| VERACRUZ(EN) >2013 > G 3.8 DOHC > Brake System > ESC(Electronic Stability Control) System>Description and Operation |
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Optimum driving safety
now has a name : ESC, the Electronic Stability Control.
ESC recognizes
critical driving conditions, such as panic reactions in dangerous
situations, and stabilizes the vehicle by wheel-individual braking and
engine control intervention with no need for actuating the brake or the
gas pedal.
ESC adds a further
function known as Active Yaw Control (AYC) to the ABS, TCS, EBD and ESC
functions. Whereas the ABS/TCS function controls wheel slip during braking
and acceleration and, thus, mainly intervenes in the longitudinal dynamics
of the vehicle, active yaw control stabilizes 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 sensors, the electronic control unit
and the actuators.
The stability control
feature works under all driving and operating conditions. Under certain
driving conditions, the ABS/TCS function can be activated simultaneously
with the ESC 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.
Description
of ESC Control
ESC system includes
ABS/EBD, TCS and AYC function.
ABS/EBD function : The
ECU changes the active sensor signal (current shift) coming from the four
wheel sensors to the square wave.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
Acceleration 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/ESC warning lamp. (fail-safe warning)
Input
And Output Diagram
ABS
Control
ESC
HECU External Diagram
Hydraulic
System Diagram
ABS
Warning Lamp Module
The active ABS warning
lamp module indicates the self-test and failure status of the ABS .The ABS
warning lamp shall be on:
EBD/Parking
Brake Warning Lamp Module
The active EBD warning
lamp module indicates the self-test and failure status of the EBD.
However, in case the Parking Brake Switch is turned on, the EBD warning
lamp is always turned on regardless of EBD functions. The EBD warning lamp
shallbe on:
ESC
OFF Lamp (ESC System)
The ESC OFF lamp
indicates the OFF status of the ESC system.
The ESC OFF lamp is
turned on under the following conditions :
ESC
Function Lamp (ESC System)
The ESC function lamp
indicates the self-test and operating status of the ESC.
The ESC Function lamp
operates under the following conditions :
ESC
On/Off Switch (ESC System)
The ESC On/Off Switch
shall be used to toggle the ESC function between On/Off states based upon
driver input.
The On/Off switch
shall be a normally open, momentary contact switch.Closed contacts switch
the circuit to ignition.
Initial status of the
ESC function is on and switch toggle the
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