Mitsubishi Galant (2004+). Manual - part 1558

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-125

STEP 5. Check SRS-ECU connector C-120 and side-airbag 
module (RH) connector D-32. (Using scan tool MB991958, 
read the diagnostic trouble code.)

(1) Disconnect the negative battery terminal.
(2) Disconnect connectors C-120 and D-32, and then 

reconnect them.

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

diagnostic trouble code.

Q: Is DTC B1420 out put?

YES : Go to Step 6.
NO :  The procedure is complete. It is assumed that DTC 

B1420 set because connector C-120 or D-32 was 
engaged improperly.

AC305362

CONNECTOR: C-120

C-120 (Y)

AG

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)

AC307779

D-32 (R)

AD

2

1

HARNESS SIDE
CONNECTOR
(REAR VIEW)

CONNECTOR : D-32

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-126

STEP 6. Check the side-airbag module (RH). (Using scan 
tool MB991958, read the diagnostic trouble code.)

(1) Disconnect the negative battery terminal.
(2) Disconnect the side-airbag module (RH) connector D-32.

(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-32 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 B1420 set?

YES : Go to Step 7.
NO :  Replace the seatback frame of the front seat (RH). 

(Refer to GROUP 52A, Front Seat 

P.52A-26

). Then 

go to Step 9.

AC307779

D-32 (R)

AD

2

1

HARNESS SIDE
CONNECTOR
(REAR VIEW)

CONNECTOR : D-32

AC006042BO

MB991866
(RESISTOR HARNESS)

D-32 HARNESS SIDE
CONNECTOR

D-32 SIDE-AIRBAG 
MODULE (RH) CONNECTOR

MB991865 (DUMMY 
RESISTOR: 3

 

Ω)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-127

STEP 7. Check the side-airbag module (RH) circuit. 
Measure the resistance at the SRS-ECU connector C-120.

(1) Disconnect SRS-ECU connector C-120.

DANGER

To prevent the air bag from deploying unintentionally, 
disconnect the side-airbag module (RH) connector 
D-32 to short the squib circuit.

(2) Disconnect side-airbag module connector D-32.

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 57, 58 and the short spring to 
release the short spring.

(4) Measure at the wiring harness side.

CAUTION

Do not insert a test probe into the terminal from its front 
side directly, as the connector contact pressure may be 
weakened.
(5) Check for continuity between C-120 harness side connector 

terminals 57 and 58.
It should be open circuit.

Q: Does continuity exist?

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1420 sets, 
replace the SRS-ECU. (Refer to 

P.52B-365

). Then go 

to Step 7.

NO :  Go to Step 8.

AC305362

CONNECTOR: C-120

C-120 (Y)

AG

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)

AC307779

D-32 (R)

AD

2

1

HARNESS SIDE
CONNECTOR
(REAR VIEW)

CONNECTOR : D-32

AC301607AC

C-120 HARNESS SIDE
CONNECTOR (FRONT VIEW)

TERMINAL

CABLE
TIE

SECT-
ION
A - A

4 mm (0.16 inch) OR MORE

SHORT SPRING

A

A

AC301573

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)

AD

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-128

STEP 8. Check the harness wires for short circuit between 
SRS-ECU connector C-120 (terminal No.57 and 58) and 
side-airbag module (RH) connector D-32 (terminal No.1 
and 2).

Q: Are the harness wires between SRS-ECU connector 

C-120 (terminal No.57 and 58) and side-airbag module 
(RH) connector D-32 (terminal No.1 and 2) in good 
condition?
YES : Go to Step 9.
NO :  Repair the harness wires between SRS-ECU 

connector C-120 and side-airbag module (RH) 
connector D-32. Then go to Step 9.

STEP 9. 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 B1420 set?

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

AC305362

CONNECTOR: C-120

C-120 (Y)

AG

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)

AC307779

D-32 (R)

AD

2

1

HARNESS SIDE
CONNECTOR
(REAR VIEW)

CONNECTOR : D-32

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827