Mitsubishi Outlander GS45X. Manual - part 407

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

35C-55

Past trouble

• When the diagnostic trouble code No. C1020 is also set, 

carry out diagnosis with particular emphasis on wiring har-
ness and connector failures between ASC-ECU and the 
wheel speed sensor. For diagnosis procedures, refer to 
How to treat past trouble (Refer to GROUP 00 

− How to 

Use Troubleshooting/How to Treat Past Trouble 

P.00-17

).

• When the diagnostic trouble code No. C1020 is not set, the 

following conditions may be present:

• Some wheels slip

• Unstable vehicle attitude

• External noise interference

• Vehicle ran with the parking brake applied.

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.
Use scan tool 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 

P.54C-17

). On 

completion, go to Step 2.

STEP 2. DTC recheck after resetting CAN bus lines
Q: Is DTC C1027 set?

YES : Go to Step 3.
NO :  The procedure is complete.

STEP 3. Using scan tool MB991958, check the DTC
Check that the DTC C1020 is also set.
Q: Is DTC C1020 also set?

YES : Perform the diagnosis for the DTC C1020 (Refer to 

P.35C-32

).

NO :  Go to Step 4.

STEP 4. Connector check: A-02 ASC-ECU connector, 
C-129 intermediate connector, D-114 rear wheel speed 
sensor <LH> connector
Q: Is the check result normal?

YES : Go to Step 5.
NO :  Repair the defective connector. Then go to Step 12.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

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STEP 5. Wiring harness check between A-03 ASC-ECU 
connector terminal No.36 and D-114 rear wheel speed 
sensor <LH> connector terminal No.1, and between A-03 
ASC-ECU connector terminal No.37 and D-114 rear wheel 
speed sensor <LH> connector terminal No.2.
Q: Is the check result normal?

YES : Go to Step 6.
NO :  Repair the wiring harness. Then go to Step 12.

STEP 6. Check for wheel speed sensor <RL> installation
Check how the wheel speed sensor <RL> is installed (Discon-
nection of wheel speed sensor <RL>, loose mounting bolt, 
etc.).
Q: Is the check result normal?

YES : Go to Step 7.
NO :  Reinstall the wheel speed sensor <RL> correctly 

(Refer to 

P.35C-288

). Then go to Step 7.

STEP 7. Check for wheel speed sensor <RL> output 
current
Refer to 

P.35C-277

.

Q: Is the check result normal?

YES : Go to Step 8.
NO :  Replace the wheel speed sensor <RL> (Refer to 

P.35C-288

). Then go to Step 11.

STEP 8. Check for wheel bearing looseness
NOTE: 

.

•

Loose wheel bearing may increase the gap between the 
wheel speed sensor <RL> and the wheel speed detection 
magnet encoder.

•

Check the Rear wheel hub assembly <RL (FWD)> (Refer to 
GROUP 27A 

−

 Wheel Bearing Play Check 

P.27A-6

).

•

Check the wheel bearing <RL (AWD)> for looseness (Refer 
to GROUP 27B 

−

 Wheel Bearing Play Check 

P.27B-17

).

Q: Is the check result normal?

YES : Go to Step 9.
NO (FWD) : Replace the rear wheel hub assembly <RL> 

(Refer to GROUP 27A 

− Rear axle hub assembly 

P.27A-8

). Then go to Step 12.

NO (AWD) : Replace the wheel bearing <RL> (Refer to 

GROUP 27B 

− Rear axle hub assembly 

P.27B-19

). 

Then go to Step 12.

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

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STEP 9. 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 10.
NO (Adhesion of foreign materials) : Remove the foreign 

materials and clean the encoder so as not to disturb 
the magnetization pattern on it while taking care of the 
magnet, magnetic substance, and magnetic 
attraction. Then go to Step 12.

NO <Deformation (FWD)> : Replace the rear wheel hub 

assembly <RL> (Refer to GROUP 27A 

− Rear axle 

hub assembly 

P.27A-8

). Then go to Step 12.

NO <Deformation (AWD)> : Replace the wheel bearing 

<RL> (Refer to GROUP 27B 

− Rear axle hub 

assembly 

P.27B-19

). Then go to Step 12.

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

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 C1027 set?

YES : Replace the wheel speed sensor <RL> (Refer to 

P.35C-288

). Then go to Step 11.

NO :  Intermittent malfunction (Refer to GROUP 00 

− How 

to Use Troubleshooting/How to Cope with Intermittent 
Malfunctions 

P.00-15

).

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

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

Q: Is DTC C1027 set?

YES : Replace the hydraulic unit (integrated with ASC-ECU) 

(Refer to 

P.35C-287

). Then go to Step 12.

NO :  The procedure is complete.

AC704785

Rear hub

Oil seal

Ball bearing

Magnetic
encoder

AB

Magnetic
encoder

Rear hub
assembly

Rear wheel bearing

<FWD>

<AWD>

DIAGNOSIS

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ACTIVE STABILITY CONTROL SYSTEM (ASC)

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

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

Q: Is DTC C1027 set?

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

DTC C1032: Abnormality in RR wheel speed sensor signal

Wheel Speed Sensor Circuit

ASC-ECU

FRONT 
WHEEL 
SPEED 
SENSOR 
(LH)

FRONT 
WHEEL 
SPEED 
SENSOR 
(RH)

REAR 
WHEEL 
SPEED 
SENSOR 
(LH)

REAR 
WHEEL 
SPEED 
SENSOR 
(RH)

AC901112

Connector: A-02

A-02 (B)

AF

AC901075BC

Connector: C-129