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11-8
ESP OFF switch
Located on the left side of
instrument panel.
Rear wheel speed sensor
Located on the both ends of
rear axle.Front wheel speed sensor
Located on the hub
assembly.Sensor cluster
Located at the bottom of
center fascia panel.
Steering wheel angle sensor
Located on column shaft with
contact coil.HECU assembly
Located near the brake
booster in engine
compartment and contains
the pressure sensor.
2. COMPONENTS
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11-114890-10
2) EBD (Electronic Brake-force Distribution) Warning Lamp (Brake
Warning Lamp)
EBD warning lamp when the system perform 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 disengaging the connector, 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.
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. 6.
3) ESP OFF Indicator
ESP OFF indicator ON:
When turning the ignition switch to ON position, ESP warning lamp comes on for 3 seconds for
self diagnosis and goes off if the system is OK (initialization mode).
When the ESP OFF switch is pressed to turn off ESP function, ESP OFF indicator comes on. 1.
2.
4) ESP Warning Lamp
ESP warning lamp ON:
When turning the ignition switch to ON position, ESP 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 ESP function is activated, ESP warning lamp blinks with the interval of 2 Hz.
When the communication between warning lamp CAN module in meter cluster, the warning
lamp comes on. 1.
2.
3.
4.
5.
5) ESP OFF Switch
If ESP OFF switch is pressed, ESP function is deactivated and the ESP OFF indicator in the
instrument cluster comes on.
To resume the ESP function, press the switch again. At this time, ESP OFF indicator goes out.
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11-16
4) HBA (Hydraulic Brake Assist System)
(1) Purpose
HBA (Hydraulic Brake Assist) system helps in an emergency braking situation when the driver
applies the brake fast, but not with sufficient pressure, which leads to dangerously long braking
distance. ECU recognizes the attempt at full braking and transmits the signal calling for full brake
pressure from the hydraulic booster. An inexperienced, elderly or physically weak driver may suffer
from the accident by not fully pressing the brake pedal when hard braking is required under
emergency. The HBA System increases the braking force under urgent situations to enhance the
inputted braking force from the driver. Based on the fact that some drivers depress the brake
pedal too soft even under when hard braking is necessary, the HECU system is a safety
supplementary system that builds high braking force during initial braking according to pressure
value of the brake pressure sensor and the pressure changes of the pressure sensor intervals.
When the system is designed to apply high braking force when brake pedal is depressed softly by
an elderly or physically weak driver, the vehicle will make abrupt stopping under normal braking
situation due to high braking pressure at each wheels.
(2) Operation
The brake pressure value and the changed value of the pressure sensor are the conditions in
which the HBA System operates. There are 2 pressure sensors under the master cylinder. When
the ESP ECU system determines that emergency braking is present, the pump operates, the
brake fluid in the master cylinder is sent to the pump and the braking pressure is delivered to the
wheels via the inlet valves . If the drive depress the brake pedal slowly, the pressure change is not
high. In this case, only the conventional brake system with booster is activated.
(3) Operating conditions
Sensor pressure: over 40 bar
Pressure changes: over 850 bar/sec
Vehicle speed: over 30 km/h -
-
-
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5) ARP (Active Roll-Over Protection
The ARP (Active Roll-over Protection) system is a safety assistant device that minimizes, by
controlling brakes and the engine, the physical tendency of the vehicle rollover during sharp lane
changes or U-turns. For the system, software is added to the existing ESP system and no
additional device or switch is needed. One must note that the ARP system, just as general
assistant devices including the ABS, is only a safety assistant device using the ESP system and its
function is useless when the situation overcomes the physical power. Following picture shows
how the ARP compensates the vehicle position by varying each wheel's braking power to
overcome the physical tendency of the vehicle rollover during sharp turns.
Lateral sensor
(In sensor cluster)
Vehicle speedBrake force
Radius
The vehicle driving condition is controlled by the internally programmed logic according to the
input signals from wheel speed sensor, steering angle sensor and lateral sensor.
During the ARP operation, vehicle safety (rollover prevention) takes the first priority and thus,
stronger engine control is in effect. Consequently, the vehicle speed decreases rapidly, so the
driver must take caution for the vehicle may drift away from the lane.
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5) Hydraulic Circuit of HBA
The above figure shows one front and one rear wheel and the same hydraulic circuit forms as in
the ESP operation. When HECU recognizes that it is an emergency and it is required for hard
braking, depending on the pressure value of the brake pressure sensor and pressure changes
caused by the pressure sensor timing, it operates the pump immediately to apply the brake
pressure at the wheels. Then, the pressure in the pump increases until just before the
corresponding wheel gets locked. The motor still keeps rotating and the outlet valve and the
separation valve will stay closed. When the wheel starts to lock, the HBA function cancels and
switches to ABS operation.
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