Mitsubishi Montero (2004+). Manual - part 1056

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-67

STEP 3. Check the harness wire between the valve relay 
connector B-21X terminal 2 and M-ASTC-ECU connector 
E-120 terminal 62.
Q: Is the harness wire between the valve relay connector 

B-21X terminal 2 and M-ASTC-ECU connector E-120 
terminal 62 damaged?
YES : Repair it and then go to Step 5.
NO :  Go to Step 4.

AC204706

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B-21X

CONNECTOR: B-21X

AB

RELAY BOX CONNECTOR

AC203901

AC204627AG

CONNECTOR: E-120

E-120

HARNESS CONNECTOR: 
COMPONENT SIDE

E-120

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-68

STEP 4. Check the harness wire between the valve relay 
connector B-21X terminal 4 and ground.
Q: Is the harness wire between the valve relay connector 

B-21X terminal 4 and ground damaged?
YES : Repair it and then go to Step 5.
NO :  Replace the M-ASTC-ECU and go to Step 5.

STEP 5. Recheck for diagnostic trouble code.
Q: Does DTC 51 reset?

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

DTC 52: Valve Relay System (Open Circuit or OFF Failure)

.

VALVE RELAY CIRCUIT
 Refer to 

P.35B-64

.

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CIRCUIT OPERATION
As the ignition switch is turned ON, M-ASTC-ECU 
drives the valve relay in a series of ON

→OFF→ON 

with the initial check in order to inspect the valve 
relay for normal operation. It then maintains the valve 
relay always at ON and supplies power to each sole-
noid valve.

.

ABS DTC SET CONDITIONS
DTC 52 is set if the M-ASTC-ECU judges that there 
is a valve relay OFF problem when the valve relay is 
on and power is not supplied to the solenoid valves. 

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TROUBLESHOOTING HINTS

• Malfunction of the valve relay

• Malfunction of the M-ASTC-ECU

• Damaged wiring harness or connector

.

DIAGNOSIS

Required Special Tools:

•  MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

• MB991223: Harness Set

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B-21X

CONNECTOR: B-21X

RELAY BOX CONNECTOR

AC204706

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AC

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-69

STEP 1. Check the valve relay.

Q: Is the relay damaged?

YES : Replace it and go to Step 10.
NO :  Go to Step 2.

STEP 2. Check the valve relay circuit at M-ASTC-ECU 
connector E-119 by backprobing.
(1) Do not disconnect connector E-119.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 18 and ground by 

backprobing. It should be less than 2V.

Q: Is the voltage less than 2V?

YES : Go to Step 3.
NO :  Go to Step 5. 

BATTERY VOLTAGE

TESTER 
CONNECTION

SPECIFIED 
CONDITION

Not applied

2 

− 4

Less than 2 
ohms

2 

− 5

Open circuit

• Connect terminal 1 to the 

positive battery terminal

• Connect terminal 3 to the 

negative battery terminal

2 

− 4

Open circuit

2 

− 5

Less than 2 
ohms

AC204274

AB

VALVE RELAY

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5

AC203901AE

CONNECTOR: E-119

E-119

AC204705

HARNESS CONNECTOR:
COMPONENT SIDE

AB

E-119

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-70

STEP 3. Check the valve relay monitor circuit at 
M-ASTC-ECU connector E-120 by backprobing.
(1) Do not disconnect connector E-120.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 55 and ground by 

backprobing. It should be approximately 12 volts (battery 
positive voltage).

Q: Is the voltage approximately 12 volts (battery positive 

voltage)?
YES : Go to Step 4.
NO :  Go to Step 6. 

STEP 4. Check the M-ASTC-ECU connector E-120.
Q: Is the connector damaged?

YES : Repair it. Refer to GROUP 00E, Harness Connector 

Inspection 

P.00E-2

. Then go to Step 10.

NO :  Replace the M-ASTC-ECU and go to Step 10. 

STEP 5. Check the harness wire between ignition switch 
(IG2) connector D-208 terminal 4 and M-ASTC-ECU 
connector E-119 terminal 18.
NOTE:  After inspecting ignition switch (IG2) connector D-208 
and M-ASTC-ECU connector E-119, valve relay connector 
B-21X, joint connector D-116, junction block connectors D-208, 
D-212 and intermediate connector E-111, inspect the wire. If 
ignition switch (IG2) connector D-208 and M-ASTC-ECU con-
nector E-106, valve relay connector B-21X, joint connector 
D-116, junction block connectors D-208, D-212 and intermedi-
ate connector E-111 are damaged, repair or replace them. 
Refer to GROUP 00E, Harness Connector Inspection 

P.00E-2

. 

If the connector has been repaired or replaced, go to Step 10.

AC203901AF

CONNECTOR: E-120

E-120

AC205737

CONNECTOR: E-120

E-120

AB

HARNESS CONNECTOR: 
HARNESS SIDE

AC203901AF

CONNECTOR: E-120

E-120