Mitsubishi Montero (2002-2004). Manual — part 866

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION DIAGNOSIS

23Ab-5

INSPECTION USING SCAN TOOL MB991502,
ROAD TEST AND DATA LIST

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 data link connector.
2. Turn the ignition switch to the "ON" position.
3. Carry out the inspection by means of the Road Test and the

Data List function. If there is an abnormality, check and
repair the chassis harnesses and components. Refer to

P.23Ab-7

, Road Test. Refer to

P.23Ab-33

, 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 after 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 FUNCTION

M1231101100106

When a malfunction of a main sensor or actuator is
detected by the PCM, the transmission is controlled
by pre-set control logic to maintain safe conditions
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 DEFAULT DURING MALFUNCTION

Input shaft speed sensor

If no output pulse from the
input shaft speed sensor is
detected for one second or
more when the vehicle
speed is 30 km/h (19 mph)
or greater.

The diagnostic trouble code is recorded when the
malfunction occurs once during 4 monitoring
periods in one drive cycle. When the judgment
condition is met, the transmission holds 3rd gear
or 2nd gear, depending on speed and "N" range
light flashes as a fail-safe.

Output shaft speed sensor Output from the output

shaft speed sensor is
continuously 50 % or less
of the output from the
vehicle speed sensor one
second or more when the
vehicle speed is 30 km/h
(19 mph) or more.

The diagnostic trouble code is recorded when the
malfunction occurs once during 4 monitoring
periods in one drive cycle. When the judgment
condition is met, the transmission holds 3rd gear
or 2nd gear, depending on speed and "N" range
light flashes as a fail-safe.

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION DIAGNOSIS

23Ab-6

Low-reverse solenoid
valve

Solenoid valve resistance
is below 2.7 ohms for 0.32
seconds.

The diagnostic trouble code is recorded when the
malfunction occurs during 4 monitoring periods in
one drive cycle. When the judgment condition is
met, the A/T control relay is turned off and "N"
range light flashes.

Underdrive solenoid valve
Second solenoid valve
Overdrive solenoid valve
Reduction solenoid valve
Torque converter clutch
solenoid valve
Incomplete
shifting

1st

The gear ratio value from
the output shaft speed
sensor is not the same as
the output from the input
shaft speed sensor for one
second after has been
completed.

The diagnostic trouble code is recorded when the
malfunction occurs during 4 monitoring periods in
one drive cycle. When the judgment condition is
met, the A/T control relay is turned off and "N"
range light flashes.

2nd
3rd
4th
5th
Reverse

A/T control relay

A/T control relay voltage is
less than seven volts for
0.1 second after the ignition
switch is turned "ON."

The A/T control relay is switched off. The
transmission will only operate in 3rd and Reverse
gears until the system is repaired.

Malfunction in the PCM

Malfunction has occurred in
the PCM.

The A/T control relay is switched off. The
transmission will only operate in 3rd and Reverse
gears until the system is repaired.

MALFUNCTIONING ITEM JUDGMENT CONDITION

CONTROL DEFAULT DURING MALFUNCTION

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION DIAGNOSIS

23Ab-7

ROAD TEST

M1231100800135

Check using the following procedures

STEP CONDITION

BEFORE TEST/
OPERATION

TEST/
OPERATION

STANDARD

INSPECTION
ITEM

DTC

INSPECTION
PROCEDURE
PAGE

1

Ignition switch:
OFF

Ignition switch
(1) ON

Data list No. 54

(1) Control Relay

Voltage [V]

A/T Control
relay output
voltage

54

A/T Control
relay system
(

P.23Ac-237

)

2

Ignition switch:
ON
Engine: Stopped
Transmission
range: P

Transmission
range
(1) P, (2) R, (3)
N, (4) D

Data list No. 61
(1) P, (2) R, (3) N,
(4) D

Transmission
range switch

27, 28

Transmission
range switch
system
(

P.23Ac-93

,

P.23Ac-123

)

Transmission
range
(1) D (1st gear)
(2) Select the
sport mode (1st
gear)
(3) Upshift and
hold the selector
lever in that
position (2nd
gear)
(4) Downshift
and hold the
selector lever in
that position (1st
gear)

Data list No. 67
(1) OFF, (2) ON,
(3) ON, (4) ON
Data list No. 68
(1) OFF, (2) OFF,
(3) ON, (4) OFF
Data list No. 69
(1) OFF, (2) OFF,
(3) OFF, (4) ON

Select switch
Shift switch

-

Shift switch
assembly
system
(

P.23Ad-48

)

Shift indicator light
(1) "D" and "1"
illuminates
(2) Only "1"
illuminates
(3) Only "2"
illuminates
(4) Only "1"
illuminates

Accelerator
pedal
(1) Fully closed
(2) Depressed
(3) Fully open

Data list No. 11
(1) 200

− 800 mV

(2) Gradually rises
from (1)
(3) 3,800

− 4,900

mV

Throttle
position sensor

−

−

Brake pedal
(1) Depressed
(2) Released

Data list No. 26
(1) ON
(2) OFF

Stoplight
switch

26

Stoplight switch
system
(

P.23Ac-83

)

Transfer position
(1) Other than
4LLc
(2) 4LLc

Data list No. 26
(1) OFF
(2) ON

4LLc detection
switch

−

4LLc detection
switch system
(

P.23Ad-67

)

3

Ignition switch:
ST
Engine: Stopped

Cranking test
with lever in P or
N range

Cranking should
be possible

Cranking

−

Engine does not
start (

P.23Ad-2

)

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION DIAGNOSIS

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4

Engine warmed

Drive for 15
minutes or more
so that the
transmission
fluid temperature
becomes 70

−

80

°C. (158 −

176

°F)

Data list No. 15
Gradually rises to
70

− 80°C (158 −

176

°F)

Transmission
fluid
temperature
sensor

15, 16

Transmission
fluid
temperature
sensor system
(

P.23Ac-2

,

P.23Ac-18

)

STEP CONDITION

BEFORE TEST/
OPERATION

TEST/
OPERATION

STANDARD

INSPECTION
ITEM

DTC

INSPECTION
PROCEDURE
PAGE