0-26
REXTON 2006.09
4892-01
CIRCUIT
Specifications
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C. HBA (HYDRAULIC BRAKE ASSIST SYSTEM)
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 unde
urgent situations to enhance the inputted braking force from the driver.
D. SWAS : STEERING WHEEL ANGLE SENSOR
The steering wheel angle sensor is located between clock spring and multifunction switch.
This sensor is used for recognition of driver’s intends. If the sensor is replaced with
new one, it can detect the neutral position after the vehicle is moving over 20 km/h for more
than 5 seconds.
E. HDC (Hill Descent Control) SYSTEM
When the slope level exceeds 10%, the HDC operates until the vehicle reaches the speed
condition given in step (4).
When the slope level is between 10% and 20% during the HDC operation
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When depressing the accelerator pedal or brake pedal, HDC system is changed to
stand-by mode. When depressing the accelerator pedal again, HDC starts its operation
again. Therefore, drivers can control the vehicle speed to a desired level by operating
the accelerator pedal.
When the slope level exceeds 20% during the HDC operation
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When depressing the accelerator pedal, HDC system is changed to stand-by mode.
When depressing the brake pedal, HDC continues its operation and the braking power is
increased. In this case, HECU sounds an abnormal noise and brake pedal may be very
rigid, but this is a normal condition due to HDC operation.
(3) CIRCUIT DESCRIPTION
A. ABS COMPONENTS
Newly introduced ABS has a different shape of integrated hydraulic modulator and HECU
(Hydraulic and Electronic Control Unit) compared to existing ABS. And, the wheel speed
sensor uses different method to detect wheel speed. The basic function of the ABS that
maintains the vehicle stability by controlling the steerability of the vehicle when braking has
not been changed.
B. ACTIVE WHEEL SPEED SENSOR
The speed sensor used in traditional ABS is made of permanent magnet and transmits the
output voltage that changes as the wheel rotor rotates to the HECU system. New wheel
speed sensor detects the wheel speed through the current value that depends on the
resistance that changes according to the magnetic field by using four resisters and supplying
the 12 V power supply to the sensor.