Mitsubishi Montero (2002-2004). Manual — part 1047

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-59

.

CIRCUIT OPERATION
As the ignition switch is turned ON, the 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 solenoid valve.

.

ABS DTC SET CONDITIONS
DTC 51 is set when the M-ASTC-ECU judges during
the initial check when the ignition switch is turned to
the ON position and the valve relay is OFF that there
is a fused relay contact or a short-circuit in the valve
relay drive circuit when power is being supplied to
the solenoid valve.

.

TROUBLESHOOTING HINTS

• Malfunction of the valve relay

• Malfunction of the M-ASTC-ECU

• Damaged wiring harness or connector

.

AC204545 AC

CONNECTORS: B-17, B-18

B-17 (GR)

B-18 (B)

AC204674

AB

B-21X (VALVE RELAY)

CONNECTOR: B-21X

AC204675AB

D-116

CONNECTOR: D-116

AC204547AB

CONNECTORS: D-208, D-212

D-208

D-212

JUNCTION BLOCK
(FRONT VIEW)

AC204548AL

E-111

CONNECTORS: E-108, E-111

E-108

AC203901AD

CONNECTORS: E-119, E-120

E-119

E-120

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-60

DIAGNOSIS

Required Special Tool:

• MB991223: Harness Set

STEP 1. Check the valve relay.

Q: Is the relay damaged?

YES : Replace it and go to Step 5.
NO : Go to Step 2.

STEP 2. Check the valve relay circuit at M-ASTC-ECU
connector E-119.
(1) Disconnect connector E-119 and measure at the harness

side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 18 and ground. It

should be approximately 12 volts (battery positive voltage).

Q: Is the voltage approximately 12 volts (battery positive

voltage)?
YES : Go to Step 3.
NO : Repair it because of short circuit to ground between

the valve relay and M-ASTC-ECU. Then 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

2

1

3

5

4

1

3

2

4
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-61

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

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

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-62

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-58

.

.

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.

.

TROUBLESHOOTING HINTS

• Malfunction of the valve relay

• Malfunction of the M-ASTC-ECU

• Damaged wiring harness or connector

.

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

RELAY BOX CONNECTOR

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

AC