Mitsubishi Galant (2004+). Manual - part 1542

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-61

STEP 6. Check the harness for short circuit to power 
supply between SRS-ECU connector C-121 (terminal No.36 
and 37 <1st squib> or terminal No.33 and 34 <2nd squib>) 
and clock spring connector C-307 (terminal No.13 and 14 
or terminal No. 11 and 12 <2nd squib>).

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 the SRS-ECU connector 

C-121 (terminal No.36 and 37 <1st squib> or terminal 
No.33 and 34 <2nd squib>) and clock spring connector 
C-307 (terminal No.13 and 14 or terminal No. 11 and 12 
<2nd squib>) in good condition?
YES : Go to Step 7.
NO :  Replace the harness wires between SRS-ECU 

connector C-121 and clock spring connector C-307. 
Then go to Step 7.

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

AC305233

C-22 (Y)

CO

CONNECTOR: C-22

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-62

STEP 7. 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 B1402 <1st squib> or B1482 <2nd squib> set?

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

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-63

DTC 1403: Driver’s Air Bag Module (1st Squib) System Fault for Ground Circuit (Short-Circuited to 
Ground)
DTC 1483: Driver’s Air Bag Module (2nd Squib) System Fault for Ground Circuit (Short-Circuited to 
Ground)

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

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-64

CAUTION

If DTC B1403 <1st squib> or B1483 <2nd squib> 
is set in the SRS-ECU, always diagnose the CAN 
main bus line.

.

CIRCUIT OPERATION

• The SRS-ECU judges how severe a collision is 

by detecting signals from the front impact sensors 
and the front air bag analog G-sensor. If the 
impact is over a predetermined level, the 
SRS-ECU sends an ignition signal. At this time, if 
the front air bag safing G-sensor is on, the SRS 
air bag will inflate. 

• The ignition signal is sent to the air bag module 

via the clock spring to inflate the air bag.

.

DTC SET CONDITIONS
This DTC is set if there is abnormal resistance 
between the input terminals of the driver's air bag 
module (squib). However, if no DTC resets, the SRS 
warning light will be switched off (DTC will be 
retained). 

.

TROUBLESHOOTING HINTS

• Malfunction of the clock spring

• Damaged harness wires and connectors

• Short to the ground in the driver's air bag module 

(squib) harness

• Malfunction of the SRS-ECU

.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A (Vehicles with CAN 

Communication System)

• MB991865: Dummy resistor

• MB991866: Resister harness

AC305235AP

C-307 (Y)

CONNECTORS: C-305, C-307

CLOCK
SPRING

C-305 (Y)