Mitsubishi Lancer (4A9 engine). Manual — part 70

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-133

YES :

Troubleshoot for the relevant diagnosis

code, and then go to Step 5.

NO :

Go to Step 5.

STEP 5. Check whether the diagnosis code is
reset.
Erase the diagnosis code.

Q: Is Code No. U1004 set?

YES :

Replace the hydraulic unit (integrated with

ASC-ECU) (Refer to

P.35C-185

.), and then

go to Step 6.

NO :

Intermittent malfunction (Refer to GROUP
00

− How to Cope with Intermittent

Malfunctions .).

STEP 6. Check whether the diagnosis code is
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.U1004 set?

YES :

Return to Step 1.

NO :

This diagnosis is complete.

Code No. U0125 G and yaw rate sensor message time-out error/message error

G and Yaw Rate Sensor Circuit

G AND YAW RATE SENSOR

ASC-ECU

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 SI : Silver

ACB02567

AC612691

Connector: A-58 <LHD>

A-58 (B)

AC701238 AF

Connector: A-58 <RHD>

A-58 (B)

AC612705

Connector: C-137 <LHD>

C-137 (B)

AC701122

Connector: C-137 <RHD>

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-134

CAUTION

• If there is any problem in the CAN bus lines,

an incorrect diagnosis code may be set. Prior
to this diagnosis, diagnose the CAN bus lines
(Refer to GROUP 54C

− CAN Bus Diagnostics

Table ).

• Whenever ECU is replaced, ensure that the

CAN bus lines are normal.

• Do not drop or shock the G and yaw rate sen-

sor.

• When the G and yaw rate sensor is replaced,

always carry out calibration to make ASC-
ECU learn the neutral point (Refer to

P.35C-

182

• When the hydraulic unit (integrated with ASC-

ECU) is replaced, always carry out the calibra-
tion of the steering wheel sensor, the G and
yaw rate sensor and brake fluid pressure sen-
sor (Refer to

and

OPERATION
The G and yaw rate sensor outputs the signal to
ASC-ECU via the special CAN bus lines.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when the ASC-ECU can-
not receive the signal from the G and yaw rate sen-
sor although there is no abnormality in ASC-ECU
supply voltage.

PROBABLE CAUSES

• Wiring harness or connector failure for the spe-

cial CAN bus lines between ASC-ECU and the G
and yaw rate sensor

• G and yaw rate sensor malfunction

• ASC-ECU malfunction

• External noise interference

• Connector disconnected or improperly connected

• Stretched or broken wires

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES :

Go to Step 3.

NO :

Repair the CAN bus lines (Refer to GROUP
54C

− CAN Bus Diagnostics Table ). On

completion, go to Step 2.

STEP 2. Diagnosis code recheck after resetting
CAN bus lines

Q: Is diagnosis code No. U0125 set?

YES :

Go to Step 3.

NO :

This diagnosis is complete.

STEP 3. Connector check: A-58 ASC-ECU
connector, C-137 G and yaw rate sensor
connector

Q: Is the check result normal?

YES :

Go to Step 4.

NO :

Repair the connector, and then go to Step 7.

STEP 4. Wiring harness check between A-58
ASC-ECU connector terminal No. 18 and C-137 G
and yaw rate sensor connector terminal No. 3 as
well as between A-58 ASC-ECU connector
terminal No. 19 and C-137 G and yaw rate sensor
connector terminal No. 2

• Check the communication circuit for open and

short circuit.

Q: Is the check result normal?

YES :

Go to Step 5.

NO :

Repair the wiring harness, and then go to
Step 7.

STEP 5. Diagnosis code recheck
Erase the diagnosis code.

Q: Is diagnosis code No. U0125 set?

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-135

YES :

Replace the G and yaw rate sensor (Refer

P.35C-189

). Then go to Step 6.

NO :

Intermittent malfunction (Refer to GROUP
00

− How to Use Troubleshooting/How to

Cope with Intermittent Malfunctions ).

STEP 6. Diagnosis code recheck
Erase the diagnosis code.

