Mitsubishi Galant (2004+). Manual - part 1538

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-45

STEP 8. Check the driver’s air bag module circuit. Measure 
the resistance at SRS-ECU connector C-121.

(1) Disconnect SRS-ECU connector C-121.

DANGER

To prevent the air bag from deploying unintentionally, 
disconnect clock spring connector C-307 to short the 
squib circuit.

(2) Disconnect clock spring connector C-307.

CAUTION

Insert an insulator such as a cable tie to a depth of 4mm 
(0.16 inch) or more, otherwise the short spring will not be 
released.
(3) Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch) 

thick] between terminals 36, 37 <1st squib> or 33, 34 <2nd 
squib> and the short spring to release the short spring.

AC305362

CONNECTOR: C-121

C-121 (Y)

AH

SRS-ECU

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

AC305235AK

C-307 (Y)

CONNECTOR: C-307

C-307 HARNESS
SIDE CONNECTOR

CLOCK
SPRING

11

12

13

14

AC308144

SECTION
A - A

C-121 HARNESS SIDE 
CONNECTOR
(FRONT VIEW)

CABLE TIE

SHORT SPRING

4 mm OR MORE

TERMINAL

A

AB

A

<1ST SQUIB>

AC308141

SECTION
A - A

C-121 HARNESS SIDE 
CONNECTOR
(FRONT VIEW)

CABLE TIE

SHORT SPRING

4 mm OR MORE

TERMINAL

AB

<2ND SQUIB>

A

A

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-46

CAUTION

Do not insert a test probe into the terminal from its front 
side directly as the connector contact pressure may be 
weakened.
(4) Check for continuity between C-26 harness side connector 

terminals 36 and 37 <1st squib> or 33 and 34 <2nd squib>.

It should be open circuit.

Q: Does continuity exist? 

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1400 <1st 
squib> or B1481 <2nd squib> set, replace the 
SRS-ECU. (Refer to 

P.52B-365

). Then go to Step 10.

NO :  Go to Step 9. 

STEP 9. Check the harness for short circuit between 
SRS-ECU connector C-121 (terminal No.36 and 37 <1st 

squib> or No.33 and 34 <2nd squib>) and clock spring 
connector C-307 (terminal No.13 and 14 <1st squib> or 
No.11 and 12 <2nd squib>).

AC301581

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-121 HARNESS SIDE 
CONNECTOR (REAR VIEW)

<1ST SQUIB>

AC

AC308145

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-121 HARNESS SIDE 
CONNECTOR (REAR VIEW)

<2ND SQUIB>

AB

AC305362

CONNECTOR: C-121

C-121 (Y)

AH

SRS-ECU

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

AC305235AK

C-307 (Y)

CONNECTOR: C-307

C-307 HARNESS
SIDE CONNECTOR

CLOCK
SPRING

11

12

13

14

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-47

NOTE: After inspecting intermediate connector C-22 inspect 
the wiring harness. If the intermediate connector C-22 is dam-
aged, repair or replace it.
Q: Are harness wires between SRS-ECU connector C-121 

(terminal No.36 and 37 <1st squib> or No.33 and 34 
<2nd squib>) and clock spring connector C-307 
(terminal No.13 and 14 <1st squib> or No.11 and 12 <2nd 
squib>) in good condition?
YES : Go to Step 10.
NO :  Replace the harness wires between SRS-ECU 

connector C-121 and clock spring connector C-307. 
Then go to Step 10.

STEP 10. 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 B1400 <1st squib> or B1480 <2nd squib> set?

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

AC305233

C-22 (Y)

CO

CONNECTOR: C-22

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-48

DTC B1401: Driver's Air Bag Module (1st Squib) System Fault 2 (Open in the Squib Circuit)
DTC B1481: Driver's Air Bag Module (2nd Squib) System Fault 2 (Open in the Squib Circuit)

AIR BAG MODULE
(SQUIB)
(DRIVER'S SIDE)

CLOCK 
SPRING

AIR BAG DRIVE CIRCUIT

SRS-ECU

: CONNECTOR LOCK SWITCH 
  CONNECTOR CONNECTED: ON
  CONNECTOR DISCONNECTED: OFF

CONNECTOR
LOCK SWITCH

Driver's Air Bag Module (1st and 2nd Squib) Circuit

AC305233 AO

CONNECTOR: C-22

C-22 (Y)

AC305362

CONNECTOR: C-121

C-121 (Y)

AD

SRS-ECU