Mitsubishi Montero (2002-2004). Manual — part 1033

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-3

System Check Sound

When starting the engine, a thudding sound can
sometimes be heard coming from the engine com-
partment. This is a normal sound during the ABS
self-check.

ABS Operation Sounds and Sensations

During normal operation, the ABS makes several
sounds that may seem unusual at first:

• A whining sound is caused by the ABS hydraulic

unit motor.

• When pressure is applied to the brake pedal, the

pulsation of the pedal causes a scraping sound.

• When the brakes are applied firmly, the ABS

operates, rapidly applying and releasing the
brakes many times per second. This repeated
application and release of braking forces can
cause the suspension to make a thumping sound
and the tires to squeak.

Long Stopping Distances on Loose Road
Surfaces

When braking on loose surfaces like snow-covered
or gravel roads, the stopping distance can be longer
for an ABS-equipped vehicle than the stopping dis-
tance for a vehicle with a conventional brake system.

Shock at starting check

Shock may be felt when the brake pedal is lightly
pressed while driving at a low speed. This is a nor-
mal characteristic because the ABS system opera-
tion check is carried out when vehicle speed is 8 km/
h (5 mph) or less.

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

INTRODUCTION TO ANTI-LOCK BRAKING SYSTEM DIAGNOSIS

M1352012500318

The anti-lock brake system (ABS) operates differ-
ently from conventional brake systems. These differ-
ences include sounds, sensations, and vehicle
performance that owners and service technicians
who are not familiar with ABS may not be used to.
Some operational characteristics may seem to be
malfunctions, but they are simply signs of normal
ABS operation. When diagnosing the ABS system,
keep these operational characteristics in mind.
Inform the owner of the kind of performance charac-
teristics to expect from an ABS-equipped vehicle.

ABS Diagnostic Trouble Code Detection
Conditions

ABS diagnostic trouble codes (ABS DTCs) are set
under different conditions, depending on the mal-
function detected. Most ABS DTCs will only be set
during vehicle operation. Some ABS DTCs will also
be set during the ABS self-check immediately after
the engine is started.
When you check if an ABS DTC will be displayed
again after the DTC has been erased, you should
duplicate the ABS DTC set conditions. Depending on
the detection timing and set conditions for the spe-
cific ABS DTC, you must either drive the vehicle or
turn the engine off and restart it. To set the proper
conditions for that DTC again, refer to "ABS DTC
SET CONDITIONS" for each ABS DTC that you are
trying reset.

TROUBLESHOOTING STRATEGY

M1352011100395

Use these steps to plan your diagnostic strategy. If
you follow them carefully, you will be sure that you
have exhausted most of the possible ways to find an
ABS fault.
1. Gather information about the problem from the

customer.

2. Verify that the condition described by the

customer exists.

3. Check the vehicle for any ABS DTC.

4. If you cannot verify the condition and there are no

ABS DTCs, the malfunction is intermittent. Refer
to GROUP 00, How to use Troubleshooting/
Inspection Service Points

− How to Cope with

Intermittent Malfunctions

P.00-6

.

5. If you can verify the condition but there are no

ABS DTCs, or the system cannot communicate
with the scan tool, check that the basic brake
system is operating properly.

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-4

• If the basic brake system is not operating prop-

erly, refer to the GROUP 35A, Basic Brake Sys-
tem Diagnosis

P.35A-6

.

• If the basic brake system is operating properly,

refer to

P.35B-80

.

6. If there is an ABS DTC, record the number of the

DTC, then erase the DTC from the memory using
the scan tool.

7. Duplicate the ABS DTC set conditions to see if the

same ABS DTC will set again.

• If the same ABS DTC sets again, perform the

diagnostic procedures for the DTC. Refer to

P.35B-5

.

• If you cannot get the same ABS DTC to set

again, the malfunction is intermittent. Refer to
GROUP 00, How to use Troubleshooting/Inspec-
tion Service Points

− How to Cope with Intermit-

tent Malfunctions

P.00-6

.

TROUBLE CODE DIAGNOSIS

M1352011200392

Retrieving ABS Diagnostic Trouble Codes

.

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Use scan tool MB991502 to check for ABS diagnostic

trouble codes.

4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Disconnect scan tool MB991502.

Erasing ABS Diagnostic Trouble Codes

.

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Use scan tool MB991502 to erase ABS diagnostic trouble

codes.

4. Turn the ignition switch to the "LOCK" (OFF) position.
5. Disconnect scan tool MB991502.

ACX01539AE

MB991502

16-PIN

ACX01539AE

MB991502

16-PIN

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-5

DIAGNOSTIC TROUBLE CODE CHART

M1352011300407

Follow the inspection chart that is appropriate for the
diagnostic trouble code.

