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)