Mitsubishi 380. Manual — part 415

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-200

STEP 4. 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

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 6.

STEP 5. Replace the A/T-ECU.
(1) Replace the A/T-ECU.
(2) Test drive the vehicle.
(3) Check for A/T diagnostic trouble code.

Q: Were any A/T DTCs set?

YES : Go to Step 6.
NO : The procedure is complete.

STEP 6. Overhaul the A/T.
(1) Replace the following parts.

• If P0731, P0732 or P0733 are set individually or in a

group, replace the underdrive clutch. Refer to GROUP
23B, Underdrive Clutch and Input Shaft

23B-46

.

• If P0733 or P0734 are set individually or in a group,

replace the overdrive clutch. Refer to GROUP 23B,
Reverse and Overdrive Clutch

23B-48

.

• If P0736 is set, replace the reverse clutch. Refer to

GROUP 23B, Reverse and Overdrive Clutch

23B-48

.

• If P0731 or P0736 are set individually or in a group,

replace the low-reverse brake. Refer to GROUP 23B,
Transmission

23B-55

.

• If P0732 or P0734 are set individually or in a group,

replace the second brake. Refer to GROUP 23B,
Transmission

23B-56

.

• If P0731 is set, replace the one-way clutch. Refer to

GROUP 23B, Planetary Gear

23B-53

.

• If P0735 is set, check second brake, check overdrive

clutch and DIR clutch.

(2) Test drive the vehicle.
(3) Check for A/T diagnostic trouble code.

Q: Are any A/T DTCs set again?

YES : An A/T DTC may have set due to external radio

frequency interference (RFI) possibly caused by
cellular phone activity, or aftermarket components
installed on the vehicle.

NO : The procedure is complete.

VALVE BODY
ASSEMBLY

10DB117A

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-201

(P0741): Damper Clutch Control System

.

DTC SET CONDITIONS

Check Conditions

• Solenoid status: plunging into connecting condi-

tion.

• Transmission inhibitor switch position: D.

Judgement Criteria

• Time during 100% duty: 4 seconds or more.

.

OBD-II DRIVE CYCLE PATTERN

Start the engine, and drive at 100 km/h (62 mph) for
10 seconds. Then stop the vehicle, and turn OFF the
ignition switch. After that, restart the engine, and
drive again at 100 km/h (62 mph) for 10 seconds.

.

TROUBLESHOOTING HINTS (The most
likely causes for this code to be set are:)

• Malfunction of the damper clutch control solenoid

valve

• Malfunction of the input shaft speed sensor

• Malfunction of the valve body

• Damaged harness or connector

• Malfunction of the A/T-ECU

• Malfunction of the torque converter

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, read the A/T
diagnostic trouble code.

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) Turn the ignition switch to the "ON" position.
(3) Check for A/T diagnostic trouble code.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is (P0715) or (P0743) set?

YES <P0715 set> : Refer to

P.23A-55

, P0715: Input Shaft

Speed Sensor System.

YES <P0743 set> : Refer to

P.23A-185

, P0743: Damper

Clutch Control Solenoid Valve System.

NO : Go to Step 2.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-202

STEP 2. Using diagnostic tool MB991958, check data list
item 17: Damper Clutch Control Solenoid Valve Duty%.

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. (Warming up engine)
(3) Set diagnostic tool MB991958 to the data reading mode.

• Item 17: Damper Clutch Control Solenoid Valve Duty%.

• When driving at constant speed of 50 km/h, the dis-

play should be "70

− 90%" (Gear range: 3rd gear).

• When the accelerator pedal is released [at less than

50 km/h], the display should be "70

− 90% → 0%"

(decreases gradually as the vehicle speed
decreases) (Gear range: 3rd gear).

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

Q: Is the solenoid valve operating properly?

YES : Go to Step 3.
NO : Go to Step 5.

STEP 3. Using diagnostic tool MB991958, check data list
item 10: Damper Clutch Control Amount of Slippage.

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. (Warming up engine)
(3) Set diagnostic tool MB991958 to the data reading mode.

• Item 10: Damper Clutch Control Amount of Slippage.

• Driving at a constant speed of 50 km/h, the display

should be "100 to 300 r/min."

• Driving at a constant speed of 70 km/h, the display

should be "0 to 10 r/min."

• If the accelerator pedal is released, the display on

the diagnostic tool changes (50 km/h and less).

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

Q: Is the clutch operating properly?

YES : Go to Step 4.
NO : Go to Step 5.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-203

STEP 4. Using diagnostic tool MB991958, read the A/T
diagnostic trouble code.

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) Turn the ignition switch to the "ON" position.
(3) Check for A/T diagnostic trouble code.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is Item 10 set?

YES : Replace the A/T-ECU.
NO : The procedure is complete.

STEP 5. Check the hydraulic pressure (for torque
converter).
Measure the hydraulic pressure for torque converter. Check if
the hydraulic pressure is within the standard value. Refer to

P.23A-26

, Hydraulic Pressure Test.

Q: Is the hydraulic pressure within the standard value?

YES : Go to Step 7.
NO : Go to Step 6.

STEP 6. Adjust line pressure.
Adjust line pressure. Refer to

P.23A-33

, Line Pressure Adjust-

ment. Then check the symptom.

Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 8.

STEP 7. Replace the A/T-ECU.

Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 8.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827