Mitsubishi 380. Manual - part 371

 

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Mitsubishi 380. Manual - part 371

 

 

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-24

3rd gear 
incorrect ratio 
(

P.23A-196

).

Does not 
shift from 3 
to 4 or 4 to 
3

Low-reverse 
solenoid valve 
system 
(

P.23A-133

).

Reduction 
solenoid valve 
system 
(

P.23A-154

).

3rd gear 
incorrect ratio 
(

P.23A-196

).

4th gear 
incorrect ratio 
(

P.23A-196

).

Does not 
shift from 4 
to 5 or 5 to 
4

Underdrive 
solenoid valve 
system(

23A-200

).

Second 
solenoid valve 
system 
(

P.23A-154

).

4th gear 
incorrect ratio 
(

P.23A-196

).

5th gear 
incorrect ratio 
(

P.23A-196

).

STEP

CONDITION 
BEFORE 
TEST/OPERATION

TEST/OPERATION

STANDARD

INSPECTION 
ITEM

INSPECTION 
PROCEDURE 
PAGE

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-25

TORQUE CONVERTER STALL TEST

M1231005400362

This test measures the maximum engine speed when the 
selector lever is in the "D" or "R" position and the torque con-
verter stalls. This tests the operation of the torque converter, 
starter motor and one-way clutch operation, as well as the hold-
ing performance of the clutches and brakes in the transmission.

WARNING

Do not let anyone stand in front of or behind the vehi-
cle while this test is performed.

1. Check the transmission fluid level and temperature. Check 

the engine coolant temperature.

• Transmission fluid level: At the "HOT" mark on the dipstick

• Transmission fluid temperature: 70 − 80°C

• Engine coolant temperature: 80 − 100°C

NOTE: Measures transmission fluid temperature with 
diagnostic tool MB991958 (MUT-III sub assembly).

2. Check both rear wheels.

3. Pull the parking brake lever on, with the brake pedal fully 

depressed.

4. Start the engine.

9

Transmission 
range: N (on a 
flat and straight 
road)

Monitor data list 
No.22 and No.23 
with the diagnostic 
tool MB991958 
(MUT-III sub 
assembly)
(1) Move selector 
lever to R range, 
drive at constant 
speed of 10 km/h

The ratio between 
data list No.22 and 
No.23 should be the 
same as the gear 
ratio when reversing.

Does not 
shift

Input shaft 
speed sensor 
system 
(

P.23A-55

).

Output shaft 
speed sensor 
system 
(

P.23A-72

).

Reverse gear 
incorrect ratio 
(

P.23A-196

).

STEP

CONDITION 
BEFORE 
TEST/OPERATION

TEST/OPERATION

STANDARD

INSPECTION 
ITEM

INSPECTION 
PROCEDURE 
PAGE

10DB148A

Reverse

clutch

Low-

reverse

brake

Under-

drive

clutch

Second

brake

Reverse

clutch

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-26

CAUTION

• The throttle should not be fully open for any more than 

five seconds.

• If you repeat the stall test when the transmission fluid 

temperature is greater than 80

°C, move the selector 

lever to the "N" position and let the engine run at 
approximately 1,000 r/min for at least one minute. Wait 
until the transmission fluid temperature returns to 80

°C  

or less.

5. Move the selector lever to the "D" position. Fully depress the 

accelerator pedal and read the maximum engine speed at 
this time.

Standard value: Stall speed: 2,100 

 2,600 r/min

6. Move the selector lever to the "R" position. Fully depress the 

accelerator pedal and read the maximum engine speed.

Standard value: Stall speed: 2,100 

 2,600 r/min

TORQUE CONVERTER STALL TEST JUDGMENT 
RESULTS

1. Stall speed is too high in both "D" and "R" range

• Malfunction of the torque converter (Slippage on the splines 

of the torque converter and the input shaft)

• Low line pressure

• Low-reverse brake slippage and malfunction of the one-way 

clutch

2. Stall speed is too high in "D" range only

• Underdrive clutch slippage

3. Stall speed is too high in "R" range only

• Reverse clutch slippage

4. Stall speed is too low in both "D" and "R" ranges

• Malfunction of the torque converter (Slippage of the 

one-way clutch)

• Insufficient engine output

HYDRAULIC PRESSURE TESTS

M1231005500392

CAUTION

The transmission fluid temperature should be between 70 
 80°C during the test.
1. Check the transmission fluid level and temperature. Check 

engine coolant temperature.

• Transmission fluid level: "HOT" mark on the dipstick

• Transmission fluid temperature: 70 − 80°C

• Engine coolant temperature: 80 − 100°C

2. Raise the vehicle so that the wheels are free to turn.

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-27

3. Connect the special tools (3.0 MPa (427 psi) oil pressure 

gauge [MD998330] and adapters [MD998332, MD998900]) 
to each pressure discharge port.

NOTE: 

.

• 2ND: Second brake pressure port

• UD: Underdrive clutch pressure port

• LR: Low-reverse brake pressure port

• DR: Torque converter release pressure port

• DA: Torque converter apply pressure port

• RV: Reverse clutch pressure port

• OD: Overdrive clutch pressure port

• DIR: Direct clutch pressure port

• RED: Reduction clutch pressure port

4. Restart the engine.

5. Check that there are no leaks around the special tool port 

adapters.

6. Measure the hydraulic pressure at each port under the 

conditions given in the standard hydraulic pressure table, 
and check that the measured values are within the standard 
value ranges.

7. If the pressure is not within the standard value, stop the 

engine and refer to the hydraulic pressure test diagnosis 
table.

8. Remove the O-ring from the port plug and replace it.

9. Remove the special tool, and install the plugs to the 

hydraulic pressure ports.

10.Start the engine and check that there are no leaks around 

the plugs.

AC006151AB

MD998900

MD998330

VALVE BODY
COVER

AC006150

<UNDER SIDE VIEW>

VALVE BODY COVER

MD998332

MD998330

AB

AC006149

MD998332

MD998330

VALVE BODY COVER

AB

10DB153A

MD998900

DIR

PORT

MD998330

TOPSIDE

10DB154A

MD998900

TOPSIDE

RED PORT

 

 

 

 

 

 

 

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