Mitsubishi Lancer Evolution X. Manual — part 187

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-213

CAUTION

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

rect diagnostic trouble code may be set. Prior to this
diagnosis, diagnose the CAN bus lines.

• Whenever the ECU is replaced, ensure that the CAN

bus lines are normal.

• Do not drop the G and yaw rate sensor or subject it to a

shock.

• When the G and yaw rate sensor is replaced, always

perform the calibration to make ASC-ECU learn the
neutral point. (Refer to

P.35C-287

• When the hydraulic unit (integrated with ASC-ECU) is

replaced, after turning the ignition switch ON and OFF
(vehicle information from ETACS-ECU is registered),
always perform the calibration of steering wheel sen-
sor, G and yaw rate sensor, brake fluid pressure sen-
sor, cut valve, and inlet valve.(Refer to

, and

CIRCUIT OPERATION

The G and yaw rate sensor outputs the signal to ASC-ECU and
AWC-ECU via the special CAN bus lines (Local CAN).

DTC SET CONDITIONS

This diagnostic trouble code is set if ASC-ECU cannot receive
the signal sent from the G and yaw rate sensor even when the
voltage supplied to ASC-ECU is normal.

PROBABLE CAUSES

• Wiring harness or connector failure in special CAN bus lines

(Local CAN) between ASC-ECU and G and yaw rate sen-
sor.

• G and yaw rate sensor malfunction
• ASC-ECU malfunction
• External noise interference

AC708950AN

C-46

C-50 (B)

Connectors: C-46, C-47, C-50

C-47

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-214

DIAGNOSIS

Required Special Tools:

• MB991958 Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)
• MB991827 M.U.T.-III USB Cable
• MB991910 M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus
lines.
Using scan tool MB991958, 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 −

Troubleshooting

P.54C-15

.) After repairing the CAN

bus line, go to Step 3.

STEP 2. Check for diagnostic trouble codes
Check if diagnostic trouble code No. U0251, U0440, and
U0435 are simultaneously set in ASC-ECU.
Q: Are DTCs U0251, U0440 or U0435 set?

YES : Perform troubleshooting for the diagnostic trouble

code that is set. (Refer to

P.35C-219

NO : Go to Step 3.

STEP 3. DTC recheck after repairing the CAN bus line
Q: Is DTC U0125 set?

YES : Go to Step 4.
NO : This diagnosis is complete.

STEP 4. Connector check: A-05 ASC-ECU connector, C-46
AWC-ECU connector, C-47 intermediate connector, C-50
joint connector
Q: Is the check result normal?

YES : Go to Step 5.
NO : Repair the connector, and then go to Step 8.

STEP 5. Wiring harness check between A-05 ASC-ECU
connector terminal No. 18 and C-38 G and yaw rate sensor
connector terminal No. 2, between A-05 ASC-ECU
connector terminal No. 19 and C-38 G and yaw rate sensor
connector terminal No. 3, between C-46 AWC-ECU
connector terminal No. 9 and C-38 G and yaw rate sensor
connector terminal No. 2, between C-46 AWC-ECU
connector terminal No. 10 and C-38 G and yaw rate sensor
connector terminal No. 3

• Open or short circuit check of communication circuit

Q: Is the check result normal?

YES : Go to Step 6.
NO : Repair the wiring harness, and then go to Step 8.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-215

STEP 6. Check whether the DTC is reset.
Q: Is DTC U0125 set?

YES : Replace the G and yaw rate sensor. (Refer to

P.35C-304

.) Then go to Step 7.

NO : Intermittent malfunction. (Refer to GROUP 00 − How

to Cope with Intermittent Malfunction

P.00-15

STEP 7. Check whether the DTC is reset.
Q: Is DTC U0125 set?

YES : Replace the hydraulic unit (incorporates in

ASC-ECU). (Refer to

P.35C-298

.) Then go to Step 8.

NO : The procedure is complete.

STEP 8. Check whether the DTC is reset.
Q: Is DTC U0125 set?

YES : Return to Step 1.
NO : The procedure is complete.

DTC U0401: Engine malfunction detected

CAUTION

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

rect diagnostic trouble code may be set. Prior to this
diagnosis, diagnose the CAN bus lines.

• Whenever the ECU is replaced, ensure that the CAN

bus lines are normal.

• If diagnostic trouble code U0401 is set in ASC-ECU,

always diagnose CAN bus lines. If there is any fault in
the CAN bus lines, an incorrect DTC may be set.

• When the hydraulic unit (integrated with ASC-ECU) is

, and

CIRCUIT OPERATION

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

DTC SET CONDITIONS

This diagnostic trouble code is set when the ECM malfunction
has been detected.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-216

PROBABLE CAUSES

• Malfunction of engine system
• ECM malfunction
• ASC-ECU malfunction
• External noise interference

DIAGNOSIS

Required Special Tools:

• MB991958 Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)
• MB991827 M.U.T.-III USB Cable
• MB991910 M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus
lines.
Using scan tool MB991958, 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 −

Troubleshooting

P.54C-15

.) After repairing the CAN

bus line, go to Step 5.

STEP 2. Scan tool diagnostic trouble code
Using scan tool MB991958, check if any diagnostic trouble
code other than code No. U0401 is set in ASC-ECU.
Q: Is any DTC set?

YES : Troubleshoot the relevant diagnostic trouble code,

and then go to Step 5.

NO : Go to Step 3.

STEP 3. Diagnostic trouble code check of other system
using scan tool MB991958
Using scan tool MB991958, check if a diagnostic trouble code
is set in the engine control module.
Q: Is any DTC set?

YES : Troubleshoot the relevant diagnostic trouble code,

and then go to Step 5.

NO : Go to Step 4.

STEP 4. Check whether the DTC is reset.
Q: Is DTC U0401 set?

YES : Replace the hydraulic unit (incorporates in

ASC-ECU).(Refer to

P.35C-298

.) Then go to Step 5.

NO : Intermittent malfunction. (Refer to GROUP 00 − How

to Cope with Intermittent Malfunction

P.00-15

STEP 5. Check whether the DTC is reset.
Q: Is DTC U0401 set?