Mitsubishi Colt Ralliart. Manual — part 638

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-97

COMMENTS ON TROUBLE SYMPTOM

• The brake warning lamp drive signal at the EBD

system error and the low brake fluid level is sent
from the ASC-ECU to the combination meter
through the CAN communication lines.

• If the combination meter detects a ASC time-out

due to a failure in the power supply to the
ASC-ECU or abnormal CAN communication, the
combination meter illuminates the lamp.

• The ASC-ECU sends the lamp drive signal to the

combination meter during a bulb check (for three
seconds after the ignition switch is turned on)
through the CAN communication lines, and then
the combination meter activates the lamp.

• If the combination meter detects a ASC time-out

due to a failure in abnormal CAN communication,
the combination meter illuminates the lamp.

• This symptom appears when the brake fluid level

switch or the parking brake switch is shorted to
earth. When the brake fluid level witch is shorted
to earth, the diagnosis code No. C1345 is set.

PROBABLE CAUSES

• Damaged wiring harness and connectors

• Parking brake switch malfunction

• Brake fluid level switch malfunction

• Combination meter assembly malfunction

• ASC-ECU malfunction

DIAGNOSTIC PROCEDURE

STEP 1. Check the brake fluid level.
Check that the brake fluid is filled to the specified.

Q: Is the check result normal?

YES :

Check the brake pad remaining thickness,

fill the brake fluid to the specified, and then
go to Step 12.

NO :

Go to Step 2.

STEP 2. M.U.T.-III data list
Using the data list, check that the parking brake input
signal and the brake fluid level switch signal are nor-
mal.(Refer to

P.35C-109

.)

• Item No. 28: Side brake switch

• Item No. 32: Brake fluid level switch

Q: Is the check result normal?

YES :

Go to Step 10.

NO :

Go to Step 3.

STEP 3. Check the brake fluid level switch as a
single unit.
Refer to GROUP 35A

− On-vehicle Service

P.35A-11

.

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Replace the reservoir assembly. (Refer to
GROUP 35A

− Master cylinder assembly

and brake booster

P.35A-23

.)

STEP 4. Check A-03 brake fluid level switch
connector and A-05 ASC-ECU connector.

Q: Is the check result normal?

YES :

Go to Step 5.

NO :

Repair the A-03 brake fluid level switch
connector and the A-05 ASC-ECU
connector.

AC601084

Connector: A-03

AD

A-03(Grey)

Harness
side

AC601083

Connector: A-05

AB

A-05(Black)

Harness side

Main

Index

Group

TOC

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-98

STEP 5. Measure the resistance at A-03 brake
fluid level switch connector and A-05 ASC-ECU
connector.

(1) Disconnect A-03 brake fluid level switch

connector and A-05 ASC-ECU connector.

(2) Make the brake fluid below the specified level,

and turn ON the brake fluid level switch.

(3) Measure the resistance between A-03 brake fluid

level switch connector terminal No. 2 and A-05
ASC-ECU connector terminal No. 32.

OK: Continuity exists (2

Ω or less)

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Repair the harness wire between A-03
brake fluid level switch connector terminal
No. 2 and A-05 ASC-ECU connector
terminal No. 32.

STEP 6. Measure the resistance at A-03 brake
fluid level switch connector.

(1) Disconnect A-03 brake fluid level switch

connector.

(2) Measure the resistance between A-03 brake fluid

level switch connector terminal No. 2 and the
body earth.

OK: Continuity exists (2

Ω or less)

Q: Is the check result normal?

YES :

Go to Step 7.

NO :

Repair the harness wire between A-03
brake fluid level switch connector terminal
No. 2 and body earth.

STEP 7. Check the parking brake switch as single
unit.
Refer to GROUP 36

− On-vehicle Service

P.36-5

.

Q: Is the check result normal?

YES :

Go to Step 8.

NO :

Replace the parking brake switch. (Refer to
GROUP 36

− Parking brake lever

P.36-7

.)

