Mitsubishi Evolution X. Manual — part 749

GENERAL INFORMATION

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-3

CONSTRUCTION DIAGRAM

.

AC708742

CHECK

SERVICE
REQUIRED

SERVICE
REQUIRED

10

12

13

11

15

14

17

5

3

19

AB

1

1

2

2

4

20

16

7, 8, 9, 22

6

18

21

GENERAL INFORMATION

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-4

MAIN COMPONENTS AND FUNCTIONS

Parts name

No. Functional description

Sensor

Wheel speed sensor

1

Outputs the frequency pulse signal in proportion to the
rotation speed of each wheel to ASC-ECU.

Magnetic encoder for
wheel speed detection

2

When the magnetic encoder for wheel speed detection
(a plate on which north and south pole sides of the
magnets are arranged alternately) rotates, the wheel
speed sensor outputs frequency pulse signal in
proportion to each wheel speed.

Stoplight switch

3

Outputs the signal indicating whether the brake pedal
is depressed or not to ASC-ECU.

G and yaw rate sensor

4

Detects the yaw rate, and longitudinal and lateral
acceleration of a vehicle, then outputs the signal to
ASC-ECU via the CAN line.

Steering wheel sensor

5

Detects the steering angle of steering wheel, and
outputs the signal to ASC-ECU via the CAN bus line.

ASC OFF switch

6

Outputs the ASC ON/OFF signal to ASC-ECU.

Master cylinder pressure
sensor

7

Integrated into the hydraulic unit, converts the signal of
brake fluid pressure in master cylinder to the voltage
value, then outputs the value to ASC-ECU.

Wheel cylinder pressure
sensor

8

Integrated into the hydraulic unit, converts the signal of
brake fluid pressure in wheel cylinder of each wheel to
the voltage value, then outputs the value to ASC-ECU.

GENERAL INFORMATION

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-5

NOTE:

.

•

*1

: For information on AYC (Active Yaw Control),

refer to technical information manual.

•

*2

: Only for vehicles with TC-SST

Actuator

Hydraulic unit

9

Drives the solenoid valve using the signal from
ASC-ECU, and controls the brake fluid pressure for
each wheel.

ABS warning light

10

Informs the driver of the system status by illuminating,
flashing, or turning off the warning light according to
the signal from ASC-ECU.

ABS warning display

11

Informs the driver of the system status by illuminating
or turning off the warning light according to the signal
from ASC-ECU.

Brake warning light

12

Used as the warning light for the parking brake, brake
fluid level, and EBD control. Informs the driver of the
system status by illuminating or turning off the warning
light according to the signal from ASC-ECU.

Brake warning display

13

Used as the warning light for the brake fluid level and
EBD control. Informs the driver of the system status by
illuminating or turning off the warning light according to
the signal from ASC-ECU.

ASC operation display

14

According to the signal from ASC-ECU, flashes when
the system is active to inform the driver of the status.

ASC warning display

15

The TCL function and ASC function use the same
display. According to the signal from ASC-ECU, the
display is illuminated to inform the driver that the
system is abnormal.

ASC OFF light

16

Informs the driver of the ASC system shutdown by
illuminating according to the signal from ASC-ECU.

ASC OFF display

17

Using the signal from ASC-ECU, the display is
illuminated to inform the driver that the ASC OFF
switch is pressed and held for 3 seconds, and that the
ASC and AYC

*1

brake control is prohibited.

Data link connector

18

Outputs the diagnostic trouble code and establishes
the communication with the scan tool.

Engine ECU

19

Controls the engine output based on the signal from
ASC-ECU.

TC-SST ECU

*2

20

*2

Outputs the shift position to ASC-ECU.

S-AWC ECU

21

Outputs the drive status and brake fluid pressure
request to ASC-ECU.

ASC-ECU

22

Controls the actuators (described above) based on the
signals coming from each sensors.
Controls the self-diagnostic functions and fail-safe
functions.
Controls diagnostic function (Compatible with scan
tool).

Parts name

No. Functional description

SERVICE SPECIFICATIONS

TSB Revision

ACTIVE SKID CONTROL SYSTEM (ASC)

35C-6

SERVICE SPECIFICATIONS

M1355008200108

DIAGNOSIS

INTRODUCTION TO ASC DIAGNOSIS

M1355000800054

The active skid control system (ASC) operates differ-
ently from conventional brake systems. These differ-
ences include sounds, sensations, and vehicle
performance that owners and service technicians
who are not familiar with ASC may not be used to.

Some operational characteristics may seem to be
malfunctions, but they are simply signs of normal
ASC operation. When diagnosing the ASC system,
keep these operational characteristics in mind.
Inform the owner of the kind of performance charac-
teristics to expect from an ASC-equipped vehicle.

ASC DIAGNOSTIC TROUBLE CODE
DETECTION CONDITIONS

ASC diagnostic trouble codes (ASC DTCs) are set
under different conditions, depending on the mal-
function detected. Most ASC DTCs will only be set
during vehicle operation. Some ASC DTCs will also
be set during the ASC self-check immediately after
the engine is started.

When you check if an ASC DTC will be displayed
again after the DTC has been erased, you should
duplicate the ASC DTC set conditions. Depending on
the detection timing and set conditions for the spe-
cific ASC DTC, you must either drive the vehicle or
turn the engine off and restart it. To set the proper
conditions for that DTC again, refer to "ASC DTC
SET CONDITIONS" for each ASC DTC that you are
trying to reset.

ASC DIAGNOSTIC TROUBLESHOOTING STRATEGY

M1355000900147

Use these steps to plan your diagnostic strategy. If
you follow them carefully, you will be sure that you
have exhausted most of the possible ways to find an
ASC fault.
1. Gather information about the problem from the

customer.

2. Verify that the condition described by the

customer exists.

3. Check the vehicle for any ASC DTC.
4. If you cannot verify the condition and there are no

ASC DTCs, the malfunction is intermittent. Refer
to GROUP 00, How to use
Troubleshooting/Inspection Service Points

− How

to Cope with Intermittent Malfunctions

P.00-15

.

5. If you can verify the condition but there are no

ASC DTCs, or the system cannot communicate
with the scan tool, check that the basic brake
system is operating properly.

• If the basic brake system is not operating prop-

erly, refer to the GROUP 35A, Basic Brake Sys-
tem Diagnostic troubleshooting strategy

P.35A-4

.

• If the basic brake system is operating properly,

refer to

P.35C-219

.

6. If there is an ASC DTC, record the number of the

DTC, then erase the DTC from the memory using
the scan tool.

7. Recreate the ASC DTC set conditions to see if the

same ASC DTC will set again.

• If the same ASC DTC sets again, perform the

diagnostic procedures for the DTC. Refer to

P.35C-20

.

• If you cannot get the same ASC DTC to set

again, the malfunction is intermittent. Refer to
GROUP 00, How to use Troubleshooting/Inspec-
tion Service Points

− How to Cope with Intermit-

tent Malfunctions

P.00-15

.

Item

Standard value

Wheel speed sensor current mA

5.9

− 8.4 or 11.8 − 16.8

Wheel speed sensor insulation resistance M

Ω

5 or more