Mitsubishi 380. Manual - part 789

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-80

STEP 4. Check the passenger's air bag module circuit. 
Measure the resistance at the SRS-ECU connector C-121.
(1) Disconnect SRS-ECU connector C-121.

DANGER

To prevent the air bag from deploying unintentionally, 
disconnect the passenger’s air bag module connec-
tor C-110 to short the squib circuit.

(2) Unclip passenger’s air bag module connector C-110.
(3) Disconnect the passenger's air bag module connector 

C-110.

CAUTION

Do not insert a test probe into the terminal from its front 
side directly, as the connector contact pressure may be 
weakened.
(4) Check for continuity between C-121 harness side connector 

terminals 37 and 36, and body ground.
It should be open circuit.

Q: Does continuity exist? 

YES : Go to Step 5.
NO :  Erase the diagnostic trouble code memory, and check 

the diagnostic trouble code. If DTC B1413 sets, 
replace the SRS-ECU (Refer to 

P.52B-234

). Then go 

to Step 6.

24DB062A

CONNECTOR: C-121

C-121 (Y)

SRS-ECU

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

C-121

INSTRUMENT

HARNESS

CONNECTOR

(REAR VIEW)

52DB018A

C-110 (Y)

FRONT DECK
CROSSMEMBER

CONNECTOR: C-110

HARNESS SIDE 
CONNECTOR
(REAR VIEW)

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-81

STEP 5. Check the harness wires for short circuit to 
ground between SRS-ECU connector C-121 (terminal 
No.37 and 36) and passenger's air bag module connector 
C-110 (terminal No.1 and 2).
Q: Are the harness wires between SRS-ECU connector 

C-121 (terminal No.37 and 36) and passenger's air bag 
module connector C-110 (terminal No.1 and 2) in good 
condition? 
YES : Go to Step 6.
NO :  Replace the harness wires between SRS-ECU 

connector C-121 and passenger's air bag module 
connector C-110. 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 B1413 set?

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

52DB018A

C-110 (Y)

FRONT DECK
CROSSMEMBER

CONNECTOR: C-110

HARNESS SIDE 
CONNECTOR
(REAR VIEW)

24DB062A

CONNECTOR: C-121

C-121 (Y)

SRS-ECU

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

C-121

INSTRUMENT

HARNESS

CONNECTOR

(REAR VIEW)

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-82

DTC B1417: Front Impact Sensor (LH) Power Supply Circuit System

CAUTION

If DTC B1417 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION

The front 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 front air 
bags should be deployed, it sends a fire signal to the 
SRS-ECU to deploy the front air bags. In addition, 
the CPU diagnoses the internal components of the 
front impact sensor. If a malfunction occurs, it 
requests the SRS-ECU to set a diagnostic trouble 
code.

.

DTC SET CONDITIONS

This DTC will set when the power supply voltage to 
the front impact sensor (LH) remains less than a pre-
determined value for five seconds. However, if the 
system returns to normal condition, code number 
B1417 will be erased automatically and the SRS 
warning light will go out.

.

TROUBLESHOOTING HINTS

• Damaged wiring harness or connectors

• Malfunction of the front impact sensor (LH)

• Malfunction of the SRS-ECU

• Refer to circuit diagrams GROUP-

90

• Refer to configuration diagrams GROUP-

80

.

DIAGNOSIS

Required Special Tools:

• MB991958: diagnostic 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)

• MB991223 (MB991222): Harness set (Probe)

AC305210

CONNECTOR: A-23

AW

A-23 (Y)

52DB010A

CONNECTOR: C-11

24DB062A

CONNECTOR: C-121

C-121 (Y)

SRS-ECU

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

C-121

INSTRUMENT

HARNESS

CONNECTOR

(REAR VIEW)

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-83

STEP 1. Using diagnostic tool MB991958, diagnose the 
CAN bus line.

CAUTION

To prevent damage to diagnostic tool MB991958, always 
turn the ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting diagnostic tool 
MB991958.
(1) Connect diagnostic tool MB991958. Refer to "How to 

connect the diagnostic tool 

P.52B-19

."

(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 ).

STEP 2. 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 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 ).

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827