SSANGYONG KORANDO 2013 Service Manual

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1. SYSTEM OVERVIEW
1) What is ABS?
When braking suddenly or braking on slippery roads, the vehicle keeps moving forward but the wheels
are locking and not rotating. If these happen, the vehicle may lose stability or rotate resulting in an
accident. ABS helps to maintain directional stability and control of the vehicle. ABS is designed to
secure more safety and increase the control of steering wheel during emergency braking situation. But,
ABS does not guarantee perfect safety beyond its physical limit. ABS in this vehicle contains EBD
function. In normal driving conditions, the brake system operates without ABS function.
2) What is EBD (Electronic Brake-force Distribution)?
EBD is an automobile brake technology that automatically varies the amount of force applied to each of a
vehicle's brakes, based on road conditions, speed, loading, etc. Always coupled with anti-lock braking
systems, EBD can apply more or less braking pressure to each wheel in order to maximize stopping
power whilst maintaining vehicular control. EBD does not operate when ABS is working. ABS effect according to braking conditions
Braking on split road Maneuvering while braking

3. G-sensor (for 4WD)
Located on the floor under
parking brake bracket in center
console.4. Rear wheel speed sensor
(for 2WD)
Located on knuckle. The
appearance is different from that
for 4WD.4. Wheel speed sensor
(for 4WD)
Located on knuckle. The
appearance of front sensor is
same with rear sensor.
2. ABS warning lamp
EBD warning lamp (ABS warning lamp +
Brake warning lamp)1. ABS hydraulic device and control unit
Located under the power steering fluid reservoir and
contains the pressure sensor.
2. COMPONENT

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4WD - Front/Rear wheel speed
sensor
2WD - Front wheel speed sensor
2WD - Rear wheel speed sensor
ECU (Electronic Control Unit) 1.
ECU calculates the wheel speed, acceleration and
deceleration with the information from wheel
speed sensor, and determines the wheel slip to
control the valve and motor.
HU (Hydraulic Unit) 2.
The hydraulic circuit contains the primary circuit
and secondary circuit for ABS operation. This unit
controls the hydraulic pressure to each wheel. If
the system needs ABS operation, the valves in
the unit operate to control HOLD, RISE and
DUMP according to ECU control logic.
Motor 3.
The motor is operated when ABS is activated. The
cam-shaped output shaft of the motor enables the
brake system to receive and supply the brake fluid
during the motor operation.
Wheel speed sensor
Wheel speed sensor sends the data detected by
tone wheel to HECU.
HECU
Rear wheel speed sensor in 2WD vehicle is
different from that in 4WD vehicle.
Location of rear tone wheel (A) and wheel
sensor (B) in 2WD vehicle

G-sensor (only for 4WD)
For the vehicle with the ABS, a speed difference
between the wheels is not noticeable as all the
wheels are slipping during abrupt braking.
Therefore, the vehicle needs the speed
information from other sensors other than the
wheel speed sensor. On the 2WD vehicle, there
is not large difference between the vehicle speed
reduction and actual wheel speed reduction in
the event of braking since the driving wheels are
in the front. So, the ABS HECU can control the
vehicle, based on a calculation value. But, on the
4WD vehicle, if a speed reduction occurs in the
front or rear of the vehicle, it affects the other side
wheel. In other words, braking the rear wheels
induces also a large speed reduction in the front
wheels. The longitudinal acceleration sensor is
used for this case. It controls the ABS by using
the signals from the sensor during abrupt braking
and acceleration.
G-sensor

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3. ABS CONTROL LOGIC
The principal ABS control logic is the determination of the reference speed by choosing one wheel
meeting a certain condition, while sensing the speed information from 4 wheel speed sensors when the
vehicle is being driven.
For example, when the comparison of the reference speed with front right wheel speed shows a slip, the
control signal is determined according to whether it's deceleration or acceleration. If the control
conditions are met, the brake for the front right wheel will be got under control.

