Mitsubishi Galant 9G. Manual - part 1472

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-298

STEP 3. Check the SRS-ECU connector C-120, C-121 and 
C-122.
Q: Are connectors correctly engaged?

YES : Go to Step 4.
NO :  Engage the connectors correctly. Then go to Step 5.

AC307741

CONNECTORS: C-120, C-121, C-122

C-120 (Y),
C-121 (Y),
C-122 (Y)

AB

SRS-ECU

63

55

51

69

61

66

58

65

64

56 57

68

60

67

59

70

62

53

52 B

A

54

C-120 Harness side
connector (rear view)

C-121 Harness side
connector (rear view)

42

31

38

27

21

41

28

39

22

30

25

47

36

33

44

34

45

37

48

26

29

23

40

32

43

35

46

24

B

A

C-122 Harness side
connector (rear view)

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-299

STEP 4. Check SRS-ECU connector C-120, C-121 and 
C-122 for damage.
(1) Disconnect SRS-ECU connectors C-120, C-121 and C-122.
(2) Check the connector lock switch terminal inside the harness 

side connector for improper contact or deformation.

Q: Are the SRS-ECU connector C-120, C-121 and C-122 in 

good condition? 
YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1519 sets, 
replace the SRS-ECU (Refer to 

P.52B-365

). Then go 

to Step 5.

NO :  Replace the SRS-ECU connector C-120, C-121 and 

C-122. Refer to GROUP 00E, Harness Connector 
Inspection . Then go to Step 5.

AC307741

CONNECTORS: C-120, C-121, C-122

C-120 (Y),
C-121 (Y),
C-122 (Y)

AB

SRS-ECU

63

55

51

69

61

66

58

65

64

56 57

68

60

67

59

70

62

53

52 B

A

54

C-120 Harness side
connector (rear view)

C-121 Harness side
connector (rear view)

42

31

38

27

21

41

28

39

22

30

25

47

36

33

44

34

45

37

48

26

29

23

40

32

43

35

46

24

B

A

C-122 Harness side
connector (rear view)

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

AC307924 AB

SRS-ECU HARNESS SIDE 
CONNECTOR (FRONT VIEW)

CONNECTOR LOCK
SWITCH TERMINAL

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-300

STEP 5. Recheck for diagnostic trouble code. 
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC B1519 set?

YES : Return to Step 1.
NO :  The procedure is complete. 

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-301

DTC B1520: Seat belt switch (LH) malfunction DTC B1521: Seat belt switch (LH) circuit open (for 
Normal/Close terminal) DTC B1522: Seat belt switch (LH) circuit (ground side) shorted (for 
Normal/Close terminal) DTC B1523: Seat belt switch (LH) circuit (power supply side) shorted (for 
Normal/Close terminal) DTC B1524: Seat belt switch (LH) circuit open (for Normal/Open terminal) DTC 
B1525: Seat belt switch (LH) circuit (ground side) shorted (for Normal/Open terminal) DTC B1526: 
Seat belt switch (LH) circuit (power supply side) shorted (for Normal/Open terminal) DTC B1527: Seat 
belt switch (LH) circuit open (for COM terminal) DTC B1528: Seat belt switch (LH) circuit (ground side) 
shorted (for COM terminal) DTC B1529: Seat belt switch (LH) circuit (power supply side) shorted (for 
COM terminal)

CAUTION

If DTC B1520, B1521, B1522, B1523, B1524, 
B1525, B1526, B1527, B1528 or B1529 are set in 
the combination meter, always diagnose the CAN 
bus lines.

.

CIRCUIT OPERATION

The SRS-ECU determines whether the seat belt is 
fastened or not according to the connection location 
of the seat belt switch in the seat buckle.

.

Driver's Seat Belt Switch Circuit

SEAT BELT 
SWITCH (DRIVER'S SIDE)
DETECTION CIRCUIT

SEAT BELT SWITCH
(DRIVER'S SIDE)

SRS-ECU

AC305362

CONNECTOR: C-122

C-122 (Y)

AE

SRS-ECU

AC305264

AQ

CONNECTOR: D-28

D-28 (B)