DIAGNOSTIC
TROUBLE
CODE NO.

INSPECTION ITEM

DIAGNOSTIC CONTENT

REFERENCE PAGE

11

Front right ABS sensor

Open circuit or short circuit

P.35B-8

12

Front left ABS sensor

13

Rear right ABS sensor

14

Rear left ABS sensor

16

Battery positive voltage

M-ASTC-ECU power
supply voltage is extremely
low or high

Refer to GROUP 35A,
HBB Trouble Code
Diagnosis

P.35A-16

.

17

Active skid control switch

Abnormal output signal

Refer to GROUP 35C,
Active skid control system
Trouble Code Diagnosis

P.35C-7

.

21

Front right ABS sensor

P.35B-20

22

Front left ABS sensor

23

Rear right ABS sensor

24

Rear left ABS sensor

25

The difference diameter tire

P.35B-32

31

Ignition switch (IG2) system

Open circuit

Refer to GROUP 35A,
ABS Trouble Code
Diagnosis

P.35A-18

.

33

Stoplight switch system

Open circuit or ON failure

P.35B-36

34

CAN communication system

Refer to GROUP 35C,
Active skid control system
Trouble Code Diagnosis

P.35C-13

.

35

PCM (engine) system

Abnormal output signal

Refer to GROUP 35C,
Active skid control system
Trouble Code Diagnosis

P.35C-15

.

36

Communication line with PCM (engine)

Refer to GROUP 35C,
Active skid control system
Trouble Code Diagnosis

P.35C-17

.

37

PCM (A/T) system

Abnormal output signal

Refer to GROUP 35C,
Active skid control system
Trouble Code Diagnosis

P.35C-15

.

38

Communication line with PCM (A/T)

Refer to GROUP 35C,
Active skid control system
Trouble Code Diagnosis

P.35C-17

.

ANTI-LOCK BRAKING SYSTEM (ABS) DIAGNOSIS

TSB Revision

ANTI-LOCK BRAKING SYSTEM (ABS)

35B-6

41

Front right control solenoid
valve

If there is no response to
the solenoid valve drive
signal corresponding to
each respective item

P.35B-43

42

Front left control solenoid valve

43

Rear right control solenoid valve

44

Rear left control solenoid valve

45

Front right select solenoid valve

46

Front left select solenoid valve

47

Active traction control system select solenoid valve

Refer to GROUP 35C,
Active skid control system
Trouble Code Diagnosis

P.35C-19

.

48

Active traction control system select solenoid valve

51

Valve relay system

Short circuit or ON failure

P.35B-58

52

Valve relay system

Open circuit or OFF failure

P.35B-62

53

Pump motor

• Seizure of the pump

motor*

• Abnormality at the

current detection circuit
of the M-ASTC-ECU

Refer to GROUP 35A,
HBB Trouble Code
Diagnosis

P.35A-23

.

54

Motor relay

Open circuit, short circuit or
failure of the motor relay
coil

Refer to GROUP 35A,
HBB Trouble Code
Diagnosis

P.35A-31

.

55

Pump motor circuit

Pump motor energized
abnormally for long period*

Refer to GROUP 35A,
HBB Trouble Code
Diagnosis

P.35A-56

.

56

Pressure switch

Open circuit or short circuit Refer to GROUP 35A,

HBB Trouble Code
Diagnosis

P.35A-69

.

57

Accumulator

Accumulator low-pressure
abnormality*

Refer to GROUP 35A,
HBB Trouble Code
Diagnosis

P.35A-77

.

58

M-ASTC-ECU (Power supply
drive circuit)

Pump motor drive circuit in
the M-ASTC-ECU
abnormality

Replace the M-ASTC-ECU
(Refer to GROUP 35C, M-
ASTC-ECU

P.35C-205

).

61

Master cylinder pressure sensor system

P.35B-71

62

G-sensor system

Open circuit or short circuit Refer to GROUP 35C,

Active skid control system
Trouble Code Diagnosis

P.35C-24

.

63

G-sensor system

Abnormal output signal

64

G-sensor system

G sensor seized

65

G-sensor system

Trouble in self-diagnosis

66

Steering wheel sensor system

Trouble in self-diagnosis

Refer to GROUP 35C,
Active skid control system
Trouble Code Diagnosis

P.35C-30

.

DIAGNOSTIC
TROUBLE
CODE NO.

INSPECTION ITEM

DIAGNOSTIC CONTENT

REFERENCE PAGE