Mitsubishi Galant (2004+). Manual - part 684

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-287

STEP 4. 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-79

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. Check the underdrive clutch.
(1) Remove the transaxle assembly.

(2) Check the facing for seizure and the piston seal ring for

damage and interference with the retainer. Repair or

replace the faulty parts. Refer to GROUP 23B, Underdrive
Clutch and Input Shaft

P.23B-60

. Then check the symptom.

Q: Is the symptom eliminated?

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

STEP 6. Replace the PCM.
Q: Is the symptom eliminated?

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

INSPECTION PROCEDURE 3: Does not Move Backward

COMMENT
If the vehicle does not move backward when the
selector lever is shifted from "N" to "R" range while
the engine is idling, the cause is probably abnormal
pressure or a malfunction of the reverse clutch,
low-reverse brake, or valve body.

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

• Abnormal reverse clutch pressure

• Abnormal low-reverse brake pressure

• Malfunction of the low-reverse solenoid valve

• Malfunction of the reverse clutch

• Malfunction of the low-reverse brake

• Malfunction of the valve body

• Malfunction of the PCM

AC001860 AB

VALVE
BODY
ASSEMBLY

AC001861

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-288

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 01: Low-Reverse 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 01: Low-Reverse Solenoid Valve.

• An audible clicking or buzzing should be heard when

the low-reverse 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 low-reverse solenoid valve.

Refer to GROUP 23B, Valve Body

P.23B-79

. Then

confirm that the symptom is eliminated.

STEP 2. Check the hydraulic pressure (for reverse clutch).

Measure the hydraulic pressure for the reverse clutch when the
selector lever is at the "R" range, and check if the hydraulic
pressure is within the standard value. Refer to

P.23A-29

Hydraulic Pressure Test.
Q: Is the hydraulic pressure within the standard value?

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

STEP 3. Check the hydraulic pressure (for low-reverse
brake).

Measure the hydraulic pressure for the low-reverse brake when
the selector lever is at the "R" range, and check if the hydraulic
pressure is within the standard value. Refer to

P.23A-29

Hydraulic Pressure Test.
Q: Is the hydraulic pressure within the standard value?

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

AC206894

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-289

STEP 4. Check the reverse clutch system and low-reverse

brake system.
(1) Remove the valve body cover and valve body. Refer to

P.23A-392

<F4A4B> or

P.23A-400

<F4A5A>, Transaxle

Assembly and GROUP 23B, Transaxle

P.23B-10

(2) Blow 108 kPa (15psi) compressed air into the reverse

clutch oil orifice of the transaxle case. Then check if the
reverse clutch piston moves and air pressures are
maintained in that condition. Repeat for the low-reverse
brake.

Q: Are the reverse clutch, low-reverse brake or both air

pressures maintained?
YES : Go to Step 5.
NO : Go to Step 6.

STEP 5. 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-79

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. Check the reverse clutch, low-reverse brake or
both. Remove the transaxle.

Check the facing for seizure and the piston seal ring for dam-
age and interference with the retainer. Repair or replace the
faulty parts. Refer to GROUP 23B, Transaxle

P.23B-10

Reverse and Overdrive Clutch

P.23B-62

. Then check the

symptom.
Q: Is the symptom eliminated?

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

STEP 7. Replace the PCM.
Q: Is the symptom eliminated?

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

AC001862

REVERSE CLUTCH
OIL ORIFICE

LOW-REVERSE
BRAKE OIL ORIFICE

AC001860 AB

VALVE
BODY
ASSEMBLY

AC001863 AB

LOW-REVERSE BRAKE

REVERSE CLUTCH

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
powertrain, 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
transaxle is in 1st, 2nd or reverse. Check if each hydraulic
pressure is within the standard value. Refer to

P.23A-29

Hydraulic Pressure 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-79

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