Mitsubishi Galant 9G. Manual — part 553

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-290

INSPECTION PROCEDURE 4: Does not Move (Forward or Backward)

.

COMMENT

If the vehicle does not move forward or backward
when the selector lever is shifted to any position
while the engine is idling, the cause is probably
abnormal line pressure, or a malfunction of the pow-
ertrain, oil pump or valve body.

.

TROUBLESHOOTING HINTS (THE MOST
LIKELY CAUSES FOR THIS CONDITION:)

• Abnormal line pressure

• Malfunction of the powertrain

• Malfunction of the oil pump

• Malfunction of the valve body

• Low transmission fluid level

• Malfunction of the PCM

DIAGNOSIS

STEP 1. Check the hydraulic pressure.
Measure the hydraulic pressure of each element when the tran-
saxle is in 1st, 2nd or reverse. Check if each hydraulic pressure
is within the standard value. Refer to

P.23A-29

, Hydraulic Pres-

sure Test. If some elements pressures are within the standard
value and some are not, recheck the symptom.
Q: Are all pressures within the standard value?

YES : Check transmission fluid level and condition. If not

OK, repair or replace as necessary, then retest the
system. If OK, go to Step 3.

NO : Go to Step 2.

STEP 2. Disassemble and clean the valve body.
Check the O-ring installation bolts for looseness and valve
body for damage. Repair or replace the faulty parts. Refer to
GROUP 23B, Valve Body

P.23B-80

.

Replace the valve body assembly if the damages are thought
to be irreparable. Then retest the symptom.
Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 4.

STEP 3. Check the transaxle powertrain components.
Disassemble the transaxle and check the planetary gear and
output shaft, etc. Repair or replace the damaged parts. Refer to
GROUP 23B, Transaxle

P.23B-10

, Planetary Gear

P.23B-69

,

Output Shaft

P.23B-73

, Differential

P.23B-76

. Then check the

symptom.
Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 5.

AC001860 AB

VALVE
BODY
ASSEMBLY

AC004468AB

PLANETARY GEAR

OUTPUT SHAFT

DIFFERENTIAL

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

23A-291

STEP 4. Check the oil pump.
(1) Remove the transaxle.
(2) Check the oil pump (incorrect installation, damage and etc.)

and replace the oil pump assembly if necessary (The oil
pump cannot be disassembly).Refer to GROUP 23B,
Transaxle

P.23B-10

. Confirm that the malfunction symptom

is eliminated.

Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 5.

STEP 5. Replace the PCM.
Q: Is the symptom eliminated?

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

INSPECTION PROCEDURE 5: Engine Stalls when Moving Selector Lever from "N" to "D" or "N" to "R"

.

COMMENT

If the engine stalls when the selector lever is shifted
from "N" to "D" or "R" range while the engine is idling,
the cause is probably a malfunction of the engine
system, torque converter clutch solenoid valve, valve
body or torque converter (torque converter clutch
malfunction).

.

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

• Malfunction of the engine system

• Malfunction of the torque converter clutch sole-

noid

• Malfunction of the valve body

• Malfunction of the torque converter (Malfunction

of the torque converter clutch)

• Malfunction of the PCM

DIAGNOSIS

STEP 1. Check the engine system.
Refer to GROUP 13A <2.4L Engine>, Diagnosis

− Trouble

Symptom Chart

− When the engine is hot, it stalls at idle

P.13A-38

.

Refer to GROUP 13B <3.8L Engine>, Diagnosis

− Trouble

Symptom Chart

− When the engine is hot, it stalls at idle

P.13B-38

.

Q: Is the inspection result good?

YES : Go to Step 2.
NO : Repair or replace the engine components.

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

23A-292

STEP 2. Replace the torque converter clutch solenoid
valve.
Replace the torque converter clutch solenoid valve. Refer to
GROUP 23B, Valve Body

P.23B-80

. Then check the symptom.

Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 3.

STEP 3. Disassemble and clean the valve body.
Check the O-ring installation bolts for looseness and valve
body for damage. Repair or replace the faulty parts. Refer to
GROUP 23B, Valve Body

P.23B-80

.

Replace the valve body assembly if the damages are thought
to be irreparable. Then check the symptom.
Q: Is the repair possible and the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 4.

STEP 4. Replace the torque converter assembly.
(1) Remove the transaxle.
(2) Replace the torque converter assembly. Refer to GROUP

23B, Transaxle

P.23B-10

. Then check the symptom.

Q: Is the symptom eliminated?

YES : The procedure is complete.
NO : Go to Step 5.

STEP 5. Replace the PCM.
Q: Is the symptom eliminated?

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

AC001866

AC001860 AB

VALVE
BODY
ASSEMBLY

AC001857

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

23A-293

INSPECTION PROCEDURE 6: Shift Shock when Shifting from "N" to "D" and Long Delay

.

COMMENT

If abnormal shock or delay of two seconds or more
occurs when the selector lever is shifted from "N" to
"D" range while the engine is idling, the cause is
probably abnormal underdrive clutch pressure or a
malfunction of the underdrive clutch, valve body or
TP sensor.

.

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

• Abnormal underdrive clutch pressure

• Malfunction of the underdrive solenoid valve

• Malfunction of the underdrive clutch

• Malfunction of the valve body

• Malfunction of the TP sensor

• Malfunction of the PCM

DIAGNOSIS

Required Special Tool:

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

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A

STEP 1. Using scan tool MB991958, check actuator test
item 02: Underdrive Solenoid Valve.

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) Set scan tool MB991958 to the actuator test mode.

• Item 02: Underdrive Solenoid Valve.

• An audible clicking or buzzing should be heard when

the underdrive solenoid valve is energized.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the solenoid valve operating properly?

YES : Go to Step 2.
NO : Repair or replace the underdrive solenoid valve.

Refer to GROUP 23B, Valve Body

P.23B-80

. Then

confirm that the symptom is eliminated.

STEP 2. Check when shift shock occurs.
Q: When does the shift shock occur?

When engaging from "N" to "D" : Go to Step 3.
When the vehicle starts moving : Go to Step 6.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827