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Mitsubishi Lancer (4A9 engine). Manual - part 38

SPECIAL TOOL

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-5

SPECIAL TOOL

M1355005800349

Tool

Number

Name

Use

MB991910

MB991826

MB991955

MB991911

MB991824

MB991827

MB991825

DO NOT USE

MB991955

a. MB991824
b. MB991827
c. MB991910
d. MB991911
e. MB991825
f. MB991826

M.U.T.-III sub-assembly

a. Vehicle

Communication
Interface (V.C.I.)

b. M.U.T.-III USB cable
c. M.U.T.-III main

harness A (Vehicles
with CAN
communication
system)

d. M.U.T.-III main

harness B (Vehicles
without CAN
communication
system)

e. M.U.T.-III

measurement adapter

f. M.U.T.-III trigger

harness

CAUTION

For vehicles with CAN
communication, use
M.U.T.-III main harness
A to send the simulated
vehicle speed. If you
connect M.U.T.-III main
harness B instead, CAN
communication does
not function correctly.
ASC check (Diagnosis
code display, data list
display and calibration by
M.U.T.-III)

MB991997

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-6

TROUBLESHOOTING

DIAGNOSIS TROUBLESHOOTING FLOW

M1355000900114

Refer to GROUP 00

− How to Use Troubleshooting/

Inspection Service Points .

PRECAUTIONS FOR DIAGNOSIS

M1355009500168

1. ASC controls brake pressure by the assistance of

ECU. The symptoms described in the chart below
may occur during the normal ASC operation, and
they do not indicate any sign of malfunction.

Symptoms

Description of symptoms

• When the ASC operates, the operating noise is generated

from the motor. (Squeak noise)

• Noise is generated from the brake pedal together with the

vibration. (Gride noise)

• When ABS operates, the system repeats the activation and

deactivation. At this time, the noise is generated from the
chassis components. (Clonk: Suspension, Squeaky: Tyres)

These noises are generated when the
system and brake pedal operate
normally, and they do not indicate any
sign of malfunction.

• A slight shock may be felt when depressing the brake pedal

lightly during the low speed driving.

• Small clicking noise may be heard from the engine

compartment.

This noise is generated when the system
operation check (startup check
performed at the vehicle speed which is a
few km/h higher than the predetermined
vehicle speed) is performed, and it does
not indicate malfunction.

2. On the snowy or gravelled roads, a vehicle with

ABS would have longer braking distance
compared to the one without ABS. Considering
this characteristics, advise the customer to drive
the vehicle safely at lower speed and not to put
too much confidence in the ABS system when
driving on the above-mentioned roads.

3. The diagnosis code detection condition depends

on each diagnosis code. When the trouble
symptoms are rechecked, conditions described in
the description for the diagnosis code procedures
should be met.

MB991997

ASC check harness

Voltage inspection at
ASC-ECU terminals

MB992006

MB992006

Extra fine probe

Continuity check and
voltage measurement at
wiring harness or
connector

MB991709

Wiring harness set

Output current measure
at the wheel speed
sensor

Tool

Number

Name

Use

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-7

ABS WARNING LAMP, ASC WARNING/
OPERATION LAMP AND BRAKE
WARNING LAMP CHECK

M1352012001208

Check that ABS and brake warning lamps, ASC
warning/operation lamp illuminate as follows.
NOTE: The brake warning lamp is used as a warning
lamp for parking brake, brake fluid level, and EBD
control.

AC700575AH

ABS warning lamp

ABS warning
lamp, Brake
warning lamp,
ASC warning/
operation lamp

Ignition switch

Illuminated

Approximately 3s

ON
ACC,
LOCK

START

Brake warning lamp

Not
illuminated

ASC warning/
operation lamp

1. When the ignition switch is turned to the ON

position, ABS and brake warning lamps, ASC
warning/operation lamp illuminate.

2. The ABS and brake warning lamps, ASC warning/

operation lamp illuminate for three seconds

and

then turn OFF

3. Otherwise, check the diagnosis code.
NOTE:

•

: The ABS warning lamp may stay ON until the

vehicle speed reaches 10 km/h. As far as ABS-
ECU stores any diagnosis code related to the
wheel speed sensor malfunction or the motor
malfunction as past trouble, ABS-ECU continues
illuminating the ABS warning lamp until it verifies
that the malfunction for that code is resolved
(startup check).

•

: The brake warning lamp does not turn OFF

when the parking brake is applied or the brake
fluid level is lowered.

DIAGNOSTIC FUNCTION

M1355001000846

ASC-ECU has the following functions for easier sys-
tem checks.

• Diagnosis code set (Refer to

P.35C-16

• Service data output (Refer to

P.35C-172

• Actuator test (Refer to

P.35C-175

• Freeze frame data output (Refer to ).

All the above items can be diagnosed using M.U.T.-
III.

CHECK OF FREEZE FRAME DATA

The freeze frame data can be checked by using the
M.U.T.-III.

When detecting fault and storing the diagnosis code,
the ECU connected to CAN bus line obtains the data
before the determination of the diagnosis code and
the data when the diagnosis code is determined, and
then stores the ECU status of that time. By analysing
each data from M.U.T.-III, the troubleshooting can be
performed more efficiently. The displayed items are
as the table below.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-8

Display item list

Item No.

Item name

Data item

Unit

Odometer

Total driving distance after the diagnosis code is
generated

Ignition cycle

Number of times the ignition switch is turned "ON" or
"LOCK (OFF)" after the past failure transition

Number of
counts is
displayed.

Accumulated minute Cumulative time for current malfunction of diagnosis

code

min

Power supply
voltage

Voltage of power supply when the diagnosis code is
generated

Lateral G sensor

Lateral G of G and yaw rate sensor when the
diagnosis code is generated

G sensor

Longitudinal G of G and yaw rate sensor when the
diagnosis code is generated

Master cylinder
pressure

Master cylinder pressure of Master cylinder pressure
sensor when the diagnosis code is generated

bar

Steering angle

Steering angle of steering wheel sensor when the
diagnosis code is generated

bar

Yaw rate sensor

Yaw rate of G and yaw rate sensor when the
diagnosis code is generated

Stop lamp switch

Stop lamp switch condition when the diagnosis code
is generated: OFF/ON

−

Pump motor

Pump motor condition when the diagnosis code is
generated: OFF/ON

−

ASC/TCL off switch

ASC OFF switch condition when the diagnosis code
is generated: OFF/ON

−

301

ABS control

ABS control when the diagnosis code is generated:
OFF/ON

−

302

Brake TCL control

Traction control (brake control) when the diagnosis
code is generated: OFF/ON

−

303

Engine TCL control

Traction control (engine control) when the diagnosis
code is generated: OFF/ON

−

304

ASC control

ASC control when the diagnosis code is generated:
OFF/ON

−

305

Brake TCL operation Traction control (brake control) operation when the

diagnosis code is generated: Permission/Prohibition

−

401

FL wheel speed
sensor

Wheel speed (FL) when the diagnosis code is
generated

km/h

402

FR wheel speed
sensor

Wheel speed (FR) when the diagnosis code is
generated

km/h

403

RL wheel speed
sensor

Wheel speed (RL) when the diagnosis code is
generated

km/h

404

RR wheel speed
sensor

Wheel speed (RR) when the diagnosis code is
generated

km/h

Content .. 36 37 38 39 ..