Mitsubishi Lancer Evolution X. Manual - part 172

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-153

STEP 15. Measure the voltage at C-48 stoplight switch 
connector.
(1) Disconnect C-48 stoplight switch connector, and measure 

the voltage at harness connector side.

(2) Measure the voltage between the terminal No.2 and the 

body ground.

OK: Battery positive voltage

Q: Is the check result normal?

YES : Go to Step 16.
NO :  An open circuit may be present in the wiring harness 

between C-304 ETACS-ECU connector terminal No. 
1 and C-48 stoplight switch connector terminal No. 2. 
Repair the wiring harness.

STEP 16. Connector check: C-43 joint connector
Q: Is the check result normal?

YES : Go to Step 17.
NO :  Repair the damaged connector.

STEP 17. Voltage measurement at C-43 joint connector

CAUTION

Measure while the brake pedal is depressed.
(1) Disconnect the connector, and measure at the wiring 

harness side.

(2) Measure the voltage between the terminal No.2 and the 

body ground.

OK: Battery positive voltage

Q: Is the check result normal?

YES : Go to Step 18.
NO :  An open circuit may be present in the wiring harness 

between C-43 joint connector terminal No.2 and C-48 
stoplight switch connector terminal No.1. Repair the 
wiring harness.

STEP 18. Connector check: C-312 ETACS-ECU connector
Q: Is the check result normal?

YES : Go to Step 19.
NO :  Repair the damaged connector.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-154

STEP 19. Measure the voltage at the C-312 ETACS-ECU 
connector.
(1) Measure by backprobing without disconnecting the 

connector.

(2) Measure the voltage between the terminal No.16 and the 

body ground.

OK:

When the brake pedal is released: 0 V - 5V (pulse)
When the brake pedal is depressed: Approxi-

mately battery positive voltage

Q: Is the check result normal?

YES : Go to Step 22.
NO :  Go to Step 20.

STEP 20. Check the wiring harness between C-312 
ETACS-ECU connector terminal No.16 and C-48 stoplight 
switch connector terminal No.1

• Check the signal line for open circuit.

Q: Is the check result normal?

YES : Go to Step 21.
NO :  Replace the wiring harness.

STEP 21. Diagnostic trouble code recheck
Q: Is diagnostic trouble code No.C1000 set?

YES : Replace the hydraulic unit (ASC-ECU) (Refer to 

P.35C-298

). Then go to Step 23.

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

Cope with Intermittent Malfunction 

P.00-15

.)

STEP 22. Check whether the DTC is reset.
Q: Is DTC 1000 set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 23.

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

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 23. Check whether the DTC is reset.
Q: Is DTC 1000 set?

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

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-155

DTC C123B: Prolonged operation of ASC

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.

• When the steering wheel sensor is replaced or 

re-installed, always perform the calibration to make 
ASC-ECU learn the neutral point. (Refer to 

P.35C-289

.)

• 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, always perform the calibration of steering 
wheel sensor, G and yaw rate sensor, brake fluid pres-
sure sensor, cut valve, and inlet valve.(Refer to 

P.35C-287

, 

P.35C-289

, 

P.35C-294

, and 

P.35C-295

.)

.

CIRCUIT OPERATION

ASC-ECU controls ASC by calculating the data sent from the 
wheel speed sensor, steering wheel sensor, and G and yaw 
rate sensor.

.

DTC SET CONDITIONS

This diagnostic trouble code is set when ASC control is oper-
ated for a prolonged period.
NOTE: This diagnostic trouble code may be set when the vehi-
cle runs on a slippery or rough road, or when the vehicle per-
forms a steady state cornering.

.

PROBABLE CAUSES

• Steering wheel sensor malfunction
• G and yaw rate sensor malfunction
• Improper installation of steering wheel sensor or G and yaw 

rate sensor

• ASC-ECU malfunction
• Different steering wheel
• Wheel alignment not performed

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

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-156

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 3.
NO :  Repair the CAN bus lines. (Refer to GROUP 54C − 

Troubleshooting 

P.54C-15

.) After repairing the CAN 

bus line, go to Step 2.

STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C123B set?

YES : Go to Step 3.
NO :  This diagnosis is complete.

STEP 3. Scan tool diagnostic trouble code
Check that DTCs C100A, C1015, C1020, C102B, C1011, 
C101C, C1027, C1032, C1014, C101F, C102A, C1035, C1041, 
C1042, C1043, C1044, C1219, C2205, C123C, and C2204 are 
also set.
Q: Are DTCs C100A, C1015, C1020, C102B, C1011, C101C, 

C1027, C1032, C1014, C101F, C102A, C1035, C1041, 
C1042, C1043, C1044, C1219, C2205, C123C, and C2204 
also set?
YES : Carry out the diagnosis for the diagnostic trouble 

code that is set. (Refer to 

P.35C-22

.) Then go to Step 

10.

NO :  Go to Step 4.

STEP 4. Check of G and yaw rate sensor installation status
Check that the G and yaw rate sensor is installed correctly.
Q: Is the check result normal?

YES : After checking the G and yaw rate sensor, perform 

the calibration of the G and yaw rate sensor to make 
ASC-ECU relearn the neutral point.(Refer to 

P.35C-287

.) Then go to Step 5.

NO :  Reinstall the G and yaw rate sensor correctly. (Refer 

to 

P.35C-304

.) Then go to Step 10.

STEP 5. Scan tool service data
Check the following service data. (Refer to 

P.35C-276

.)

• Item 08: Lateral G sensor
• Item 09: G sensor
• Item 12: Yaw rate sensor

Q: Is the check result normal?

YES : Go to Step 6.
NO :  Replace the G and yaw rate sensor. (Refer to 

P.35C-304

.) Then go to Step 10.