Mitsubishi 380. Manual - part 781

 

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Mitsubishi 380. Manual - part 781

 

 

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-48

STEP 6. Check the harness for short circuit to ground 
between SRS-ECU connector C-121 (terminal No.28 and 27 
) and clock spring connector C-307 (terminal No.13 and 
14).
Q: Are the harness wires between SRS-ECU connector 

C-121 (terminal No.28 and 27 ) and clock spring 
connector C-307 (terminal No.13 and 14) 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.

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 B1403  set?

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

52DB008A

C-307 (Y)

CONNECTOR: C-307

C-307 HARNESS

SIDE CONNECTOR

CLOCK

SPRING

11

12

13

14

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-49

DTC B1406: Front Impact Sensor (RH) System for Fault 1 DTC B1416: Front Impact Sensor (LH) 
System for Fault 1

CAUTION

If DTC B1406 or B1416 is set in the SRS-ECU, 
always diagnose the CAN main bus line.

.

DTC SET CONDITIONS

These DTCs are set if the following conditions are 
detected from the analog G-sensor inside the front 
impact sensor output:

• Analog G-sensor is not operating.

• Analog G-sensor characteristics are abnormal.

• Analog G-sensor output is abnormal.

.

TROUBLESHOOTING HINTS

Malfunction of front impact sensor (RH) (for DTC 
B1406) and front impact sensor (LH) (for DTC 
B1416)

• Refer to circuit diagrams GROUP-

90

• Refer to configuration diagrams GROUP-

80

.

DIAGNOSIS

Required Special Tool:

• 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)

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 ).

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-50

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 ).

STEP 3. Check the front impact sensor. (Using diagnostic 
tool MB991958, read the diagnostic trouble code.)
Replace front impact sensor (RH) and front impact sensor (LH) 
(for DTC B1416) (Refer to 

P.52B-231

).

Check the diagnostic trouble code.

Q: Is either DTC B1406 or B1416 set?

YES : Replace the SRS-ECU (Refer to 

P.52B-234

).

NO :  The procedure is complete.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-51

DTC B1407: Front Impact Sensor (RH) Power Supply Circuit System

CAUTION

If DTC B1407 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 (RH) remains less than a pre-
determined value for five seconds. However, if the 
system returns to normal condition, code number 
B1407 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 (RH)

• 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)

AC305206

A-27 (Y)

BC

CONNECTOR: A-27

52DB013A

CONNECTOR: C-29

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)

 

 

 

 

 

 

 

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