Mitsubishi Outlander GS45X. Manual - part 352

ABS DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-29

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 voltage fluctuation in each wheel speed 
sensor circuit. If ABS-ECU detects the open or short circuit in 
the circuit, it will set a DTC.

.

PROBABLE CAUSES

Current trouble

• Damaged wiring harness and connectors

• Noise interference

• Malfunction of wheel speed sensor

• ABS-ECU malfunction

Past trouble

• Carry out diagnosis with particular emphasis on wiring har-

ness and connector failures 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

).

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

• MB991974: ABS check harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus 
line.
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-10

). On 

completion, go to Step 2.

STEP 2. DTC recheck after resetting CAN bus lines
Q: Is the DTC C1020 set?

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

ABS DIAGNOSIS

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ANTI-LOCK BRAKING SYSTEM (ABS)

35B-30

STEP 3. Scan tool data list
Check the following data list (Refer to 

P.35B-179

).

• Item No.03: RL wheel speed sensor

Q: Is the check result normal?

YES : Go to Step 12.
NO :  Go to Step 4.

STEP 4. Voltage measurement at the A-01 ABS-ECU 
connector
(1) Disconnect the ABS-ECU connector, connect special tool 

ABS check harness (MB991974) to the harness-side 
connector, and then measure the voltage at the special tool 
connector side.
NOTE: Do not connect the special tool ABS check harness 
(MB991974) to ABS-ECU.

(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between the rear wheel speed sensor 

<LH> power supply terminal (signal terminal) No.24 and 
body ground, and between the wheel speed sensor ground 
terminal No.25 and body ground.

OK: 1 volt or less

Q: Is the check result normal?

YES : Go to Step 5.
NO (Not normal at the terminal No.24 or No.25) : Go to 

Step 6.

AC611137AR

ABS-ECU

MB991974

A-01 ABS-ECU  
harness connector

Check harness

ABS DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-31

STEP 5. Resistance measurement at A-01 ABS-ECU 
connector
(1) Disconnect the ABS-ECU connector, connect special tool 

ABS check harness (MB991974) to the harness-side 
connector, and then measure the resistance at the special 
tool connector side.
NOTE: Do not connect the special tool ABS check harness 
(MB991974) to ABS-ECU.

(2) Measure the resistance between the rear wheel speed 

sensor <LH> power supply terminal (signal terminal) No.24 
and body ground, and between the ground terminal No.25 
and body ground.

OK: No continuity

Q: Is the check result normal?

YES : Go to Step 8.
NO (Not normal at the terminal No.24 or No.25) : Go to 

Step 6.

STEP 6. 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 7.
NO :  Repair the defective connector. Then go to Step 13.

STEP 7. 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.

• Check for short circuit in rear wheel speed sensor <LH> cir-

cuit

Q: Is the check result normal?

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

P.35B-189

). Then go to Step 13.

NO :  Repair the wiring harness. Then go to Step 13.

AC611137BQ

ABS-ECU

MB991974

A-01 ABS-ECU  
harness connector

Check harness

ABS DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-32

STEP 8. Voltage measurement at the A-01 ABS-ECU 
connector
(1) Disconnect the ABS-ECU connector, connect special tool 

ABS check harness (MB991974) to the ABS-ECU-side 
connector and harness-side connector, and then measure 
the voltage at the special tool connector side.

(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between the rear wheel speed sensor 

<LH> power supply terminal (signal terminal) No.24 and 
body ground, and between the ground terminal No.25 and 
body ground.

OK:

Terminal No.24 and body ground: Approximately 

system voltage

Terminal No.25 and body ground: 1 volt or less

Q: Is the check result normal?

YES : Go to Step 9.
NO :  Go to Step 11.

STEP 9. 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.

• Check for open circuit in rear wheel speed sensor <LH> cir-

cuit

Q: Is the check result normal?

YES : Go to Step 10.
NO :  Repair the wiring harness.

STEP 10. Check for wheel speed sensor <RL> as a single 
unit
Refer to 

P.35B-193

.

Q: Is the check result normal?

YES : Go to Step 11.
NO :  Replace the wheel speed sensor <RL> (Refer to 

P.35B-189

). Then go to Step 13.

STEP 11. 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 12.
NO :  Repair the defective connector. Then go to Step 13.

AC611138AH

ABS-ECU

MB991974

A-01 ABS-ECU 
harness connector

Check harness