Mitsubishi Evolution X. Manual - part 158

DESCRIPTION OF CONSTRUCTION AND OPERATION

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-17

When brake fluid pressure is increased by skid control (or increased by TCL)

The system closes the cut valve to block the pas-
sage from the pump outlet to the master cylinder, 
and opens the suction valve, connecting the passage 
from the master cylinder to the pump inlet. The brake 
fluid drawn from the master cylinder is supplied to 
the wheel cylinder.

VALVE CONDITION

NOTE: 

*

: Because the brake fluid pressure for each 

wheel is controlled depending on the driving status, 
the open/close status of inlet valve and outlet valve 
changes according to the driving status.

.

AC703859AE

Hydraulic unit

Outlet valve

Inlet valve

Wheel 
cylinder 
(front)

Wheel 
cylinder 
(rear)

Wheel cylinder 
brake fluid
pressure 
sensor

Low pressure 
accumulator

Brake fluid flow

Pump

Damping 
chamber

Motor

Suction valve

Cut valve

Master cylinder

Wheel cylinder 
brake fluid
pressure sensor

Outlet valve

Inlet valve

Master cylinder 
brake fluid 
pressure sensor

Suction 
damper

Item

Power status

Open/Close

Cut valve

ON

Closed

Suction valve

ON

Open

Inlet valve

*

OFF

Open

Outlet valve

*

OFF

Closed

DESCRIPTION OF CONSTRUCTION AND OPERATION

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-18

When brake fluid pressure is held by skid control (or held by TCL)

In order to hold the brake fluid pressure in the wheel 
cylinder, the system closes the cut valve, suction 
valve, and outlet valve.

Valve status

NOTE: 

*

: In order to control the brake fluid pressure 

supplied to each wheel based on the vehicle driving 
status, the inlet valve and outlet valve are 
opened/closed.

.

AC703859AF

Hydraulic unit

Outlet valve

Inlet valve

Wheel 
cylinder 
(front)

Wheel 
cylinder 
(rear)

Wheel cylinder 
brake fluid
pressure 
sensor

Low pressure 
accumulator

Brake fluid flow

Pump

Damping 
chamber

Motor

Suction valve

Cut valve

Master cylinder

Wheel cylinder 
brake fluid
pressure sensor

Outlet valve

Inlet valve

Master cylinder 
brake fluid 
pressure sensor

Suction 
damper

Item

Power status

Open/Close

Cut valve

ON

Closed

Suction valve

OFF

Closed

Inlet valve

*

OFF

Open

Outlet valve

*

OFF

Closed

DESCRIPTION OF CONSTRUCTION AND OPERATION

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-19

When brake fluid pressure is decreased by skid control (or decreased by TCL)

The system opens the outlet valve while closing the 
inlet valve to store the brake fluid filled in the wheel 
cylinder in the low pressure accumulator. The brake 
fluid stored in the low pressure accumulator returns 
to the master cylinder for circulation when the pump 
is driven by the motor.

VALVE CONDITION

NOTE: 

*

: In order to control the brake fluid pressure 

supplied to each wheel based on the vehicle driving 
status, the inlet valve and outlet valve are 
opened/closed.

AC703859

Master cylinder

Hydraulic unit

Wheel 
cylinder 
(front)

Wheel 
cylinder 
(rear)

Inlet valve

Damping 
chamber

Pump

Motor

Brake fluid flow

Suction valve

Cut valve

Wheel cylinder 
brake fluid
pressure 
sensor

AB

Suction 
damper

Low pressure 
accumulator

Outlet valve

Master cylinder 
brake fluid 
pressure sensor

Outlet valve

Inlet valve

Wheel cylinder 
brake fluid
pressure 
sensor

Item

Power status

Open/Close

Cut valve

OFF

Open

Suction valve

OFF

Closed

Inlet valve

*

ON

Closed

Outlet valve

*

ON

Open

DESCRIPTION OF CONSTRUCTION AND OPERATION

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ACTIVE SKID CONTROL SYSTEM (ASC)

35C-20

TCL OPERATION

ASC-ECU receives various kinds of information from 
the engine control module, TC-SST-ECU, 
S-AWC-ECU, steering wheel sensor, G and yaw rate 
sensor, and wheel speed sensor. When ASC-ECU 
determines that the driving wheel is slipping, it sup-
presses 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 trans-
ferred to another driving wheel. Basically, the opera-
tions of ABS solenoid valve and ASC valve are the 
same as with the skid control. ASC-ECU, engine 
control module, TC-SST-ECU, and S-AWC-ECU 
communicate with each other via the CAN bus lines. 
When the accelerator pedal is depressed too far, a 
signal requesting to reduce the engine output is sent 
to the engine control module. Also, a joint control 
with TC-SST-ECU and S-AWC-ECU are performed 
to secure the TCL controllability.