Mitsubishi Colt Ralliart. Manual - part 635

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-85

TROUBLE SYMPTOM CHART

M1357001000013

CAUTION

During diagnosis, a diagnosis code associated with other system may be set when the ignition switch 
is turned on with connector(s) disconnected. On completion, check if the diagnosis code is set. If the 
diagnosis code has been set, erase that code.

SYMPTOM PROCEDURES

Inspection Procedure 1: Cannot communicate with ASC-ECU using the M.U.T.-III

COMMENTS ON TROUBLE SYMPTOM

If the M.U.T.-III cannot communicate with the 
ASC-ECU, the CAN bus lines may be defective. 
When malfunction occurs in the ASC-ECU power 
supply circuit and earth circuit, the CAN bus diagno-
sis detects the abnormality. This symptom also 
appears when an incorrect vehicle model is selected 
on the M.U.T.-III.

PROBABLE CAUSES

• Damaged wiring harness and connectors

• ASC-ECU malfunction

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III selected vehicle model 
confirmation
Confirm which vehicle model is selected on the 
M.U.T.-III vehicle information screen.

Q: Is the correct vehicle model selected?

YES : 

Go to Step 2.

NO : 

Input the vehicle information correctly.

STEP 2. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES : 

Replace the ASC-ECU.

NO : 

Repair the CAN bus lines. (Refer to GROUP 
54D 

− Troubleshooting 

P.54D-13

.)

Trouble symptom

Inspection 
procedure 
number

Reference page

Cannot communicate with ASC-ECU using the M.U.T.-III

1

P.35C-85

ASC-ECU power supply circuit system

2

P.35C-86

The ABS warning lamp and the ASC indicator lamp don't illuminate when 
the ignition switch is turned ON.

3

P.35C-89

ABS warning lamp and ASC indicator lamp does not extinguish after the 
engine is started.

4

P.35C-90

Brake warning lamp does not illuminate at all.

5

P.35C-91

Brake warning lamp does not illuminate when the parking brake is 
operated. (illuminates when the bulb check is performed.)

6

P.35C-92

Brake warning lamp does not illuminate when the brake fluid level is low 
(illuminates when the parking brake is operated).

7

P.35C-94

Brake warning lamp does not extinguish when the ignition switch is ON 
(remains illuminated).

8

P.35C-96

Stability control system operates too frequently (no diagnosis code is set). 9

P.35C-100

Steering wheel sensor power supply system

10

P.35C-102

G and yaw rate sensor power supply circuit

11

P.35C-105

Main

Index

Group

TOC

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-86

Inspection Procedure 2: ASC-ECU power supply circuit malfunction

OPERATION

• The ASC-ECU is energised by the ignition switch 

(IG1) through multi-purpose fuse 40 and the 
ASC-ECU terminal No. 40.

• When malfunction occurs in ASC-ECU power 

supply, the communication with M.U.T.-III 
becomes unavailable.

PROBABLE CAUSES

• Damaged wiring harness and connectors

• Battery failure

• Charging system failed

• ASC-ECU malfunction

DIAGNOSTIC PROCEDURE

STEP 1. Battery terminal voltage measurement
(1) Ignition switch: ON 
(2) Engine: Started
(3) Measure the voltage between the battery 

terminals.

OK: 10V or more

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Diagnose the charging system. (Refer to 
GROUP 16 

− On-vehicle Service 

P.16-6

.)

ASC-ECU Power Source Circuit

Wire colour code
B : Black     LG : Light green     G : Green     L : Blue     W : White     Y : Yellow     SB : Sky blue
BR : Brown     O : Orange     GR : Grey     R : Red     P : Pink     V : Violet     PU : Purple

IGNITION 
SWITCH (IG1)

ASC-ECU

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Index

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TOC

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-87

STEP 2. Connector check: A-05 ASC-ECU 
connector

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Repair the damaged connector.

STEP 3. Voltage measurement: A-05 ASC-ECU 
connector

(1) Disconnect A-05 ASC-ECU connector, and 

connect the ABS check harness (Special tool: 
MB991984) to the ASC-ECU side connector and 
the harness side connector.

(2) Ignition switch: ON 
(3) Engine: Started
(4) Measure the voltage between the ABS check 

harness (Special tool: MB991984) connector 
terminal No. 40 and the body earth.

OK: 10 V or more

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the harness wire between A-05 
ASC-ECU connector terminal No. 40 and 
the ignition switch (IG1).

AC601083

Connector: A-05

AB

A-05(Black)

Harness side

AC601083

Connector: A-05

AB

A-05(Black)

Harness side

AC601086AD

MB991984

ASC-ECU

Check connector

ASC-ECU harness connector

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TOC

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-88

STEP 4. Measure the resistance at A-05 ASC-ECU 
connector.

(1) Disconnect the A-05 ASC-ECU connector, and 

connect the ABS check harness (Special tool: 
MB991984) to the harness side connector.
NOTE: . Do not connect the ABS check harness 
(Special tool: MB991984) to the ASC-ECU.

(2) Measure the resistance between A-05 ASC-ECU 

connector terminal No. 43 and the body earth.

OK: Continuity exists (2 

Ω or less)

Q: Is the check result normal?

YES : . 

Go to Step 5.

NO : . 

Repair the harness wire between A-05 

ASC-ECU connector terminal No. 43 and 
the body earth.

STEP 5. Retest the system.

Q: Can the ASC-ECU communicate with the M.U.T.-III? 

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Cope with Intermittent 

Malfunction 

P.00-13

.)

NO : 

Replace the ASC-ECU.

AC601083

Connector: A-05

AB

A-05(Black)

Harness side

AC601085AI

MB991984

ASC-ECU

Check connector

ASC-ECU harness connector

Main

Index

Group

TOC