Page 327 of 364

DESCRIPTION OF CONSTRUCTION AND OPERATION
ACTIVE STABILITY CONTROL SYSTEM (ASC)35C-17
DESCRIPTION OF CONSTRUCTION AND OPERATION
M2357000600037
Stability control operation
•ASC-ECU receives various kinds of information
from the wheel speed sensor, steering wheel
sensor, G and yaw rate sensor, pressure sensor,
stop lamp switch, brake fluid level switch, parking
brake switch, and engine ECU. When ECU deter
-
mines the vehicle runs in the oversteer or unders-
teer direction based on the signal sent from these
sensors, ASC-ECU drives each valve and pump
motor and controls the braking force to be applied
to the wheels.
•When the system increases the fluid pressure
automatically, it closes the cut valve to shut off
the pressure line to the suction valve, and drives
the pump motor. For example, when the vehicle
runs in the oversteer direction while turning to the
right, ASC-ECU supplies the brake fluid from the
pump to the front left wheel in order to apply the
braking force on it.
•ASC-ECU and the engine ECU communicate
with each other via CAN communication. When
the accelerator pedal is depressed too far, the
signal requesting the engine output reduction is
sent to the engine ECU so that the ASC controlla
-
bility can be secured.
Page 328 of 364
DESCRIPTION OF CONSTRUCTION AND OPERATION
ACTIVE STABILITY CONTROL SYSTEM (ASC)35C-18
When the brake fluid pressure is increased at ABS deactivation (normal brake
control)/ABS activation (Example: When the front-left/rear-right wheel system
pressure is increased)
AC600863 AB
MP
Master cylinder
Cut valve
Motor Inlet valve (RR)
Outlet valve
(RR)
Wheel cylinder (RR) Hydraulic unit
Pressure sensor
Suction valve
Pump Inlet valve
(FL)
Outlet valve (FL)
Wheel cylinder (FL)
The fluid p r essure ge nerated from the maste r cylin-
de r is supplied to each wheel cylinder through the cut
valve an
d outlet valve (FL/RR).
VA L VE CONDITION
ItemPower statusOpen/Close
Suction valveOFFClosed
Cut valveOFFOpen
Inlet valve (FL)OFFOpen
Inlet valve (RR)OFFOpen
Outlet valve (FL)OFFClosed
Outlet valve (RR)OFFClosed
Page 329 of 364
DESCRIPTION OF CONSTRUCTION AND OPERATION
ACTIVE STABILITY CONTROL SYSTEM (ASC)35C-19
When the brake fluid pressure is held by the ABS control/stability control (Example:
When the front-left/rear-right whee l system pressure is held)
AC600863
AC
MP
Master cylinder
Cut valve
Motor Inlet valve (RR)
Outlet valve
(RR)
Wheel cylinder (RR) Hydraulic unit
Pressure sensor
Suction valve
Pump Inlet valve
(FL)
Outlet valve (FL)
Wheel cylinder (FL)
By closing the inlet va lve (FL/RR) and o u tle t valve
(FL/RR), the br
ake f l uid pressure in the wh eel cylin
-
der can be main t a ined.
VA L VE CONDITION
ItemPower statusOpen/Close
Suction valveOFFClosed
Cut valveOFFOpen
Inlet valve (FL)ONClosed
Inlet valve (RR)ONClosed
Outlet valve (FL)OFFClosed
Outlet valve (RR)OFFClosed
Page 330 of 364
DESCRIPTION OF CONSTRUCTION AND OPERATION
ACTIVE STABILITY CONTROL SYSTEM (ASC)35C-20
When the brake fluid pressure is reduced by the ABS control/stability control
(Example: Front-left/rear-right wheel system)
AC600863 AD
MP
Master cylinder
Cut valve
Motor Inlet valve (RR)
Outlet valve
(RR)
Wheel cylinder (RR) Hydraulic unit
Pressure sensor
Suction valve
Pump Inlet valve
(FL)
Outlet valve (FL)
Wheel cylinder (FL)
The out let valve (FL/RR) is ope ned to drive the
pump
, and th e brake fluid in the wh eel cylinde r is
returned
to the master cylinder so tha t the fluid level
in the
wheel cylinde r is reduced.
