Mitsubishi Galant (2004+). Manual - part 680

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-271

• 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 data list item 54: 
A/T Control Relay Output Voltage.

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 data reading mode.

• Item 54: A/T Control Relay Output Voltage.

• The voltage should equal battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage equal battery positive voltage?

YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunction 

P.00-6

.

NO :  Go to Step 2.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

23A-272

STEP 2. Check the A/T control relay.

(1) Remove the A/T control relay from the engine component 

relay box connector B-16X.

(2) Using jumper wires, connect terminal 2 to the positive 

battery terminal, and terminal 3 to the negative battery 
terminal.

(3) Measure the resistance between terminals 1 and 4 of the 

A/T control relay.

• The resistance should be measured less than 2 ohms.

• Disconnect the jumper wires. The resistance between 

terminals 1 and 4 should measure over limits (open cir-
cuit).

Q: Is the measured resistance less than 2 ohms when the 

relay is energized, and open circuit when the relay is 
de-energized?
YES : Go to Step 3.
NO :  Replace the A/T control relay.

STEP 3. Check A/T control relay socket B-16X in the 
engine compartment relay box for loose, corroded or 
damaged terminals, or terminals pushed back in the 
socket.

Q: Is the relay connector in good condition?

YES : Go to Step 4.
NO :  Repair or replace the damaged components. Refer to 

GROUP 00E, Harness Connector Inspection 

P.00E-2

.

AC306354

RELAY BOX

AB

CONNECTOR: B-16X

2

1

3

4

FRONT OF
VEHICLE

AC210725

2

1

3

4

AD

B-16X HARNESS CONNECTOR:
A/T CONTROL RELAY SIDE

FRONT OF VEHICLE

AC306354

RELAY BOX

AB

CONNECTOR: B-16X

2

1

3

4

FRONT OF
VEHICLE

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

23A-273

STEP 4. Measure the supply voltage at A/T control relay 
connector B-16X in the engine component relay box.

(1) Disconnect the A/T control relay.

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

• The measured voltage should equal battery positive 

voltage.

Q: Is the measured voltage equal to battery positive 

voltage?
YES : Go to Step 7.
NO :  Go to Step 5.

STEP 5. Check intermediate connector A-13 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.

Q: Are the connector and terminals in good condition?

YES : Go to Step 6.
NO :  Repair or replace the damaged components. Refer to 

GROUP 00E, Harness Connector Inspection 

P.00E-2

.

STEP 6. Check the harness for open circuit or short circuit 
to ground between A/T control relay connector B-16X 
terminal 1 in the engine component relay box and battery.

Q: Is the harness wire in good condition?

YES : Go to Step 15.
NO :  Repair or replace the harness wire.

AC306354

RELAY BOX

AB

CONNECTOR: B-16X

2

1

3

4

FRONT OF
VEHICLE

AC210728

1

3

2

4

AC

B-16X HARNESS 
CONNECTOR: 
RELAY BOX SIDE

FRONT OF 
VEHICLE

AC306223

A-13 (GR)

AB

CONNECTOR: A-13

1

4

7

8

2 3

5

13

14

17

15

12

16

11

10

9

6

AC306354

RELAY BOX

AB

CONNECTOR: B-16X

2

1

3

4

FRONT OF
VEHICLE

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

23A-274

STEP 7. Measure the supply voltage at A/T control relay 
connector B-16X in the engine component relay box.

(1) Disconnect the A/T control relay.
(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 2 and ground.

• The measured voltage should equal battery positive 

voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage equal to battery positive 

voltage?
YES : Go to Step 10.
NO :  Go to Step 8.

AC306354

RELAY BOX

AB

CONNECTOR: B-16X

2

1

3

4

FRONT OF
VEHICLE

AC210734

1

3

2

4

AC

B-16X HARNESS 
CONNECTOR: 
RELAY BOX SIDE

FRONT OF 
VEHICLE