4. WARNING LAMPS
1) ABS Warning Lamp
ABS warning lamp module indicates the self diagnosis and malfunction.
ABS warning lamp ON:
When turning the ignition switch to ON position, ABS warning lamp comes on for 3 seconds for self-
diagnosis and goes off if the system is OK (initialization mode).
When the system is defective, the warning lamp comes on.
When the self-diagnosis is performing, the warning lamp comes on.
When the HECU connector is disconnected, the warning lamp comes on.
ABS is not available during lamp ON. In this condition, Only normal brake system without ABS function
is available.
When the communication between warning lamp CAN module in meter cluster, the warning lamp
comes on. 1.
2.
3.
4.
5.
6.
ABS warning lamp
Brake warning lamp
(EBD warning lamp: ABS warning lamp + Brake warning lamp) 1.
2.

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2) EBD (Electronic Brake-force Distribution) Warning Lamp (Brake
Warning Lamp)
EBD warning lamp when the system performs the self diagnosis and when it detects the malfunction of
EBD system. However, the brake warning lamp comes on regardless of EBD when the parking brake is
applied.
EBD warning lamp ON:
When turning the ignition switch to ON position, ABS warning lamp and the brake warning lamp
comes on for 3 seconds for self diagnosis and goes off if the system is OK (initialization mode).
When applying the parking brake, the brake warning lamp comes on.
When the brake fluid is not sufficient, the brake warning lamp comes on.
When the self-diagnosis is performing, the warning lamp comes on.
When the HECU connector is disconnected, the warning lamp comes on.
When the system is defective, ABS warning lamp and the brake warning lamp come on
simultaneously. 1.
2.
3.
4.
5.
6.
When the solenoid valve is defective
When one or more wheel sensors are defective
When ABS HECU is defective
When the voltage is abnormal
When valve relay is defective a.
b.
c.
d.
e.
When the communication between warning lamp CAN module in meter cluster, the warning lamp
comes on. 7.

5. SYSTEM OPERATION
1) Block Diagram of ABS HECU

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2) Basic Theory of ABS Function
To give you a better understanding of the tasks and functions of ABS, we will first look at the physics
principles.
(1) Stopping distance
The stopping distance depends on the vehicle weight and initial speed when braking starts. This also
applies for vehicle with ABS, where ABS always tries to set an optimum brake force on each wheel. As
great forces are exerted between the tires and the carriageway when braking, even with ABS the wheels
may scream and rubber is left on the road. With an ABS skid mark one may be able to clearly recognize
the tire profile. The skid mark of an ABS vehicle does not however leave any hint of the speed of the
vehicle in the case of an accident, as it can only be clearly drawn at the start of braking.
(2) Brake force on a wheel
The maximum possible brake force on a wheel depends on the wheel load and the adhesion coefficient
between tire and carriageway. With a low adhesion coefficient the brake force, which can be obtained is
very low. You are bound to know the result already from driving on winter roads. With a high adhesion
coefficient on a dry road, the brake force, which can be obtained, is considerably higher. The brake
force, which can be obtained, can be calculated from below formula:
Maximum brake force
FBmax = wheel load FR x coefficient of frictionMh
The braking process cannot be described sufficiently
accurately with the brake forces calculated. The
values calculated only apply if the wheel is not locked.
In the case of a locking wheel, the static friction turns
into lower sliding friction, with the result that the
stopping distance is increased. This loss of friction is
termed "slip" in specialist literature.

Slip
The brake slip is the difference between the vehicle speed and the wheel circumference speed. If the
wheel locks, the slip is greatest, that is 100 %. If the wheel is running freely and un-braked, the slip is the
lowest, equal to 0 %. Slip can be calculated from the vehicle speed Vveh and the wheel speed Vw. The
equation for this is:
Vveh = 100 km/h, Vw = 70 km/h
Slip ratio (S) =
For the various road conditions, the friction
coefficients were plotted. The typical course of
the curves is always the same. The only special
feature is shown by the curve for freshly fallen
snow, for this curve increases at 100 % slip. In a
vehicle without ABS, the wheel locks on braking
and therefore pushes a wedge before it. This
wedge of loose surface or freshly fallen snow
means and increased resistance and as a result
the stopping distance is shorter. This reduction in
stopping distance is not possible with a vehicle
with ABS, as the wheel does not lock. On these
surfaces the stopping distance with ABS is
longer than without ABS. The reason for this is
based in physics and not in the Anti-Lock
System.
However, as mentioned before, ABS is not about
the stopping distance, but maneuverability and
driving stability, for the vehicle with locking
wheels without ABS cannot be steered. Typical Slip Curves
Vveh - Vw
VvehX 100%
S = 30%