VA L VE CONDITION
ItemPower statusOpen/Close
Suction valveOFFClosed
Cut valveOFFOpen
Inlet valve (FL)ONClosed
Inlet valve (RR)ONClosed
Outlet valve (FL)ONOpen
Outlet valve (RR)ONOpen
Page 331 of 364
DESCRIPTION OF CONSTRUCTION AND OPERATION
ACTIVE STABILITY CONTROL SYSTEM (ASC)35C-21
When the brake fluid pressure is increased by the TCL control/stability control
(Example: When the front-left whee l system pressure is increased)
AC600863
AE
MP
Master cylinder
Cut valve
Motor Inlet valve (RR)
Outlet valve
(RR)
Wheel cylinder (RR) Hydraulic unit
Pressure sensor
Suction valve
Pump Inlet valve
(FL)
Outlet valve (FL)
Wheel cylinder (FL)
The in let valve (RR) is clo s ed to prevent th e brake
fluid
pressure from b e ing applied to the whee l cylin
-
der (RR). The suction valve an d inlet va lve (FL) are
opened
to drive t he pump, which supplies the bra k e
fluid
from the maste r cylind e r to th e wheel cylin der
(FL).
VA L VE CONDITION
ItemPower statusOpen/Close
Suction valveONOpen
Cut valveONClosed
Inlet valve (FL)OFFOpen
Inlet valve (RR)ONClosed
Outlet valve (FL)OFFClosed
Outlet valve (RR)OFFClosed
Page 332 of 364
DESCRIPTION OF CONSTRUCTION AND OPERATION
ACTIVE STABILITY CONTROL SYSTEM (ASC)35C-22
When the brake fluid pressure is held by the TCL control/stability control (Example:
When the front-left/rear-right whee l system pressure is held)
AC600863AF
MP
Master cylinder
Hydraulic unit
Cut valve
Motor Outlet valve
(RR)Inlet valve (RR)
Wheel cylinder (RR) Suction valve
Pressure sensor
Inlet valve
(FL)
Pump
Outlet valve (FL) Wheel cylinder (FL)
By closing the inlet va lve (FL/RR) and o u tle t valve
(FL/RR), the br
ake f l uid pressure in the wh eel cylin
-
der can be main t a ined.
VA L VE CONDITION
ItemPower statusOpen/Close
Suction valveONOpen
Cut valveONClosed
Inlet valve (FL)ONClosed
Inlet valve (RR)ONClosed
Outlet valve (FL)OFFClosed
Outlet valve (RR)OFFClosed
Page 333 of 364

DESCRIPTION OF CONSTRUCTION AND OPERATION
ACTIVE STABILITY CONTROL SYSTEM (ASC)35C-23
When the brake fluid pressure is reduced by the TCL control/stability control
(Example: When the front-lef t wheel system pressure is reduced/rear-right is held)
AC600863
Master cylinder
AG
Hydraulic unit
Suction valve
Cut valve Pressure sensor
Pump
Motor
MP
Outlet valve
(RR) Outlet valve (FL)
Inlet valve (RR)
Inlet valve
(FL)
Wheel cylinder (RR) Wheel cylinder (FL)
By open ing t he out let valve (FL), the fluid p r essure
applied to
the whee l cylinder (FL ) is returne d to the
master cylinder th
rough t he su ction va lve , reducing
the brake fluid p
r essure in the whe e l cylinder (FL).
The bra
k e fluid p r essure in the whe e l cylinder (RR)
can b
e held by keep ing t he in let valve (RR) and o u t
-
let valve (RR) clos ed.
VA L VE CONDITION
ItemPower statusOpen/Close
Suction valveONOpen
Cut valveONClosed
Inlet valve (FL)ONClosed
Inlet valve (RR)ONClosed
Outlet valve (FL)ONOpen
Outlet valve (RR)OFFClosed
Page 334 of 364
DESCRIPTION OF CONSTRUCTION AND OPERATION
ACTIVE STABILITY CONTROL SYSTEM (ASC)35C-24
Traction control operation
ASC-ECU receives various kinds of information from
the engine ECU, steering wheel sensor, G and yaw
rate sensor, and wheel speed sensor. When
ASC-ECU determines that the driving wheel is slip
-
ping, it suppresses the wheel slippage. At this time,
ASC-ECU controls the brake fluid pressure of the
driving wheel determined to be slipping so that the
torque is transferred to another driving wheel. The operations of suction valve, cut valve, and solenoid
valve are basically the same as that of the stability
control. ASC-ECU and the engine ECU communi
-
cate with each other via CAN bus line. When the
accelerator pedal is depressed too far, the signal
requesting the engine output reduction is sent to the
engine ECU so that the TCL controllability can be
secured.