Q: Is diagnosis code No. U0125 set?

YES :

Replace the hydraulic unit (integrated with

ASC-ECU). (Refer to

P.35C-185

). Then go

to Step 7.

NO :

This diagnosis is complete.

STEP 7. Diagnosis code recheck
Erase the diagnosis code.

Q: Is diagnosis code No. U0125 set?

YES :

Return to Step 1.

NO :

This diagnosis is complete.

Code No. U0401 Engine signal malfunction detected

CAUTION

• If there is any problem in the CAN bus lines,

an incorrect diagnosis code may be set. Prior
to this diagnosis, diagnose the CAN bus lines
(Refer to GROUP 54C

− CAN Bus Diagnostics

Table ).

• If diagnosis code No.U0401 is set in ASC-

ECU, always diagnose the CAN bus line. If
there is any fault in the CAN bus lines, an
incorrect diagnosis code may be set. In this
case, the set diagnosis code is not highly reli-
able.

• Before replacing the ECU, ensure that the

communication circuit is normal.

OPERATION
Engine-related signals are sent or received to and
from between ASC-ECU and engine ECU via CAN
bus lines.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when the engine ECU
malfunction has been detected.

PROBABLE CAUSES

• Malfunction of engine system

• Malfunction of engine ECU

• Malfunction of ASC-ECU

• External noise interference

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnosis
Use M.U.T.-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES :

Go to Step 2.

NO :

Repair the CAN bus lines (Refer to GROUP
54C

− CAN Bus Diagnostics Table ). On

completion, go to Step 5.

STEP 2. M.U.T.-III diagnosis code
Use M.U.T.-III to check that any diagnosis code other
than the code No.U0401 is set in ASC-ECU.

Q: Is the diagnosis code set?

YES :

Troubleshoot the relevant diagnosis code,

and then go to Step 5.

NO :

Go to Step 3.

STEP 3. M.U.T.-III other system diagnosis code
Use M.U.T.-III to check that the diagnosis code is set
by the engine ECU.

Q: Is the diagnosis code set?

YES :

Troubleshoot the relevant diagnosis code,

and then go to Step 5.

NO :

Go to Step 4.

STEP 4. Check whether the diagnosis code is
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.U0401 set?

YES :

Replace the hydraulic unit (integrated with

ASC-ECU) (Refer to

P.35C-185

), and then

go to Step 5.

NO :

Intermittent malfunction (Refer to GROUP
00

− How to Use Troubleshooting/How to

Cope with Intermittent Malfunctions ).

STEP 5. Check whether the diagnosis code is
reset.
Erase the diagnosis code.

Q: Is diagnosis code No.U0401 set?

YES :

Return to Step 1.

NO :

This diagnosis is complete.

TROUBLESHOOTING

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-136

Code No. U0428 Communication error in steering wheel sensor

CAUTION

• If there is any problem in the CAN bus lines,

an incorrect diagnosis code may be set. Prior
to this diagnosis, diagnose the CAN bus lines
(Refer to GROUP 54C

− CAN Bus Diagnostics

Table ).

• If diagnosis code U0428 is set in ASC-ECU,

always diagnose the CAN bus line. If there is
any fault in the CAN bus lines, an incorrect
diagnosis code may be set. In this case, the
set diagnosis code is not highly reliable.

• Before replacing the ECU, ensure that the

communication circuit is normal.

• When the hydraulic unit (integrated with ASC-

ECU) is replaced, always carry out the calibra-
tion of the steering wheel sensor, the G and
yaw rate sensor and brake fluid pressure sen-
sor (Refer to

and

OPERATION
The steering wheel sensor outputs the steering
wheel status to ASC-ECU via the CAN bus lines.

DIAGNOSIS CODE SET CONDITIONS
This diagnosis code is set when ASC-ECU has
detected the communication error in the steering
wheel sensor.

PROBABLE CAUSES

• Steering wheel sensor malfunction

• ASC-ECU malfunction

• External noise interference

DIAGNOSIS PROCEDURE