Mitsubishi Galant (2004+). Manual - part 1592

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-261

STEP 5. Check the harness between SRS-ECU connector 
C-121 (terminal No.42) and passenger’s seat belt warning 
light C-07 (terminal No.3).

• Check the passenger’s seat belt warning light output lines 

for open circuit.

NOTE: After inspecting intermediate connector C-22 inspect 
the wiring harness. If intermediate connector C-22 is damaged, 
repair or replace them. Refer to GROUP 00E, Harness Con-
nector Inspection 

P.00E-2

. Then go to Step 6 .

Q: Is the check result satisfactory?

YES : Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1487 sets, 
replace the SRS-ECU. (Refer to 

P.52B-365

.) Then go 

to Step 6 .

NO :  Repair the harness wires. Then go to Step 6 .

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

AC305233CZ

CONNECTOR: C-07

HARNESS SIDE

AC305233 AI

CONNECTOR: C-22

C-22 (Y)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-262

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 B1487 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-263

DTC B1488: Passenger’s Air Bag OFF Indicator Light Drive Circuit System Fault 2.

CAUTION

If DTC B1488 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION

• Power for the passenger’s air bag OFF indicator 

light is supplied from the ignition switch (IG1).

• The passenger’s air bag OFF indicator light illu-

minates when the ignition switch is turned to the 
"ON" position and goes out after approximately 
seven seconds if there is not a malfunction in the 
SRS system.

.

SRS-ECU

IGNITION
SWITCH (IG1)

JUNCTION
BLOCK

AIR BAG OFF
INDICATOR
LIGHT
(PASSEGER'S SIDE)

RELAY
BOX

JOINT
CONNECTOR (1)

TAILLIGHT
RELAY

FRONT ECU

AIR BAG OFF
INDICATOR LIGHT
DRIVE CIRCUIT

JUNCTION
BLOCK

Air Bag OFF Indicator Light Drive Circuit

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-264

DTC SET CONDITIONS

• This DTC is set under one of the following cases 

while the SRS-ECU is monitoring the passen-
ger’s air bag OFF indicator light drive circuit:

• When a short circuit occurs in the passen-

ger’s air bag OFF indicator light drive circuit.

• When a malfunction is detected in the output 

transistor inside the SRS-ECU.

However, if the vehicle condition returns to normal, 
DTC B1488 will be automatically erased, and the 
assenger’s air bag OFF indicator light will go out.

.

TROUBLESHOOTING HINTS

• Damaged wiring harnesses or connectors

• 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)

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 

P.54C-14

).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827