AC601110

Connector: A-03, A-05

A-05
(Black)

A-03(Grey)

AB

A-03: Harness side

A-05: Harness side

AC601084

Connector: A-03

AE

A-03(Grey)

Harness side

Main

Index

Group

TOC

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-99

STEP 8. Check A-05 ASC-ECU connector and
C-42 parking brake switch connector.

Q: Is the check result normal?

YES :

Go to Step 9.

NO :

Repair.

STEP 9. Measure the resistance at A-05 ASC-ECU
connector.

(1) Disconnect the A-05 ASC-ECU connector.
(2) Pull the parking brake lever and turn the parking

brake switch to ON.

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

connector terminal No. 27 and the body earth.

OK: Continuity exists (2

Ω or less)

Q: Is the check result normal?

YES :

Go to Step 12.

NO :

Repair the harness wire between A-05
ASC-ECU connector terminal No. 27 and
C-42 parking brake switch connector
terminal No. 1.

AC601083

Connector: A-05

AB

A-05(Black)

Harness side

AC601093

Connector: C-44

AD

C-44(Black)

Harness side

AC601083

Connector: A-05

AB

A-05(Black)

Harness side

AC601085

AC601085AJ

MB991984

ASC-ECU

Check connector

ASC-ECU harness connector

Main

Index

Group

TOC

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-100

STEP 10. Retest the system.

Q: Does the brake warning lamp go off when the

ignition switch is ON?
YES :

Intermittent malfunction (Refer to GROUP

00

− How to Cope with Intermittent

Malfunction

P.00-13

.)

NO :

Replace the combination meter assembly,
and then go to Step 11.

STEP 11. Retest the system.

Q: Does the brake warning lamp go off when the

ignition switch is ON?
YES :

This diagnosis is complete.

NO :

Replace the ASC-ECU.

STEP 12. Retest the system.

Q: Does the brake warning lamp go off when the

ignition switch is ON?
YES :

Intermittent malfunction (Refer to GROUP

00

− How to Cope with Intermittent

Malfunction

P.00-13

.)

NO :

Replace the ASC-ECU.

Inspection Procedure 9: The stability control system operates too frequently. (the diagnosis code is
not set.)

COMMENTS ON TROUBLE SYMPTOM

• This symptom does not appear due to a failure in

wiring harness (open or short circuit, or excessive
resistance). Therefore, if the sensors are installed
properly and the check result does not indicate
any problems, replace the ASC-ECU.

• This symptom does not appear at steering wheel

sensor calibration. (The diagnosis code is set.)

NOTE: If the steering neutral position fluctuates

slightly, the ASC system may activate early.

PROBABLE CAUSES

• Wheel speed sensor malfunction

• G and yaw rate sensor malfunction

• Steering wheel sensor malfunction

• Wheel bearing malfunction

• ASC-ECU malfunction

• Malfunction of magnetic encoder for wheel speed

detection

DIAGNOSTIC PROCEDURE

STEP 1. G and yaw rate sensor installation check
Check that the G and yaw rate sensor is installed
correctly.

Q: Is the check result normal?

YES :

Go to Step 2.

NO :

Reinstall the G and yaw rate sensor
correctly.

STEP 2. M.U.T.-III data list
Using the data list, check the G and yaw rate sensor
output value.(Refer to

P.35C-109

.)

• Item No. 14: Lateral G-sensor

• Item No.17: Yaw rate sensor

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Replace the G and yaw rate sensor.

STEP 3. Steering wheel sensor installation state
check
Check that the steering wheel sensor is installed cor-
rectly.

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Install the steering wheel sensor correctly.

STEP 4. M.U.T.-III data list
Using the data list, check the steering sensor output
value.(Refer to

P.35C-109

.)

• Item No. 16: Steering angle sensor

Q: Is the check result normal?

YES :

Go to Step 5.

NO :

Replace the steering wheel sensor.

STEP 5. Check how wheel speed sensor is
installed.
Check that the wheel speed sensor is installed cor-
rectly.

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Reinstall the wheel speed sensor correctly.

Main

Index

Group

TOC