Mitsubishi 380. Manual - part 425

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-240

STEP 2. Using diagnostic tool MB991958, check MPI data 
list item 13: TP Sensor.
(1) Connect diagnostic tool MB991958 to the data link 

connector.

(2) Turn the ignition switch to the "ON" position.
(3) Set diagnostic tool MB991958 to the data reading mode.

• Item 13: TP Sensor (MAIN).

• With the throttle valve in idle position, voltage should 

measure between 1100 and 1200 mV.

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

should measure 4,000 mV or more.

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage between 1100 and 1200 mV at 

idle, and 4,000 mV or more at the full-open position?
YES : Go to Step 3.
NO :  Check the TP sensor. Refer to GROUP13B <3.8L 

Engine>, Diagnostic Trouble Code Procedures 

13A-17

, DTCs P0122, P0123: TP Sensor System. 

Then check the symptom.

STEP 3. Using diagnostic tool MB991958, check data list.
(1) Connect diagnostic tool MB991958 to the data link 

connector.

(2) Start the engine.
(3) Set diagnostic tool MB991958 to the data reading mode for 

following items.

a. Item 12: Low-Reverse Solenoid Valve Duty (%)
b. Item 13: Underdrive Solenoid Valve Duty (%) 

c. Item 14: Second Solenoid Valve Duty (%) 

d. Item 15: Overdrive Solenoid Valve Duty (%) 
e. Item 16: Reduction Solenoid Valve Duty (%) 

• Check that the values shown below are displayed 

when each data list item is entered.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-241

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Are the solenoid valves operating properly?

YES : Go to Step 4.
NO :  Go to Step 6.

STEP 4. Adjust the line pressure.
Adjust the line pressure. Refer to 

P.23A-33

, Line Pressure 

Adjustment. 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-62

.

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. Replace each solenoid valve.
Replace the faulty solenoid valve with a new one.

Q: Is the symptom eliminated?

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

STEP 7. Replace the A/T-ECU.

Q: Is the symptom eliminated?

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

DRIVING CONDITION

DATA LIST ITEM

12

13

14

15

16

Driving at constant speed of 10 km/h in 1st gear

100%

0%

100%

100%

0%

Driving at constant speed of 30 km/h in 2nd gear

100%

0%

0%

100%

0%

Driving at constant speed of 50 km/h in 3rd gear

100%

0%

100%

0%

0%

Driving at constant speed of 50 km/h in 4th gear

0%

0%

100%

0%

100%

Driving at constant speed of 50 km/h in 5th gear

0%

100%

0%

0%

100%

VALVE BODY
ASSEMBLY

10DB117A

10DB123A

Underdrive
solenoid
valve

Second
solenoid
valve

Damper
control clutch
solenoid
valve

Overdrive
solenoid
valve

Low-reverse
solenoid
valve

Reduction (RED)
solenoid
valve

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-242

INSPECTION PROCEDURE 11: Early or Late Shifting in Some Gears

.

COMMENT

If some of the shift points are early or late when driv-
ing, the cause is probably a malfunction of the valve 
body, or it is due to the characteristics of the 
INVECS-II system but is not an abnormality.

.

TROUBLESHOOTING HINTS (The most 
likely causes for this condition:)

• Malfunction of the valve body

• Malfunction of the A/T-ECU system

Circuit drawings

• Refer to circuit diagrams GROUP-

90

• Refer to configuration diagrams GROUP-

80

• Refer to component locations GROUP-

70

DIAGNOSIS

Required Special Tool:

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

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A

STEP 1. Using diagnostic tool MB991958, check A/T 
Special Function test item 33: INVECS-II Control Stop.

CAUTION

To prevent damage to diagnostic tool MB991958, always 
turn the ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting diagnostic tool 
MB991958. 
(1) Connect diagnostic tool MB991958 to the data link 

connector.

(2) Start the engine.
(3) Set diagnostic tool MB991958 to the A/T special function  

test mode.

• Item 33: INVECS-II Control Stop.

• Drive the vehicle and confirm the gear shifting corre-

spond to the standard shift line of the shift pattern 
diagram. Refer to 

P.23A-3

.

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Does the gear shifting correspond to the standard shift 

line of the shift pattern diagram?
YES : The symptom is due to characteristics of the 

INVECS-II system, but is not abnormal.

NO :  Go to Step 2.

STEP 2. Check the shift points.

Q: Are the shift points early or late only when transmission 

fluid is 35

°C or less (early), or 125°C or more (late)?

YES : The symptom is due to characteristics of the 

INVECS-II system, but is not abnormal.

NO :  Go to Step 3.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-243

STEP 3. 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-62

.

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 :  Start over at Step 1.

VALVE BODY
ASSEMBLY

10DB117A