Mitsubishi Lancer Evolution X. Manual - part 135

 

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Mitsubishi Lancer Evolution X. Manual - part 135

 

 

GENERAL INFORMATION

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-5

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.

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 brake warning display 
according to the signal from ASC-ECU.

ASC operation display 
and light

14

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

ASC warning display and 
light

15

The TCL function and skid control 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 display

16

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

SERVICE SPECIFICATIONS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-6

NOTE: 

*

: Only for vehicles with TC-SST

SERVICE SPECIFICATIONS

M1355008200108

DIAGNOSIS

INTRODUCTION TO ASC DIAGNOSIS

M1355000800054

The active stability control system (ASC) operates 
differently from conventional brake systems. These 
differences 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.

Data link connector

17

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

Engine Control Module (ECM)

18

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

TC-SST ECU

*

19

*

Outputs the shift position to ASC-ECU.

AWC ECU

20

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

ASC-ECU

21

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

Item

Standard value

Wheel speed sensor current  mA

5.9 − 8.4 or 11.8 − 16.8

Wheel speed sensor insulation resistance  MΩ

5 or more

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-7

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 Malfunction

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-232

.

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-22

.

• 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

.

PRECAUTIONS FOR DIAGNOSIS

M1355009500113

1. ASC controls the brake pressure by the assistance of ECU. 

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

2. On snowy or gravel roads, a vehicle with ABS sometimes 

requires a 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 place too much confidence on the ABS system when 
driving on such roads.

3. The detection conditions of diagnostic trouble code differ 

with each diagnostic trouble code. When the trouble 
symptoms are rechecked, conditions described in the 
description for the diagnostic trouble code procedures must 
be satisfied.

Symptoms

Description of symptoms

• When ASC operates, the operating noise is generated from 

the motor integrated in the hydraulic unit. (Screech)

• Noise is generated from the brake pedal together with the 

vibration. (Boom, boom)

• When ASC operates, the system repeats the activation and 

deactivation. At this time, the noise is generated from the 
chassis components. (Clunk: Suspension; Squeak: Tire)

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

• A slight shock is felt occasionally when the brake pedal is 

depressed lightly during the low speed driving.

• Small clicking noise is heard occasionally from the engine 

compartment.

This noise is generated when the system 
operation check <startup check 
performed when the vehicle speed is at 
few km/h (mile)> is performed, and it 
does not indicate any malfunction.

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-8

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

M1352012001071

Check that ABS and brake warning light, ASC warning/opera-
tion light illuminate as follows.
NOTE: The brake warning light is used as the warning lights for 
the parking brake, brake fluid level, and EBD control.
1. When the ignition switch is turned to the ON position, ABS 

and brake warning light, ASC warning/operation light 
illuminate.

2. The ABS and brake warning light, ASC warning/operation 

light illuminate for three seconds

*1

 and then turn OFF

*2

.

3. Other than the above, the system may have a malfunction. 

Check the diagnostic trouble code.

NOTE: 

.

*1

: The ABS warning light may stay ON until the vehicle 

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

*2

: The brake warning light does not turn OFF when the 

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

DIAGNOSTIC FUNCTION

M1355001000545

ASC-ECU has the following functions for easier sys-
tem checks. All the following items can be diagnosed 
using the scan tool.

• Diagnostic trouble code set (Refer to 

P.35C-22

.)

• Service data output (Refer to 

P.35C-276

.)

• Actuator test (Refer to 

P.35C-278

.)

• Freeze frame data output (Refer to 

P.35C-8

).

All the above items can be diagnosed using scan 
tool.

CHECK OF FREEZE FRAME DATA

The freeze frame data can be checked by using the 
scan tool.

.

When detecting fault and storing the DTC, the ECU 
connected to CAN bus line obtains the data before 
the determination of the DTC and the data when the 
DTC is determined, and then stores the ECU status 
of that time. By analyzing each data from scan tool, 
the troubleshooting can be performed more effi-
ciently. The displayed items are as the table below.

AC901746AC

ABS warning light

ABS warning
light, Brake
warning light,
ASC warning/
operation light

Ignition switch

Illuminated

Approximately 3s

ON
ACC,
LOCK

START

Not
illuminated

ASC warning/
operation light

Brake warning light
<Vehicles for CANADA>

Brake warning light
<Vehicles for USA>

 

 

 

 

 

 

 

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