Mitsubishi Montero (2002-2004). Manual — part 876

TRANSFER DIAGNOSIS <ACTIVE TRAC 4WD II>

TSB Revision

AUTOMATIC TRANSMISSION DIAGNOSIS

23Ab-45

3. Read the diagnostic trouble codes by counting center

differential lock indicator light flashes.

4. Refer to

P.23Ab-47

, Diagnostic Trouble Codes Chart.

5. Erase the diagnostic trouble codes by the following

procedure.

(1) Turn the ignition switch to the "LOCK" (OFF) position.
(2) Disconnect the negative battery cable for 10 seconds or

more. Reconnect the cable.

(3) Turn the ignition switch to the "ON" position. Read the

diagnostic trouble code output and check that no
diagnostic trouble code is output.

(4) Start the engine and let it run until the engine has warmed

up. Run it at idle for approximately 10 minutes or longer.
The engine control module must build up the adaptive
memory for smooth idle and good performance.

UNDERSTANDING THE CENTER DIFFERENYIAL LOCK INDICATOR LIGHT FLASHES

NOTE: Other diagnostic trouble codes also are output by the flashing of the center differential lock indicator
light corresponding to the same code numbers as the scan tool displays.

INSPECTION USING SCAN TOOL MB991502,
DATA LIST

Required Special Tool:

• MB991502: Scan Tool (MUT-II)

AC204846AB

EXAMPLE OF FLASHING WHEN A DIAGNOSTIC
TROUBLE CODE IS SET

FLASHING WHEN NORMAL

ACX01947

FOR DIAGNOSTIC TROUBLE CODE No.23

AB

LIGHT
ON

LIGHT
OFF

PAUSE
TIME

TENS
SIGNAL

PLACE
DIVISION

UNITS
SIGNAL

1.5 s

0.5 s

0.5 s

ACX01929 AB

0.5 s

LIGHT
ON

LIGHT
OFF

TRANSFER DIAGNOSIS <ACTIVE TRAC 4WD II>

TSB Revision

AUTOMATIC TRANSMISSION DIAGNOSIS

23Ab-46

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 data link connector.
2. Turn the ignition switch to the "ON" position.
3. Carry out inspection by means of the Data List function. If

there is an abnormality, check and repair the chassis
harnesses and components. Refer to

P.23Ab-49

, Data List

Reference Table.

4. Re-check using scan tool MB991502 and confirm that the

abnormal input and output have returned to normal because
as a result of the repairs.

5. Check for and inspect any diagnostic trouble codes (DTCs)

that may have surfaced from testing. Erase the diagnostic
trouble codes (DTCs) when finished checking.

6. Turn the ignition switch to the "LOCK" (OFF) position.
7. Disconnect scan tool MB991502 from the data link

connector.

8. Start the engine again and do a test drive to confirm that the

problem is eliminated.

FAIL-SAFE/BACKUP FUNCTIONS

M1231111000047

When malfunctions of the main sensors or actuators
are detected by the transfer-ECU, the transfer is con-
trolled by pre-set control logic to maintain safe condi-
tions for driving.

The following table shows how the fail-safe/backup
function affects vehicle driveability and operation.

ACX01539AD

MB991502

16-PIN

MALFUNCTIONING ITEM

JUDGMENT CONDITION

CONTROL CONTENTS DURING
MALFUNCTION

Power supply voltage

Power supply voltage is 9.5 V and less. Control start prohibited
Power supply voltage is 18 V and over. Control stop

Main relay (inside of ECU)

Voltage at relay OFF is 6 V and over, or
voltage at relay ON is 6 V and less.

Control stop

Accelerator pedal position
sensor (APP)

APP voltage at idle condition is less
than 0.2 V.

Vehicle speed limitation

Front propeller shaft speed
sensor 1

Input signal from front propeller shaft
speed sensor is unstable during low
and medium speed driving. (When
malfunction is detected during 2WD

→

4WD shifting)

Control start prohibited

Front propeller shaft speed
sensor 2

Input signal from front propeller shaft
speed sensor is unstable at freewheel
engage switch ON condition. (When
malfunction is detected at 4WD
condition)

Control start prohibited

Rear propeller shaft speed
sensor 1

Input signal from rear propeller shaft
speed sensor is unstable when APP
voltage is 1.5 V and over. (When
malfunction is detected at 2WD and
4WD conditions)

Control start prohibited

TRANSFER DIAGNOSIS <ACTIVE TRAC 4WD II>

TSB Revision

AUTOMATIC TRANSMISSION DIAGNOSIS

23Ab-47

DIAGNOSTIC TROUBLE CODE CHART

M1231111100055

Rear propeller shaft speed
sensor 2

Input signal from rear propeller shaft
speed sensor is unstable when
freewheel engage switch is ON
condition. (When malfunction is
detected at 4WD condition)

Control start prohibited

Stoplight switch

Stoplight switch ON was detected for 15
minutes at vehicle speed of 15 km/h
and over.

