Mitsubishi Outlander GS45X. Manual - part 357

ABS DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-49

CIRCUIT OPERATION

• The wheel speed sensor is a type of pulse generator. It con-

sists of encoders (a plate on which north and south pole 
sides of the magnets are arranged alternately) for detecting 
the wheel speed which rotates at the same speed of the 
wheels and wheel speed sensors. This sensor outputs fre-
quency pulse signals in proportion to the wheel speed.

• The pulse signals, which the wheel speed sensor creates, 

are sent to ABS-ECU. ABS-ECU uses the frequency of the 
pulse signals to determine the wheel speed.

.

DTC SET CONDITIONS

ABS-ECU monitors the signals from each wheel speed sensor 
while the vehicle is being driven. If any fault below is found in 
these sensor signals, ABS-ECU will set the relevant DTC.

• Irregular change in the wheel speed sensor signal

• Wheel speed sensor signal continuously indicates higher 

value than the values of other wheel speed sensors.

.

PROBABLE CAUSES

Current trouble

• Excessive gap between the wheel speed sensor and the 

magnetic encoder for wheel speed detection

• Adhesion of foreign materials on the wheel speed sensor

• Adhesion of foreign materials on the magnetic encoder for 

wheel speed detection

• Wheel bearing malfunction

• Malfunction of wheel speed sensor

• Damaged wiring harness and connectors

• External noise interference

• Improper installation of the wheel speed sensor

• Deformation of the magnetic encoder for wheel speed 

detection

• ABS-ECU malfunction

• Disturbance of magnetization pattern for magnetic encoder 

for wheel speed detection

• The number of poles on the magnetic encoder for wheel 

speed detection (the number of N-pole and S-pole) is 
changed.

Past trouble

• When the DTC C1020 is also set, carry out diagnosis with 

particular emphasis on wiring harness and connector fail-
ures between ABS-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 DTC C1020 is not set, the following conditions 

may be present:

• Right or/and left wheels are rotated.

• Unstable vehicle attitude

• External noise interference

• Vehicle ran with the parking brake applied.

ABS DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-50

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.35B-28

).

NO :  Go to Step 4.

STEP 4. Connector check: A-01 ABS-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.

STEP 5. Wiring harness check between A-01 ABS-ECU 
connector terminal No.24 and D-114 rear wheel speed 
sensor <LH> connector terminal No.1, and between A-01 
ABS-ECU connector terminal No.25 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.

ABS DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-51

STEP 6. Check 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.35B-189

). Then go to Step 7.

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

P.35B-184

.

Q: Is the check result normal?

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

P.35B-189

). 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 wheel bearing <RL> for looseness (Refer to 
GROUP 27A 

−

 On-vehicle Service 

P.27A-6

).

Q: Is the check result normal?

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

GROUP 27A 

− Rear Axle Hub Assembly 

P.27A-8

). 

Then go to Step 12.

STEP 9. Check 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) : Replace the rear wheel hub assembly 

<RL> (Refer to GROUP 27A 

− Rear Axle Hub 

Assembly 

P.27A-8

). Then go to Step 12.

AC608763

Ball bearing

Rear hub
assembly

Magnetic
encoder

AB

ABS DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-52

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.35B-189

). 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 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 hydraulic unit (integrated with ABS-ECU) 

(Refer to 

P.35B-188

). Then go to Step 12.

NO :  The procedure is complete.

STEP 12. 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 : Return to Step 1.
NO :  The procedure is complete.