Mitsubishi Galant. Manual — part 445

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-247

INSPECTION PROCEDURE 15: Vehicle Shifts Differently with A/C Engaged

AC004622

Dual Pressure Switch System Circuit

AB

AC004375AB

CONNECTOR: A-34

AC004287

CONNECTOR: C-04, C-05

AG

C-04

C-05

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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CIRCUIT OPERATION

•

When the A/C is turned ON and the dual
pressure switch is closed, PCM (terminal number
83) receives battery voltage and then determines
the A/C compressor has been signaled to
engage.

•

When the A/C compressor is engaged, the PCM
increases line pressure and shift points to
compensate for the additional engine load.

COMMENT
The cause is probably a faulty dual pressure switch
circuit or a defective PCM.

TROUBLESHOOTING HINTS (The most likely

causes for this code to be set:)

•

Malfunction of the dual pressure switch

•

Damaged harness, connector

•

Malfunction of A/C system

•

Malfunction of the PCM

DIAGNOSIS

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

STEP 1. Using scan tool MB991502, check data list item 65:
Dual Pressure Switch.

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) Start the engine and run at idle.
(3) Set scan tool MB991502 to data reading mode for item 65:

Dual Pressure Switch.

•

When the A/C is in operation, the scan tool display
should be "ON."

•

When the A/C is not in operation, the scan tool display
should be "OFF."

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

Q: Is the switch operating properly?

YES : This malfunction is intermittent. Refer to GROUP 00,

How to Use Troubleshooting/Inspection Service
Points

−

How to Cope with Intermittent Malfunction

P.00-8

.

NO : Go to Step 2.

AC004376

CONNECTOR: C-12, C-15

AB

C-12

C-15

AC004197

PCM

AC

CONNECTOR: C-41

AC003081AC

MB991502

DATA LINK
CONNECTOR

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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STEP 2. Check connector A-34 at dual pressure switch for
damage.
Q: Is the connector in good condition?

YES : Go to Step 3.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

.

STEP 3. Check the power supply voltage at dual pressure
switch connector A-34.
(1) Disconnect the connector A-34 and measure at the harness

side.

(2) Start the engine and run at idle.

(3) Measure the voltage between terminal 1 and ground.

•

Voltage should be battery positive voltage.

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

Q: Is the voltage normal?

YES : Go to Step 9.
NO : Go to Step 4.

AC004375AB

CONNECTOR: A-34

AC004375AB

CONNECTOR: A-34

AC002094

HARNESS
CONNECTOR: A-34

AD

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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STEP 4. Check the power supply voltage at automatic
compressor controller connector C-15 by backprobing.
(1) Do not disconnect connector C-15.
(2) Start the engine and run at idle.
(3) Operate the A/C.

(4) Measure the voltage between terminal 4 and ground by

backprobing.

•

Voltage should be battery positive voltage.

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

Q: Is the voltage normal?

YES : Go to Step 8.
NO : Go to Step 5.

STEP 5. Check connectors C-15 at automatic compressor
controller and C-12 at intermediate connector for damage.
Q: Are the connectors in good condition?

YES : Go to Step 6.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

.

AC004376

CONNECTOR: C-15

AC

AC004378

C-15 CONNECTOR
HARNESS SIDE VIEW

AB

AC004376

CONNECTOR: C-12, C-15

AB

C-12

C-15