Mitsubishi Galant (2004+). Manual - part 679

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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DTC 54 (P1751): A/T Control Relay System

RELAY
BOX

JUNCTION
BLOCK

JOINT
CONNECTOR
(1)

IGNITION
SWITCH (IG1)

BATTERY

A/T CONTROL
RELAY

SOLENOID
VALVE POWER
SUPPLY 

RELAY
BOX

POWERTRAIN
CONTROL
MODULE

AC209761AC

A/T Control Relay System Circuit

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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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

AC306248AC

B-21 
(B)

CONNECTOR: B-21

PCM

AIR
CLEANER

73

80

54

67

60

71 72

77 78 79

64

51

59

58

65

52

66

53

75

74

76

81 82

83

63

JAE

62

68

61

55

69

56

70

57

AC305231

CONNECTOR: C-01

AS

33

22

11

28

17

16

15

14

13

12

25

2324

2627

3

1 2

4 5

21

20

19

18

29 30

32

31

7

6

8

10

9

AUTOMATIC TRANSAXLE DIAGNOSIS

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.

CIRCUIT OPERATION

• A/T control relay (terminal 1) receives the battery 

positive voltage through a dedicated 20 amp 
fuse.

• When the ignition switch is turned to the "ON" 

position, the PCM (terminal 82) receives battery 
voltage from the ignition switch. The PCM (termi-
nal 82) applies voltage to energize the A/T control 
relay (terminal 3). With the A/T control relay ener-
gized, system voltage is applied to the PCM (ter-
minals 70 and 57).

.

DESCRIPTIONS OF MONITOR METHODS

• If relay output voltage is below specified value, 

PCM judges that A/T control relay has a failure.

.

MONITOR EXECUTION

• Continuous

.

MONITOR EXECUTION CONDITIONS (Other 
monitor and Sensor)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• DTC 41 (P0731): 1st gear incorrect ratio

• DTC 42 (P0732): 2nd gear incorrect ratio

• DTC 43 (P0733): 3rd gear incorrect ratio

• DTC 44 (P0734): 4th gear incorrect ratio

• DTC 46 (P0736): Reverse gear incorrect ratio

• DTC 36 (P0743): Torque converter clutch sole-

noid malfunction

• DTC 31 (P0753): Low-reverse solenoid malfunc-

tion

• DTC 32 (P0758): Underdrive solenoid malfunc-

tion

• DTC 33 (P0763): Second solenoid malfunction

• DTC 34 (P0768): Overdrive solenoid malfunction

Sensor (The sensor below is determined to be 

normal)

• Torque converter clutch solenoid

• Low-reverse solenoid

• Underdrive solenoid

• Second solenoid

• Overdrive solenoid

.

AC207134

C-214

C-215

CONNECTORS: C-214, 215

AO

1

3 4

2

6

5

C-214

C-215

6

1

7

2

9

8

10

3

5

12

11

4

1314

AUTOMATIC TRANSAXLE DIAGNOSIS

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AUTOMATIC TRANSAXLE

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LOGIC FLOW CHARTS (Monitor Sequence)

.

DTC SET CONDITIONS

Check Conditions

• Voltage of battery: 9 volts or more.

• Time after PCM turns on A/T control relay: 0.5 

second or more.

Judgement Criteria

• A/T control relay output voltage: 7 volts or less. 

(0.1 second)

• If DTC 54 (P1751) is set consecutively four times, 

the transaxle is locked into 3rd gear as a fail-safe 
measure, and the "N" range light flashes once 
per second.

.

OBD-II DRIVE CYCLE PATTERN
Start the engine, and keep the vehicle stopped in "P" 
range for 5 seconds.

.

TROUBLESHOOTING HINTS (The most likely 
causes for this code to be set are:)

• Malfunction of the A/T control relay

• Damaged harness or connector

AC205241

START

END

No

Malfunction

Yes

Good

No

Yes

No

Yes

No

Yes

No

Yes

Timer start

TCM turn on A/T 
control relay

Timer > 0.5 sec.

Voltage of battery > 9 V

Output voltage from 
control relay < 7 V

Continuous failure 
for 0.1 sec.

PCM

AB