Mitsubishi Montero (2002-2004). Manual - part 1058

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-103

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CIRCUIT OPERATION
The ABS warning light power is supplied from the 
ignition switch. The M-ASTC-ECU grounds the circuit 
to illuminate the light. The light also illuminates when 
the valve relay is switched to OFF.

.

TECHNICAL DESCRIPTION (COMMENT)
The M-ASTC-ECU uses the power supply which is 
turned off when the ignition switch is turned to 
"START" position. The ABS warning light uses the 
power supply which is not turned off when the igni-
tion switch is turned to the "START" position. Accord-

ingly, when the ignition switch is turned to the 
"START" position, the power supply to the M-ASTC-
ECU is turned off and the valve relay is also turned 
off. So, when the ABS warning light does not illumi-
nate at this time, the light illumination circuit in the 
valve relay system is defective.

.

TROUBLESHOOTING HINTS (The most likely 
causes for this condition:)

• Damaged wiring harness

• Malfunction of valve relay

• Malfunction of M-ASTC-ECU

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DIAGNOSIS

Required Special Tool:

• MB991223: Harness Set

STEP 1. Check the valve relay.

Q: Is the relay damaged?

YES : Replace the part. Then go to Step 4.
NO :  Go to Step 2.

AC204385

CONNECTORS: E-108, E-110

AE

E-110

E-108(B)

BATTERY VOLTAGE

TESTER 
CONNECTION

SPECIFIED 
CONDITION

Not applied

2 

− 4

Less than 2 
ohms

• Connect terminal 1 to the 

positive battery terminal

• Connect terminal 3 to the 

negative battery terminal

Open circuit

AC204674

AC204762

AB

B-21X (VALVE RELAY)

CONNECTOR: B-21X

2

1

3

5

4

1 4

5

2

3

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-104

STEP 2. Check the harness wire between combination 
meter connector D-03 terminal 56 and valve relay 
connector B-21X terminal 2.
NOTE: After inspecting valve relay connector B-21X and inter-
mediate connector E-110, inspect the wire. If valve relay con-
nector B-21X and intermediate connector E-110 are damaged, 
repair or replace them. Refer to GROUP 00E, Harness Con-
nector Inspection 

P.00E-2

.Then go to Step 4.

Q: Is the harness wire between combination meter 

connector D-03 terminal 56 and valve relay connector B-
21X terminal 2 damaged?
YES : Repair it and then go to Step 4.
NO :  Go to Step 3.

AC204690 AC

CONNECTOR: D-03

D-03 (GR)

HARNESS CONNECTOR: 
COMPONENT SIDE

D-03

AC204706

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

5

B-21X

CONNECTOR: B-21X

AB

RELAY BOX CONNECTOR

AC204385

CONNECTOR: E-110

AD

E-110

6

1

7

2

9

8

10

3

5

12

11

4

1314

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-105

STEP 3. Check the harness wire between valve relay 
connector B-21X terminal 4 and ground.
NOTE: After inspecting valve relay connector B-21X, inspect 
the wire. If valve relay connector B-21X is damaged, repair or 
replace it. Refer to GROUP 00E, Harness Connector Inspec-
tion 

P.00E-2

.Then go to Step 4.

Q: Is the harness wire between valve relay connector B-

21X terminal 4 and ground damaged?
YES : Repair it and then go to Step 4.
NO :  This malfunction is intermittent. Refer to GROUP 00, 

How to Use Troubleshooting/Inspection Service 
Points 

− How to Cope With Intermittent Malfunction 

P.00-6

.

STEP 4. Retest the system.
Q: Does the ABS warning light illuminate when the ignition 

switch is turned to the "START" position?
YES : The procedure is complete.
NO :  Return to Step 1.

AC204706

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

4

1

2

3

5

B-21X

CONNECTOR: B-21X

AB

RELAY BOX CONNECTOR

AC203935

AC

GROUND POINT

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-106

INSPECTION PROCEDURE 5: The ABS Warning Light Flashes Twice after the Ignition Switch is 
Turned to the "On" Position. The Light Illuminates When the Ignition Switch is Turned to the "Start" 
Position, and When the Ignition Switch is Returned to the "On" Position, it Flashes Once.

AC204875AB

ABS Warning Light Circuit

AC204674

AB

B-21X (VALVE RELAY)

CONNECTOR: B-21X

AC204547AC

CONNECTORS: D-208, D-210

D-208

D-210

JUNCTION BLOCK
(FRONT VIEW)

AC204546 AB

CONNECTOR: D-03

D-03 (GR)

AC203901AF

CONNECTOR: E-120

E-120