Mitsubishi Lancer Evolution X. Manual - part 167

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-133

CIRCUIT OPERATION

• ASC-ECU contains the power supply circuit (terminal No. 1) 

for the motor. The pump motor is energized by the pump 
motor switch, which is incorporated in ASC-ECU.

• The pump motor switch, which is incorporated in ASC-ECU, 

is always off unless the motor solenoid valve check is acti-
vated when the vehicle is started.

• ASC-ECU activates the pump motor by turning on the ECU 

built-in pump motor switch.

.

DTC SET CONDITIONS

This DTC will be set under the cases below:

• When the power supply voltage of the pump motor, which is 

not in operation, is abnormally low for a prolonged period

• When the power supply voltage of the pump motor, which is 

not in operation, is abnormally high for a prolonged period

.

PROBABLE CAUSES

Current trouble

• Fusible link malfunction
• Damaged wiring harness and connectors
• Abnormality in battery or generator
• ASC-ECU malfunction

Past trouble

• Perform the diagnosis with a particular emphasis on the wir-

ing harness and connector failures in the ASC-ECU motor 
power supply circuit (A-05 ASC-ECU connector terminal 
No. 1) and in the ground circuit (A-05 ASC-ECU connector 
terminal No. 16 and No.47). For diagnosis procedures, refer 
to How to Treat Past Trouble (GROUP 00 − How to Use 

Troubleshooting/Inspection Service Points 

P.00-16

).

DIAGNOSTIC PROCEDURE

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

• MB991997: ASC check harness

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 − 

CAN Bus Diagnosis table 

P.54C-15

). On completion, 

go to Step 2.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-134

STEP 2. DTC recheck after repairing the CAN bus line
Q: Is DTC C2116 set?

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

STEP 3. Battery check
Refer to GROUP 54A − Battery Test 

P.54A-9

.

Q: Is the battery in good condition?

YES : Go to Step 4.
NO :  Replace the battery. Then go to Step 11.

STEP 4. Charging system check
Refer to GROUP 16 − Output Current Test 

P.16-8

.

Q: Is the charging system in good condition?

YES : Go to Step 5.
NO :  Repair or replace the charging system component(s).

STEP 5. Connector check: A-05 ASC-ECU connector
Q: Is the check result normal?

YES : Go to Step 6.
NO  :  Repair the defective connector. Then go to Step 11.

STEP 6. Fusible link check: Check the fusible link No.26.
Visually check for open circuit in the fusible link No.26.
Q: Is the check result normal?

YES : Go to Step 8.
NO :  Go to Step 7.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-135

STEP 7. Resistance measurement at A-05 ASC-ECU 
connector
(1) Disconnect the ASC-ECU connector, connect the special 

tool ASC check harness (MB991997) to the wiring 
harness-side connector, and then measure the resistance 
at the special tool connector side.
NOTE: Do not connect the special tool to ASC-ECU.

(2) Disconnect the fusible link No. 26.
(3) Resistance between the terminal No. 1 and the body 

ground.

OK: No continuity

Q: Is the check result normal?

YES : Replace the fusible link No.26. Then go to Step 11.
NO :  The short circuit may be present in the power supply 

circuit. Repair the wiring harness between the A-05 
ASC-ECU connector terminal No.1 and the fusible 
link No.26, and then replace the fusible link No.26. 
Then go to Step 11.

STEP 8. Voltage measurement at the A-05 ASC-ECU 
connector
(1) Disconnect the connector, connect the special tool ASC 

check harness (MB991997) to the wiring harness-side 
connector, and measure the voltage at the special tool 
connector side.
NOTE: Do not connect the special tool to ASC-ECU.

(2) Measure the voltage between the terminal No. 1 and the 

body ground.

OK: Battery positive voltage

Q: Is the check result normal?

YES : Go to Step 9.
NO :  The open circuit may be present in the power supply 

circuit. Repair the wiring harness between the A-05 
ASC-ECU connector terminal No.1 and the fusible 
link No.26. Then go to Step 11.

AC400817 EM

ASC-ECU

MB991997

A-05 ASC-ECU 
harness connector

Check harness

AC400817CP

ASC-ECU

MB991997

A-05 ASC-ECU 
harness connector

Check harness

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-136

STEP 9. Resistance measurement at A-05 ASC-ECU 
connector
(1) Disconnect the connector, connect the special tool ASC 

check harness (MB991997) to the wiring harness-side 
connector, and then measure the voltage at the special tool 
connector side.
NOTE: Do not connect the special tool to ASC-ECU.

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

the body ground as well as between the terminal No. 47 
and the body ground.

OK: Continuity exists (2 Ω or less)

Q: Is the check result normal?

YES : Go to Step 10.
NO :  An open circuit may be present in the ground circuit. 

Repair the wiring harness between the A-05 
ASC-ECU connector terminal No.16 and the body 
ground, and between the A-05 ASC-ECU connector 
terminal No.47 and the body ground. Then go to Step 
11.

STEP 10. Check whether the DTC is reset.
(1) Erase the DTC.
(2) Drive the vehicle at 12mph (20 km/h) or more.

NOTE: The ABS warning light does not turn OFF in some 
cases unless the vehicle runs at 12mph (20 km/h) or higher.

Q: Is DTC C2116 set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 11.

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

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 11. Check whether the DTC is reset.
(1) Erase the DTC.
(2) Drive the vehicle at 12mph (20 km/h) or more.

NOTE: The ABS warning light does not turn OFF in some 
cases unless the vehicle runs at 12mph (20 km/h) or higher.

Q: Is DTC C2116 set?

YES : Return to Step 1.
NO :  This diagnosis is complete.

AC400817CO

ASC-ECU

MB991997

A-05 ASC-ECU 
harness connector

Check harness