Control continued

Transfer shift lever switch

Input signal from transfer shift lever
switch is unstable.

Control start prohibited

Transfer position switch 1

Shifting of transfer has not been
completed during driving.

Control prohibited

Transfer position switch 2

Input signals from detection switches
are unstable.

Control prohibited

Freewheel engage solenoid
valve

Energizing condition to solenoid valve
and ECU terminal voltage do not
accord.

Control start prohibited

Freewheel engage switch

Energizing condition to solenoid valve
and freewheel engage switch condition
do not accord.

Control prohibited

Shift actuator abnormality

ECU terminal voltage is more than main
relay voltage (90% of specified voltage)
or lower than main relay voltage (10%
of specified voltage).

Control stop

Shift actuator short-circuited

Actual value of actuator current is more
than target value +1A.

Control stop

Shift actuator open-circuited

Main relay voltage is 6V and over or
actual value of actuator current is less
than 0.1 A.

Control stop

Shift actuator overload

Accumulation time to drive actuator
exceeds 5 minutes.

Control stop

Dissimilar tire diameter

Speed difference between front wheel
and rear wheel at 4WD condition is
larger than set value.

Vehicle speed limitation

M-ASTC-ECU malfunction

Open circuit in all signal lies with the M-
ASTC-ECU

Control continued

Transfer-ECU malfunction

Malfunction of ECU was detected.

Control stop

MALFUNCTIONING ITEM

JUDGMENT CONDITION

CONTROL CONTENTS DURING
MALFUNCTION

CODE

DIAGNOSIS ITEM

REFERENCE PAGE

11

Power supply voltage system

Low voltage

P.23Ac-262

12

Over voltage

P.23Ac-262

13

Main relay system (inside of ECU)

Relay malfunction

P.23Ac-268

21

Accelerator pedal position sensor (APP) system Open-circuit/sensor

malfunction

P.23Ac-269

TRANSFER DIAGNOSIS <ACTIVE TRAC 4WD II>

TSB Revision

AUTOMATIC TRANSMISSION DIAGNOSIS

23Ab-48

22

Front propeller shaft speed sensor system

Open-circuit/short-
circuit/sensor
malfunction

P.23Ac-275

23

P.23Ac-275

24

Rear propeller shaft speed sensor system

Open-circuit/short-
circuit/sensor
malfunction

P.23Ac-287

25

P.23Ac-287

26

Stoplight switch system

Open-circuit/short-
circuit/lamp failure/
switch failure

P.23Ac-299

31

Transfer shift lever switch system

Open-circuit/short-
circuit/switch failure

P.23Ac-307

32

Transfer position switch system

Transfer shift
mechanism
malfunction/actuator
malfunction

P.23Ac-315

33

Transfer position switch system

Open-circuit/short-
circuit/switch failure

P.23Ac-315

34

Free-wheel engage solenoid valve system

Open-circuit/short-
circuit/solenoid valve
malfunction

P.23Ac-326

35

Free-wheel engage switch system

Open-circuit/short-
circuit/switch failure

P.23Ac-338

41

Shift actuator system (short-circuit, open-circuit) Open-circuit/short-

circuit/actuator
malfunction/ECU
malfunction

P.23Ac-349

42

Shift actuator system (short-circuit)

Short-circuit/actuator
malfunction/ECU
malfunction

P.23Ac-355

43

Shift actuator system (open-circuit)

Open-circuit/actuator
malfunction/ECU
malfunction

P.23Ac-355

44

Shift actuator system (Overload)

Transfer shift
mechanism
malfunction/actuator
malfunction

P.23Ac-361

45

Dissimilar tire diameter

Incorrect tire
pressure/dissimilar
tire size

P.23Ac-367

51

Transfer-ECU malfunction

Replace the transfer-
ECU

61

M-ASTC-ECU malfunction

Open-circuit/short-
circuit/ECU
malfunction

P.23Ac-368

CODE

DIAGNOSIS ITEM

REFERENCE PAGE