system is designed primarily for stability and steer ability of the vehicle. Friction force
on running as well as on braking relies particularly on slip between tires and road surfaces. With
higher wheel slip, traction and running stability decreases. With lowest wheel friction,

differential function provides driving power.


performance when there are faults present
Speed sensor
System configuration : Air over hydraulic brake
ABS control

Failure

WL

Front left

Front
right

Front left speed sensor

NO¹

IC

IC

IC

ON

Front right speed sensor

IC

NO¹

IC

IC

ON

Rear left speed sensor

SL

SL

NO

IC

ON

Rear right speed sensor

SL

SL

IC

NO

ON

Mixed up speed sensors

NO

NO

NO

NO

ON

Tire size, alignment error

NO

NO

NO

NO

ON

Two speed sensor errors or one

speed sensor error and one PMV
error

NO

NO

NO

NO

ON

IC : individual control

Rear left Rear right


SL : Select low
WL : Warning lamp
1) Brake pressure is modulated according to behavior of not affected wheel.
System configuration : Full air brake
ABS control

Failure

WL

Front left

Front
right

Front left speed sensor

NO¹

IC¹

IC

IC

ON

Front right speed sensor

IC¹

NO¹

IC

IC

ON

Rear left speed sensor

MIC

MIC

NO

IC

ON

Rear right speed sensor

MIC

MIC

IC

NO

ON

Mixed up speed sensors

NO

NO

NO

NO

ON

Tire size, alignment error

NO

NO

NO

NO

ON

Two speed sensor errors or one
speed sensor error and one PMV
error

NO

NO

NO

NO

ON

Rear left Rear right

IC : individual control
SL : Select low
MIC : Modified individual control
1) MIC if affected wheel is on high m side.
PMV errors
System configuration : Full air brake
ABS control

Failure

WL

Front left

Front
right

Valve solenoid front left shorted
low or broken wire or valve ground
front left broken wire

NO

IC

IC

IC

ON

Valve solenoid front right shorted

IC

NO

IC

IC

ON

Rear left Rear right


low or broken wire or valve ground
front right broken wire
Valve solenoid rear left shorted low
or broken wire or valve ground rear
left broken wire

MIC

MIC

NO

IC

ON

Valve solenoid rear right shorted
low or broken wire or valve ground
rear right broken wire

MIC

MIC

IC

NO

ON

Any valve solenoid or valve ground
shorted high

NO

NO

NO

NO

ON

Valve ground shorted low

MIC

MIC

IC

IC

ON

Two valve error or one valve error
and one speed sensor error

NO

NO

NO

NO

ON

System configuration : Air over hydraulic brake
ABS control

Failure

WL

Front left

Front
right

Valve solenoid front left shorted
low or broken wire or valve ground
front left broken wire

NO

NO

IC

IC

ON

Valve solenoid front right shorted
low or broken wire or valve ground
front right broken wire

SL

SL

NO

IC

ON

Valve solenoid rear right shorted
low or broken wire or valve ground
rear right broken wire

SL

SL

IC

NO

ON

Any valve solenoid or valve ground
shorted high

NO

NO

NO

NO

ON

Valve ground shorted low

SL

SL

IC

IC

ON

Two valve error or one valve error
and one speed sensor error

NO

NO

NO

NO

ON

Rear left Rear right

Power supply errors

ABS control

Failure
Front left

Front

Rear left Rear right

WL


right
GND shorted high or broken wire

NO

NO

NO

NO

ON

U_PMV or U_ECU over voltage or
low voltage¹

NO

NO

NO

NO

ON

U_PMV or U_ECU broken wire

NO

NO

NO

NO

ON

1 : Errors are reversible (can reast) provided they do not occur during ABS cycles.
Miscellaneous errors
ABS control

Failure

WL

Front left

Front
right

NO

NO

NO

NO

ON

Internal relay always ON

YES¹

YES¹

YES¹

YES¹

ON

RET shorted high or shorted low or
broken wire

YES¹

YES¹

YES¹

YES¹

ON

CAN interface bus off

YES¹

YES¹

YES¹

YES¹

ON

CAN interface error on message
ERC1

YES¹

YES¹

YES¹

YES¹

ON

Internal ECU failure or internal
relay switch failure

Safety monitoring

Rear left Rear right


1 Safety monitoring
. The ABS system satisfies highest safety and reliability requirements. Prior to starting the
vehicle, microcomputers perform self-diagnosis and check other computers, and then monitor
wheel spin sensor, pressure modulation valve, wiring harness, and the whole ABS system.
Finding a failure the ABS system becomes wholly or partly inoperable and the warning lamp
comes on. The service brake system is still operable.
2.Self-diagnostic feature
In addition to the safety monitoring system, the self-diagnostic feature built in the ABS control
unit enables to remove the failure immediately and safely. Upon failure detection by the ABS
control unit, the failure code is stored in the computer that may be read later at a service shop.
Then temporary failures including poor contraction at plug connection may be found and
eliminated soonest.

3 How to read the failure code
. Failure codes may be read using a Hi-scan and self-diagnosis by blink signals of the lamp.
Self-diagnosis on a vehicle
1 ABS lamp
. When a problem occurs in using the ABS system, the red ABS lamp comes on for warning in order to
facilitate finding the trouble area by self-diagnosis.

In normal condition, the ABS lamp comes on upon switching the battery power on and extinguished upon
starting the vehicle and during running. If a trouble occurs in the ABS system during running, the ABS lamp


comes on even or running.

2.Diagnostic method
The blink code device reads out error codes of 16 systems that are stored in the ECU system
configuration and error memory. The device checks the brake signal, as well.
The blink codes may be read using the ASR lamp, and troubles read with the self-diagnostic
button may be identified using the blink code table.
3 Blink code configuration
. In order to operate the blink code, keep the self-diagnostic button pressed for two seconds and then release it.
Pressing the button once it will indicate the system configuration and an error code. Press the self-diagnostic
button once again to read error codes.
The ASR lamp indicates an error code each time pressing the button.
After reading out all error codes stored in the memory using the blink codes, the last stored code may be read
continually.
Quitting self-diagnosis for 5minutes or more, or switching the starting key off and on again, the selfdiagnostic feature reads all information again from the beginning, the system configuration.
Each error code including the brake signal failure, includes three blocks.
The first block may be read at 100's digit, the second block at 10's digit, and the third block at 1's digit.

4.Failure memory erasion
Then ABS ECU will erase all error codes when the diagnostic push button is pressed during power on.


5.Safety measure
Upon ABS failure

Failed circuit

Operate as a non-ABS brake

Other circuits

ABS operation

At least the ABS system may operate just same as a non-ABS brake.
Hi-scan check
1 Turn the starting key off.
.
2.Connect a Hi-scan with the data link connector located under the low crash pad panel.
3 Turn the starting key on.
.
4.Using the Hi-scan, check DTCs.
5.Upon repairing or correcting the problem, turn the starting switch and clear stored error codes
using the clear key.
6 Disconnect the Hi-scan.
.