Mitsubishi Lancer Evolution X. Manual - part 156

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-89

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 C1042 set?

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

STEP 3. Wheel bearing looseness check
NOTE: Wheel bearing looseness may increase the gap 
between the wheel speed sensor and the wheel speed detec-
tion magnet encoder. Check the wheel bearing <FR> for loose-
ness. (Refer to GROUP 26 

−

 On-vehicle Service 

P.26-7

.)

Q: Is the check result normal?

YES : Go to Step 4.
NO :  Replace the front hub assembly. (Refer to GROUP 26 

− Front Axle Hub Assembly 

P.26-9

.)

STEP 4. Check of wheel speed detection encoder
Check the encoder for adhesion of foreign materials or defor-
mation.
Q: Is the check result normal?

YES  : Go to Step 5.
NO (Adhesion of foreign materials) : Clean the encoder 

so as not to disturb the magnetization pattern on the 
encoder while taking care of the magnet, magnetic 
substance, and magnetic attraction.

NO (Deformation) : Replace the front hub assembly. (Refer 

to GROUP 26 − Front Axle Hub Assembly 

P.26-9

.)

STEP 5. Check whether the DTC is reset.
(1) Erase the diagnostic trouble code.
(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 C1042 set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 6.

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

to Cope with Intermittent Malfunction 

P.00-15

.)

AC704652 AB

Oil seal

Magnetic 
encoder

Wheel 
bearing

Hub

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-90

STEP 6. Check whether the DTC is reset.
(1) Erase the diagnostic trouble code.
(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 C1042 set?

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

DTC C1043: Abnormality in periodical signal for RL wheel speed sensor

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 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

• Each wheel speed detecting section is a kind of a pulse 

generator. It consists of the encoder (plate on which the 
north and south pole of magnet are arranged alternately) for 
detecting the wheel speed, which rotates at the same speed 
of the wheels, and the wheel speed sensor. This detecting 
section outputs the frequency pulse signals in proportion to 
the wheel speed.

• The pulse signals generated by the wheel speed detecting 

section are sent to ASC-ECU. ASC-ECU uses the fre-
quency of the pulse signals to determine the wheel speed.

.

DTC SET CONDITIONS

ASC-ECU monitors the signals from each wheel speed sensor 
while the vehicle is being driven. If any periodical drop abnor-
mality is detected in the sensor signals, ASC-ECU sets the rel-
evant diagnostic trouble code.

.

PROBABLE CAUSES

• Wheel bearing malfunction
• Deformation of the magnetic encoder for wheel speed 

detection

• Adhesion of foreign materials on the magnetic encoder for 

wheel speed detection

• ABS-ECU malfunction

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-91

• Disturbance of magnetization pattern for magnetic encoder 

for wheel speed detection

• Missing teeth of the magnetic encoder for wheel speed 

detection

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

• 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 − 

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 C1043 set?

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

STEP 3. Wheel bearing looseness check
NOTE: Wheel bearing looseness may increase the gap 
between the wheel speed sensor and the wheel speed detec-
tion magnet encoder. Check the wheel bearing <RL> for loose-
ness. (Refer to GROUP 27 

−

 On-vehicle Service 

P.27-32

.)

Q: Is the check result normal?

YES : Go to Step 4.
NO :  Replace the rear wheel hub assembly. (Refer to 

GROUP 27 − Rear Axle Hub Assembly 

P.27-35

.)

STEP 4. Check of wheel speed detection encoder
Check the encoder for adhesion of foreign materials or defor-
mation.
Q: Is the check result normal?

YES  : Go to Step 5.
NO (Adhesion of foreign materials) : Clean the encoder 

so as not to disturb the magnetization pattern on the 
encoder while taking care of the magnet, magnetic 
substance, and magnetic attraction.

NO (Deformation) : Replace the rear wheel hub assembly. 

(Refer to GROUP 27 − Rear Axle Hub Assembly 

P.27-35

.)

AC608248AB

Magnetic
encoder

Rear Wheel
bearing

Rear wheel
hub
assembly

DIAGNOSIS

TSB Revision

ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-92

STEP 5. Check whether the DTC is reset.
(1) Erase the diagnostic trouble code.
(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 C1043 set?

YES : Replace the hydraulic unit (incorporates in 

ASC-ECU).(Refer to 

P.35C-298

.) Then go to Step 6.

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

to Cope with Intermittent Malfunction 

P.00-15

.)

STEP 6. Check whether the DTC is reset.
(1) Erase the diagnostic trouble code.
(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 C1043 set?

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

DTC C1044: Abnormality in periodical signal for RR wheel speed sensor

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 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

.)

.

DTC SET CONDITIONS

• Each wheel speed detecting section is a kind of a pulse 

generator. It consists of the encoder (plate on which the 
north and south pole of magnet are arranged alternately) for 
detecting the wheel speed, which rotates at the same speed 
of the wheels, and the wheel speed sensor. This detecting 
section outputs the frequency pulse signals in proportion to 
the wheel speed.

• The pulse signals generated by the wheel speed detecting 

section are sent to ASC-ECU. ASC-ECU uses the fre-
quency of the pulse signals to determine the wheel speed.

.