Mitsubishi Galant (2004+). Manual - part 1570

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-173

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 Cope with Intermittent 
Malfunction 

P.00-6

).

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 B1433 set?

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

(Refer to GROUP 52A, Front Seat 

P.52A-26

). Then 

go to Step 6.

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

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-174

STEP 4. Check the side-airbag module (LH) circuit. 
Measure the resistance at the SRS-ECU connector C-122.

(1) Disconnect SRS-ECU connector C-122.

(2) Disconnect side-airbag module (LH) connector D-24.

CAUTION

Do not insert a test probe into the terminal from its front 
side directly, as the connector contact pressure may be 
weakened.
(3) Check for continuity between C-122 harness side connector 

terminals 9, 10 and body ground.

It should be open circuit.

Q: Does continuity exist? 

YES : Erase the diagnostic trouble code from memory, and 

check the diagnostic trouble code. If DTC B1433 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)

AC308178

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-175

STEP 5. Check the harness wires for short circuit to 
ground 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 B1433 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)

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-176

DTC B1437: Side Impact Sensor (LH) Power Supply Circuit System

CAUTION

If DTC B1437 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION
The side impact sensor includes an analog G sensor 
and CPU, etc. The CPU monitors the analog G sen-
sor output signal. If the CPU judges that the 
side-airbags should be deployed, it sends a fire sig-
nal to the SRS-ECU to deploy the side-airbags. In 
addition, the CPU diagnoses the internal compo-
nents of the side impact sensor. If a malfunction 
occurs, it requests the SRS-ECU to set a diagnostic 
trouble code.

.

DTC SET CONDITIONS
This DTC is set if the power supply voltage of the 
side impact sensor (LH) drops below the rated value 
for a continuous period of 5 seconds or more. How-
ever, DTC B1437 will be automatically cleared and 
the SRS warning light will switch off if the condition 
returns to normal. 

.

TROUBLESHOOTING HINTS

• Damaged wiring harnesses or connectors

• Malfunction of the side-airbag module (LH) 

(squib)

• Malfunction of the SRS-ECU

.

SIDE IMPACT 
SENSOR (LH)

INTERFACE 
CIRCUIT

SRS-ECU

Side Impact Sensor (LH) Circuit

AC305362

CONNECTOR: C-122

C-122 (Y)

AE

SRS-ECU

AC305250

CONNECTOR: D-21

AC

FRONT SEAT BELT