Mitsubishi Montero (2004+). Manual — part 1015

HYDRAULIC BRAKE BOOSTER (HBB) DIAGNOSIS

TSB Revision

BASIC BRAKE SYSTEM

35A-59

.

CIRCUIT OPERATION

• The pump motor operates if the motor relay A or

motor relay B turn to ON.

• The M-ASTC-ECU monitors the pump motor (at

25 terminal).

.

HBB DTC SET CONDITIONS
DTC 55 will be set when the pump motor has been
energized too long. The M-ASTC-ECU sounds the
buzzer continuously to inform the trouble of the driver
and protects the pump motor by activating the pump
motor intermittently.

.

TROUBLESHOOTING HINTS

• Malfunction of the motor relay A or the motor

relay B

• Malfunction of the pressure switch (for pump

motor control) [Integrated with the hydraulic
brake booster (HBB)]

• Damaged wiring harness or connector

• Malfunction of the M-ASTC-ECU

.

DIAGNOSIS

Required Special Tool:

• 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

AC204545 AC

CONNECTORS: B-17, B-18

B-17 (GR)

B-18 (B)

AC204329 AC

CONNECTORS: B-53X, B-54X

B-53X

B-54X

AC204688 AB

CONNECTOR: D-116

D-116

AC204547AB

CONNECTORS: D-208, D-212

D-208

D-212

JUNCTION BLOCK
(FRONT VIEW)

AC204548 AB

CONNECTOR: E-111

E-111

AC203901AD

CONNECTORS: E-119, E-120

E-119

E-120

HYDRAULIC BRAKE BOOSTER (HBB) DIAGNOSIS

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BASIC BRAKE SYSTEM

35A-60

• MB991223: Harness Set

STEP 1. Check the pump motor operation.

Remove the motor relay A.
Q: Does the pump motor stop?

YES : Remove the motor relay A. Then go to Step 15.
NO : Go to Step 2.

STEP 2. Check the pump motor operation.

Remove the motor relay B.
Q: Does the pump motor stop?

YES : Remove the motor relay B. Then go to Step 15.
NO : Go to Step 3.

AC204329 AD

MOTOR
RELAY A

AC204329 AE

MOTOR
RELAY B

HYDRAULIC BRAKE BOOSTER (HBB) DIAGNOSIS

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BASIC BRAKE SYSTEM

35A-61

STEP 3. Check the power supply circuit at HBB harness
connector B-18.

(1) Disconnect HBB connector B-18.

(2) Measure the voltage between terminal 31 and ground. The

voltage should measure 0 volt.

Q: Is the measured voltage 0 volt?

YES : Go to Step 5.
NO : Go to Step 4.

AC204629 AD

CONNECTOR: B-18

B-18 (B)

HBB CONNECTOR

B-18

AC204632

34

32

31

33

35

AB

HARNESS CONNECTOR:
COMPONENT SIDE

B-18 (B)

HYDRAULIC BRAKE BOOSTER (HBB) DIAGNOSIS

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BASIC BRAKE SYSTEM

35A-62

STEP 4. Check the following harness wire.

• The wire between motor relay A connector B-53X (terminal

4) and HBB connector B-18 (terminal 31)

Q: Is the harness wire damaged?

YES : Repair or replace it and then go to Step 15.
NO : Go to Step 15.

AC204551

3 2 1

5 4

1 2 3

4 5

RELAY BOX CONNECTOR

AC

CONNECTOR: B-53X

B-53X

AC204626 AB

CONNECTOR: B-18

B-18 (B)

HARNESS CONNECTOR :
COMPONENT SIDE

34

32

31

33

35

B-18