Mitsubishi Galant 9G. Manual - part 1439

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-166

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

Q: Is the check result satisfactory?

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

Diagnosis-Can Bus Diagnostic Chart ). 

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-167

STEP 3. Check the side-airbag module (LH). (Using scan 
tool MB991958, read the diagnostic trouble code.)
(1) Disconnect the negative battery terminal.
(2) Disconnect the side-airbag module (LH) connector D-24.

(3) Connect special tool MB991865 to special tool MB991866.

CAUTION

Do not insert a test probe into the terminal from its front 
side directly, as the connector contact pressure may be 
weakened.
(4) Insert special tool MB991866 into the D-24 harness side 

connector by backprobing.

(5) Connect the negative battery terminal.
(6) Erase the diagnostic trouble code memory, and check the 

diagnostic trouble code.

Q:  Is DTC B1432 set?

YES : Go to Step 4.
NO :  Replace the seatback frame of the front seat (LH) 

(Refer to GROUP 52A, Front Seat 

P.52A-25

). Then 

go to Step 6.

AC307778

CONNECTOR : D-24

AC

D-24 (R)

2

1

HARNESS SIDE
CONNECTOR
(REAR VIEW)

AC006042 BP

MB991866
(RESISTOR HARNESS)

D-24 HARNESS SIDE
CONNECTOR

D-24 SIDE-AIRBAG 
MODULE (LH) CONNECTOR

MB991865 (DUMMY 
RESISTOR: 3

 

Ω

)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-168

STEP 4. Check the side-airbag module (RH) circuit. 
Measure the voltage at the SRS-ECU connector C-122.
(1) Disconnect SRS-ECU connector C-122.

DANGER

To prevent the air bag from deploying unintentionally, 
disconnect the side-airbag module (LH) connector 
D-24 to short the squib circuit.

(2) Disconnect left hand side-airbag module (LH) connector 

D-24.

(3) 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.
(4) Measure the voltage between C-122 harness side 

connector terminals 9, 10 and body ground.
Voltage should measure 0 volt.

Q: Is the measured voltage within the specified range? 

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1432 sets, 
replace the SRS-ECU (Refer to 

P.52B-365

). Then go 

to Step 6.

NO :  Go to Step 5. 

AC305362

CONNECTOR: C-122

C-122 (Y)

AI

SRS-ECU

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

AC307778

CONNECTOR : D-24

AC

D-24 (R)

2

1

HARNESS SIDE
CONNECTOR
(REAR VIEW)

AC308177

A

B

18

10

15

7

13

5

14

6

16

8

17

9

19

11

20

12

1 2

3 4

C-122 HARNESS SIDE
CONNECTOR
(REAR VIEW)

AB 

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-169

STEP 5. Check the harness wires for short circuit to power 
supply between SRS-ECU connector C-122 (terminal No.9 
and 10) and side-airbag module (LH) connector D-24 
(terminal No.1 and 2). 
Q: Are the harness wires between SRS-ECU connector 

C-122 (terminal No.9 and 10) and side-airbag module 
(LH) connector D-24 (terminal No.1 and 2) in good 
condition?
YES : Go to Step 6.
NO :  Replace the harness wires between SRS-ECU 

connector C-122 and side-airbag module (LH) 
connector D-24. Then go to Step 6.

STEP 6. 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 B1432 set?

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

AC305362

CONNECTOR: C-122

C-122 (Y)

AI

SRS-ECU

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

AC307778

CONNECTOR : D-24

AC

D-24 (R)

2

1

HARNESS SIDE
CONNECTOR
(REAR VIEW)

AC206894

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827