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Mitsubishi 380. Manual - part 369

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-16

HOW TO PERFORM ACTUATOR TEST

Required Special Tools:

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

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A

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. Select "Interactive Diagnosis" from the start-up screen.

4. Select "System select."

5. Choose "ELC-A/T" from the "POWER TRAIN" tab.

6. Select "MITSUBISHI."

7. Select "Actuator Test."

8. Choose an appropriate item and select the "OK" button.

HOW TO DIAGNOSE THE CAN BUS LINES

Required Special Tools:

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

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-17

CAUTION

connector.

2. Turn the ignition switch to the "ON" position.

3. Select "CAN bus diagnosis" from the start-up screen.

4. When the vehicle information is displayed, confirm that it

matches the vehicle whose CAN bus lines will be
diagnosed.

• If they match, go to step 8.

• If not, go to step 5.

5. Select the "view vehicle information" button.

6. Enter the vehicle information and select the "OK" button.

7. When the vehicle information is displayed, confirm again

that it matches the vehicle whose CAN bus lines will be
diagnosed.

• If they match, go to step 8.

• If not, go to step 5.

8. Select the "OK" button.

9. When the optional equipment screen is displayed, choose

the one which the vehicle is fitted with, and then select the
"OK" button.

HOW TO INITIALIZE A/T LEARNING VALUE

M1231022600121

AIM

The use of EEPROM has enabled the A/T learned
value to be retained even after the battery terminals
are disconnected. However, the learned value should
be initialized if the A/T assembly, the engine assem-
bly, the valve body assembly or the solenoid valves
are replaced. The initialization procedure is as
below:

INITIALIZATION PROCEDURE

1. Shift the selector lever to the P range and turn the

ignition switch to the LOCK (OFF) position. Then,
connect the MUT-III to the diagnosis connector.

2. Initialize the learned value on the initialization

screen.

3. After this initialization, make the system learn the

idling in accordance with "Learning procedure for
idling in MPI engine" (Refer to GROUP 00

−

Precautions before Service

00-22

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-18

FAIL-SAFE/BACKUP FUNCTION

M1231008300234

When a malfunction of a main sensor or actuator is
detected by the A/T-ECU, the transmission is con-
trolled by pre-set control logic to maintain safe condi-
tions for driving.

The following table shows how the fail-safe/backup
function affects vehicle driveability and operation.

MALFUNCTIONING ITEM

JUDGEMENT
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 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, as a fail-safe.

Output shaft speed sensor

The output signal
from the output shaft
speed sensor is not
present for one
second or more
while the vehicle is
driven.

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 5 monitoring periods in
one drive cycle. When the judgment condition is
met, the A/T control relay is turned off. The
transmission will only operate in 3rd and reverse
gears until the system is repaired.

Underdrive solenoid valve

Second solenoid valve

Overdrive solenoid valve

Reduction (RED) solenoid valve

Damper control clutch (DCC)
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
shifting has been
completed.

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 A/T-ECU

Malfunction has
occurred in the
A/T-ECU.

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

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-19

ROAD TEST

M1231007800407

Check using the following procedures.

STEP

CONDITION
BEFORE
TEST/OPERATION

TEST/OPERATION

STANDARD

INSPECTION
ITEM

INSPECTION
PROCEDURE
PAGE

Ignition switch:
(LOCK) OFF

Ignition switch
(1) ON

Data list No.8

(1) Control Relay

Voltage [V]

A/T Control
relay
output
voltage

A/T Control
relay system
(

P.23A-207

Ignition switch:
ON
Engine: Stopped
Transmission
range: P

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

Data list No.34
(1) P, (2) R, (3) N, (4)
D

Transmissi
on range
switch

Transmission
range switch
system
(

P.23A-97

P.23A-119

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.27
(1) OFF, (2) ON, (3)
ON, (4) ON
Data list No.28
(1) OFF, (2) OFF, (3)
ON, (4) OFF
Data list No.29
(1) OFF, (2) OFF, (3)
OFF, (4) ON

Select
switch and
Shift switch

Shift switch
assembly
system
(

P.23A-252

Brake pedal
(1) Depressed
(2) Released

Data list No.19
(1) ON
(2) OFF

Stoplamp
switch

Stoplamp
switch system
(

P.23A-89

Ignition switch:
ST
Engine: Stopped

Cranking test with
lever in P or N range

Cranking should be
possible