Hyundai Santa Fe (2006 year). Manual — part 251
BR -176
BRAKE SYSTEM
INSPECTION
EC6A680F
1.
Measure the output voltage between the terminal of
the wheel speed sensor and the body ground.
CAUTION
In order to protect the wheel speed sensor, when
measuring output voltage, a 75Ω resistor must be
used as shown.
Power
Ground
DC 12V
R(75
Ω
)
Oscilloscope
Tone wheel
Wheel sensor
Vin
Vout
EJRF501Z
2.
Compare the change of the output voltage of the
wheel speed sensor to the normal change of the
output voltage as shown below.
V
V
high
V
low
0V
t
KJQE260B
• V_low : 0.44 V ~ 0.63 V
• V_high : 0.885 V ~ 1.26 V
• Frequency range : 1~2,500 Hz
EBD (ELECTRONIC BRAKE-FORCE DISTRIBUTION)
BR -177
EBD (ELECTRONIC
BRAKE-FORCE
DISTRIBUTION)
DESCRIPTION
E747F93F
The EBD system (Electronic Brake force Distribution) as
a sub-system of the ABS system is to control the effective
adhesion utilization by the rear wheels.
It further utilizes the efficiency of highly developed ABS
equipment by controlling the slip of the rear wheels in the
partial braking range.
The brake force is moved even closer to the optimum and
controlled electronically, thus dispensing with the need for
the proportioning valve.
The proportioning valve, because of a mechanical device,
has limitations to achieve an ideal brake force distribu-
tion tothe rear wheels as well as to carry out the flexible
brake force distribution proportioning to the vehicle load
or weight increasing. And in the event of malfunctioning,
driver cannot notice whether it fails or not.
EBD controlled by the ABS Control Module, calculates the
slip ratio of each wheel at all times and controls the brake
pressure of the rear wheels not to exceed that of the front
wheels.
If the EBD fails, the EBD warning lamp (Parking brake
lamp) lights up.
ADVANTAGES
-
Function improvement of the base-brake system.
-
Compensation for the different friction coefficients.
-
Elimination of the proportioning valve.
-
Failure recognition by the warning lamp.
COMPARISON BETWEEN PROPORTIONING VALVE AND EBD
[With P-Valve]
[With EBD]
Fixed distribution
Ideal distribution
Cut-in point
Rear pressure
Front pressure
Rear pressure
Front pressure
Ideal distribution
EBD starting point
EJA0032A
BR -178
BRAKE SYSTEM
ESP/ESC SYSTEM
DESCRIPTION OF ESP
E1A8FE6B
Optimum driving safety now has a name : ESP, the Elec-
tronic Stability Control.
ESP recognizes critical driving conditions, such as panic
reactions in dangerous situations, and stabilizes the ve-
hicle by wheel-individual braking and engine control in-
tervention with no needfor actuating the brake or the gas
pedal.
ESP adds a further function known as Active Yaw Control
(AYC) to the ABS, TCS, EBD and ESP functions. Whereas
the ABS/TCS function controls wheel slip during braking
and acceleration and, thus, mainly intervenes in the longi-
tudinal dynamics of the vehicle, active yaw control stabi-
lizes the vehicle about its vertical axis.
This is achieved by wheel individual brake intervention and
adaptation of the momentary engine torque with no need
for any action to be taken by the driver.
ESC essentially consists of three assemblies : the sen-
sors, the electronic control unit and the actuators.
Of course, the stability control feature works under all driv-
ing and operating conditions. Under certain driving condi-
tions, the ABS/TCS function can be activated simultane-
ously with the ESP function in response to a command by
the driver.
In the event of a failure of the stability control function, the
basic safety function, ABS, is still maintained.
Driving force control
Brake force control
ESP
Yaw-moment
Control
ESP
Drift-out
Control
E
S
P
E
S
P
LJCD201A
ESP/ESC SYSTEM
BR -179
DESCRIPTION OF ESP CONTROL
ESP system includes ABS/EBD, TCS and AYC (Active yaw
control) function.
ABS/EBD function : The ECU changes the active sensor
signal (current shift) coming from the four wheel sensors to
the square waveform.By using the input of above signals,
the ECU calculates the vehicle speed and the acceleration
&
deceleration of the four wheels.And, the ECU judges
whether the ABS/EBD should be actuated or not.
TCS function prevents the wheel slip of drive direction by
adding the brake pressure and engine torque reduction via
CAN communication.TCS function uses the wheel speed
sensor signal to determine the wheel slip as far as ABS
function.
AYC function prevents unstable maneuver of the vehicle.
To determine the vehicle maneuver, AYC function uses the
maneuver sensor signals(Yaw Rate Sensor, Lateral Accel-
eration Sensor, Steering Wheel Angle Sensor).If vehicle
maneuver is unstable (Over Steer or Under Steer), AYC
function applies the brake pressure on certain wheel, and
send engine torque reduction signal by CAN.
After the key-on, the ECU continually diagnoses the
system failure.
(self-diagnosis)If the system failure is
detected, the ECU informs driver of the system failure
through the BRAKE/ABS/ESP warning lamp.
(fail-safe
warning)
ESP
HECU
Master cylinder
Pressure sensor
Master
cylinder
Steering wheel
Angle sensor
Yaw-rate &
lateral acceleration
sensor
Wheel speed
sensor
Wheel speed
sensor
EJRF502K
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