Mitsubishi Galant 9G. Manual - part 1457

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-238

STEP 1. Using scan tool MB991958, diagnose the CAN bus 
line.

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. Refer to "How to connect the 

scan tool 

P.52B-30

."

(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the CAN bus line found to be normal?

YES : Go to Step 2.
NO :  Repair the CAN bus line (Refer to GROUP 54C, 

Diagnosis ).

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

Q: Is the DTC set?

YES : Go to Step 3.
NO :  There is an intermittent malfunction such as poor 

engaged connector(s) or open circuit (Refer to 
GROUP 00, How to Use Troubleshooting/Inspection 
Service Points 

− How to Cope with Intermittent 

Malfunctions ).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-239

STEP 3. Check junction block fuse number 22 <DTC 
B1476> or 23 <DTC B1477>.

Q: Is the fuse burned out?

YES : Go to Step 6.
NO :  Go to Step 4.

STEP 4. Check the power supply circuit for open circuit. 
Measure the voltage at SRS-ECU connector C-121.
(1) Disconnect the negative battery terminal.
(2) Disconnect SRS-ECU connector C-121.
(3) Connect the negative battery terminal.
(4) Turn the ignition switch to the "ON" position.

CAUTION

Do not insert a test probe into the terminal from its front 
side directly, as the connector contact pressure may be 
weakened.
(5) Measure the voltage between C-121 harness side 

connector terminal 23 <DTC B1476> or 24 <DTC B1477> 
and body ground.
Voltage should measure 9 volts or more.

Q: Is the measured voltage within the specified range?

YES : Erase the diagnosis connector memory, and check 

the diagnostic trouble code. If DTC B1476 or B1477 
set, replace the SRS-ECU (Refer to 

P.52B-365

). 

Then go to Step 10.

NO :  Go to Step 5.

AC308194

AB

FUSE No. 23

JUNCTION
BLOCK

FUSE No. 22

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

AC308202

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)

AB

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-240

STEP 5. Check the harness for open circuit between 
SRS-ECU connector C-121 (terminal No.23 <DTC B1476> 
or terminal No.24 <DTC B1477>) and the ignition switch 
connector C-308 (terminal No.2).

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

AC305235AG

CONNECTOR: C-308

C-308

2
5

4

1

6

3

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-241

NOTE: After inspecting intermediate connectors C-22, C-211 
and C-215, inspect the wiring harness. If intermediate connec-
tors are damaged, repair or replace them. Refer to GROUP 
00E, Harness Connector Inspection . Then go to Step 10.

Q: Is the harness wire between SRS-ECU connector C-121 

(terminal No.23 <DTC B1476> or terminal No.24 <DTC 
B1477>) and the ignition switch connector C-308 
(terminal No.2) in good condition?
YES : Go to Step 10.
NO :  Replace the harness wire between SRS-ECU 

connector C-121 and the ignition switch connector 
C-308. Then go to Step 10.

STEP 6. Check a burned-out fuse.
(1) Replace the fuse.
(2) Turn the ignition switch to the "ON" position, wait for at least 

one minute and then turn the ignition switch to the "LOCK" 
(OFF) position. 

(3) Check the fuse.

Q: Is the fuse in good condition?

YES : Go to Step 10.
NO :  It is possible that the circuit using fuse No22 <DTC 

B1476> or No.23 <DTC B1477> is shorted, go to Step 
7.

AC305233 AI

CONNECTOR: C-22

C-22 (Y)

AC305416

CONNECTORS: C-211, C-215

JUNCTION BLOCK 
(FRONT VIEW)

C-215

C-211

HARNESS SIDE

C-211

HARNESS SIDE

C-215

AK