Mitsubishi Galant. Manual — part 443

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

23A-239

INSPECTION PROCEDURE 12: No Diagnostic Trouble Codes (Does not Shift)

AC004621

Backup Power Supply System Circuit

AB

AC004308AB

CONNECTOR: C-17

AC004197

PCM

AD

CONNECTOR: C-40

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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CIRCUIT OPERATION
PCM (terminal number 66) receives battery positive
voltage from the battery.

COMMENT
If shifting does not occur while driving and no
diagnostic trouble codes are output, a malfunction of
the Park/Neutral position switch, or PCM may exist.

TROUBLESHOOTING HINTS (The most likely

causes for this case:)

•

Malfunction of the A/T control relay

•

Malfunction of the Park/Neutral position switch

•

Damaged harness, connector

•

Malfunction of the PCM

DIAGNOSIS

Required Special Tool:
MB991502: Scan Tool (MUT-II)

STEP 1. Check the vehicle acceleration.

Q: Does the vehicle accelerate poorly (transaxle stays in

3rd gear) when starting from a stop with the selector
lever in "D" range?
YES : Go to Step 2.
NO : Go to Step 5.

AC004344

CONNECTOR: C-66

CONNECTOR
BLOCK (LH)

C-66

AB

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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STEP 2. Check the backup power supply voltage at PCM
connector C-40 by backprobing.
(1) Do not disconnect connector C-40.

(2) Measure the voltage between terminal 66 and ground by

backprobing.

•

Voltage should be battery positive voltage.

Q: Is the voltage normal?

YES : Go to Step 4.
NO : Go to Step 3.

STEP 3. Check connector C-40 at PCM for damage.
Q: Is the connector in good condition?

YES : Repair it because of harness open circuit between

PCM connector C-40 terminal 66 and battery.

NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

. Then check for the

symptom.

AC004197

PCM

AD

CONNECTOR: C-40

AC002091

C-40 CONNECTOR
HARNESS SIDE VIEW

AE

AC004197

PCM

AD

CONNECTOR: C-40

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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STEP 4. Using scan tool MB991502, read the A/T
diagnostic trouble code.

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to "LOCK" (OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Turn the ignition switch to "ON" position.
(3) Read the A/T diagnostic trouble code.
(4) Turn the ignition switch to "LOCK" (OFF) position.

Q: Is the A/T diagnostic trouble code number "54" output?

YES : Refer to

P.23A-208

, code number 54: A/T control

relay system.

NO : Go to Step 5.

STEP 5. Using scan tool MB991502, check data list item 61:
Park/Neutral Position Switch.
(1) Connect scan tool MB991502 to the data link connector.
(2) Turn the ignition switch to "ON" position.
(3) Set scan tool MB991502 to data reading mode for item 61:

Park/Neutral Position Switch.

•

Move the selector lever to "P," "R," "N," "D," "3," "2," "L"
positions to confirm whether the MUT-II.

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

Q: Is the switch operating properly?

YES : Check for the symptom. If the symptom is not

eliminated, replace the PCM.

NO : Refer to

P.23A-124

,

P.23A-143

, code number 27, 28:

Park/Neutral position switch system.

INSPECTION PROCEDURE 13: Poor Acceleration

COMMENT
If acceleration is poor when downshifting occurs
while driving, a malfunction of the engine system or a
brake or clutch may exist.

TROUBLESHOOTING HINTS (The most likely

causes for this case:)

•

Malfunction of the engine system

•

Malfunction of the each clutch system and each
brake system

•

Abnormal line pressure

•

Malfunction of the PCM

AC003081AC

MB991502

DATA LINK
CONNECTOR

AC003081AC

MB991502

DATA LINK
CONNECTOR