Mitsubishi Galant (2004+). Manual — part 617

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-19

HOW TO DIAGNOSE THE CAN BUS LINES

Required Special Tools:

• MB991958: Scan 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 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. 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 matches, 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 matches, 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.

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

23A-20

FAIL-SAFE/BACKUP FUNCTION

M1231008300234

When a malfunction of a main sensor or actuator is
detected by the PCM, the transaxle is controlled by
pre-set control logic to maintain safe conditions 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 transaxle 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 4 monitoring periods in
one drive cycle. When the judgment condition is
met, the A/T control relay is turned off. The
transaxle will only operate in 3rd and reverse
gears until the system is repaired.

Underdrive solenoid valve
Second solenoid valve
Overdrive solenoid valve
Torque converter clutch 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
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 transaxle
will only operate in 3rd and reverse gears until the
system is repaired.

Malfunction in the PCM

Malfunction has
occurred in the
PCM.

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

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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ROAD TEST

M1231007800407

Check using the following procedures.

STEP CONDITION

BEFORE
TEST/OPERATION

TEST/OPERATION

STANDARD

INSPECTION
ITEM

DTC INSPECTION

PROCEDURE PAGE

Ignition switch:
(LOCK) OFF

Ignition switch
(1) ON

Data list No.54

(1) Control Relay

Voltage [V]

A/T Control
relay
output
voltage

A/T Control relay
system
(

P.23A-267

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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Ignition switch:
ON
Engine: Stopped
Transmission
range: P

Transmission range
<Vehicles without
sport mode>
(1) P, (2) R, (3) N, (4)
D, (5) 3, (6) 2, (7) L

Data list No.61
(1) P, (2) R, (3) N, (4)
D, (5) 3, (6) 2, (7) L

Transmissi
on range
switch

27,
28

Transmission
range switch
system
(

P.23A-121

P.23A-166

Transmission range
<Vehicles with sport
mode>
(1) P, (2) R, (3) N, (4)
D
Transmission range
<Vehicles with sport
mode>
(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)