Mitsubishi Montero (2004+). Manual — part 937

AUTOMATIC TRANSMISSION DIAGNOSIS

TSB Revision

AUTOMATIC TRANSMISSION

23A-323

DIAGNOSIS

Required Special Tool:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

STEP 1. Using scan tool MB991958, check actuator test.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991958 to the actuator test mode for

following items.

a. Item 01: Low-reverse solenoid valve
b. Item 02: Underdrive solenoid valve

c. Item 03: Second solenoid valve

d. Item 04: Overdrive solenoid valve
e. Item 05: Reduction solenoid valve

• An audible clicking or buzzing should be heard when

the solenoid valves are energized.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are the solenoid valves operating properly?

YES : Go to Step 2.
NO : Repair or replace the solenoid valves. Refer to

GROUP 23B, Valve Body

P.23B-63

. Then confirm

that the symptom is eliminated.

STEP 2. Check the hydraulic pressure.
(1) Measure the hydraulic pressure of each element. Check if

each hydraulic pressure is within the standard value. Refer
to

P.23A-26

, Hydraulic Pressure Test.

(2) If some elements pressure are within the standard value

and some are not, recheck the symptom.

Q: Are all hydraulic pressures within the standard value?

YES : Go to Step 6.
NO : Go to Step 3.

STEP 3. Adjust the line pressure.
Adjust the line pressure. Refer to

P.23A-41

, Line Pressure

Adjustment. Then check the symptom.
Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 4.

AC307591 AC

MB991911

MB991824

MB991827

AC307591

DATA LINK

CONNECTOR

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

23A-324

STEP 4. Replace the transmission oil pump.
(1) Remove the transmission.
(2) Replace the transmission oil pump. (Oil pump can not be

repaired). Refer to GROUP 23B, Transmission

P.23B-14

.

Then check the symptom.

Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 5.

STEP 5. Disassemble and clean the valve body.
Check the O-ring installation bolts for looseness and the valve
body for damage. Repair or replace the faulty parts. Refer to
GROUP 23B, Valve Body

P.23B-63

.

Replace the valve body assembly if the damages are thought
to be irreparable. Then check the symptom.
Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 7.

STEP 6. Check each brake and clutch.
(1) Remove the transmission.
(2) Check the facing for seizure and piston seal ring for

damage and interference with retainer. Repair or replace
the faulty parts. Refer to GROUP 23B, Transmission

P.23B-14

, Underdrive Clutch

P.23B-59

, Reverse and

Overdrive Clutches

P.23B-50

, Direct Clutch

P.23B-71

.

Then check for the symptom.

Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 7.

STEP 7. Replace the PCM.
Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Start over at Step 1.

AC204883 AD

ACX02161AD

VALVE BODY ASSEMBLY

AC204883 AH

OVERDRIVE
CLUTCH

REDUCTION
BRAKE

REVERSE
CLUTCH

SECOND
BRAKE

LOW-REVERSE
BRAKE

UNDERDRIVE
CLUTCH

DIRECT
CLUTCH

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

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INSPECTION PROCEDURE 10: Early or Late Shifting All Gears

.

COMMENT
If all shift points are early or late while driving, the
cause is probably a malfunction of the output shaft
speed sensor, TP sensor or a solenoid valve.

.

TROUBLESHOOTING HINTS (THE MOST LIKELY
CAUSES FOR THIS CASE:)

• Malfunction of the output shaft speed sensor

• Malfunction of the TP sensor

• Malfunction of each solenoid valve

• Abnormal line pressure

• Malfunction of the valve body

• Malfunction of the PCM

DIAGNOSIS

Required Special Tool:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

STEP 1. Using scan tool MB991958, check data list item 23:
Output Shaft Speed Sensor.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Start the engine.
(3) Set scan tool MB991958 to the data reading mode.

• Item 23: Output Shaft Speed Sensor.

• When driving at constant speed of 50 km/h (31

mph), the display should be "1,400

− 1,700 r/min"

(Gear range: 4th gear).

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : Go to Step 2.
NO : Refer to

P.23A-91

, DTC 23: Output shaft speed

sensor system.

AC307591 AC

MB991911

MB991824

MB991827

AC307591

DATA LINK

CONNECTOR

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

23A-326

STEP 2. Using scan tool MB991958, check data list item 11:
TP Sensor.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991958 to the data reading mode.

• Item 11: TP Sensor.

• With the throttle valve in the idle position, voltage

should measure between 200 and 800 mV.

• With the throttle valve in the full-open position, volt-

age should measure between 3,800 and 4,900 mV.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 200 and 800 mV at

idle, and between 3,800 and 4,900 mV in the full-open
position?
YES : Go to Step 4.
NO : Go to Step 3.

STEP 3. Using scan tool MB991958, read the MFI
diagnostic trouble code.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Check for MFI diagnostic trouble code.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are MFI DTC Nos. of TP sensor system set?

YES : Refer to GROUP 13A, Diagnosis

− Diagnostic

Trouble Code Chart

P.13A-26

.

NO : Go to Step 8.

AC307591 AC

MB991911

MB991824

MB991827

AC307591

DATA LINK

CONNECTOR

AC307591 AC

MB991911

MB991824

MB991827

AC307591

DATA LINK

CONNECTOR