Mitsubishi Grandis. Manual — part 998

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-44

CAUTION

If diagnosis code B1410 <1st squib> or B1490
<2nd squib> is set in the SRS-ECU, always
diagnose the CAN main bus line.

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 input to the air bag module

via the clock spring to inflate the air bag.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal
resistance between the input terminals of the
passenger's side air bag module (squib). However, if
no diagnosis code reset, the SRS warning lamp will
be switched off (diagnosis code will be retained).

PROBABLE CAUSES

• Improper engaged connector or defective short

spring*

• Short circuit between the passenger's air bag

module (squib) circuit terminals

• Damaged connector(s)

• Malfunction of the SRS-ECU

NOTE: *: The squib circuit connectors integrate a
"short" spring (which prevents the air bag from
deploying unintentionally due to static electricity by
shorting the positive wire to the earth wire in the
squib circuit when the connectors are disconnected).
(Refer to

P.52B-5

). Therefore, if connector C-119 or

C-108 is damaged or improperly engaged, the short
spring may not be released when the connector is
connected.

DIAGNOSIS PROCEDURE

STEP 1. MUT-III CAN bus diagnostics

Use the MUT-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES :

Go to Step 2.

NO :

Repair the CAN bus line (Refer to GROUP
54D, Diagnosis

P.54D-16

).

STEP 2. Check whether the diagnosis code is
reset.

Check again if the diagnosis code is set.
(1) Erase the diagnosis code.
(2) Ignition: LOCK (OFF) position to ON
(3) On completion, check that the diagnosis code is

not reset.

Q: Is the diagnosis code 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 Cope with
Intermittent Malfunction

P.00-5

).

STEP 3. MUT-III diagnosis code

CAUTION

To prevent damage to MUT-III, always turn the
ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting MUT-III.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the diagnosis code is set.
(3) Turn the ignition switch to the "LOOK" (OFF)

position.

Q: Is diagnosis code B1519 set?

YES :

Go to Step 4.

NO :

Go to Step 5.

STEP 4. Connector check: SRS-ECU connector
C-119

Q: Is the connector correctly engaged?

YES :

Go to Step 5.

NO :

Engage the connector correctly. Then go to
Step 9.

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-45

STEP 5. Connector check: SRS-ECU connector
C-119 and passenger’s air bag module connector
C-108 (MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.

(2) Disconnect connectors C-119 and C-108, and

then reconnect them.

(3) Slide the outer housing of the clock spring side of

passenger’s air bag module connector C-108 in
the arrow direction shown, and disconnect the
connector.

(4) Connect the negative battery terminal.
(5) Erase the diagnosis code memory, and check the

diagnosis code.

Q: Is diagnosis code B1410 <1st squib> or B1490

<2nd squib> set?

YES :

Go to Step 6.

NO :

The procedure is complete. It is assumed
that diagnosis code B1410 <1st squib> or
B1490 <2nd squib> set as connector C-119
or C-108 was engaged improperly.

STEP 6. Check the passenger's air bag module.
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.

(2) Disconnect the passenger’s air bag module

connector C-108.

(3) Slide the outer housing of the clock spring side of

passenger’s air bag module connector C-108 in
the arrow direction shown, and disconnect the

AC311438 AD

C-119 (Y)

Connector: C-119

Harness side
(front view)

AC311373AC

C-108 (Y)

Connector: C-108 <LHD>

Harness side
(front view)

AC311375 AB

C-108 (Y)

Connector: C-108 <RHD>

Harness side
(front view)

AC306561AI

Outer housing of the passenger's
air bag module connector C-108

AC311373AC

C-108 (Y)

Connector: C-108 <LHD>

Harness side
(front view)

AC311375 AB

C-108 (Y)

Connector: C-108 <RHD>

Harness side
(front view)

AC306561AI

Outer housing of the passenger's
air bag module connector C-108

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-46

connector.

(4) Connect special tool dummy resistor (MB991865)

to special tool resistor harness (MB991866).

CAUTION

Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(5) Insert special tool MB991866 into the harness

side connector C-108 (terminal No.1 and 2 <1st
squib> or terminal No.3 and 4 <2nd squib>) by
backprobing.

(6) Connect the negative battery terminal.

CAUTION

Always diagnosis code B1491 is set when
checking diagnosis code B1410. This is because
the second side terminal is isolated when
checking it, diagnosis code B1491 is set but this
is not a fault. In addition, always diagnosis code
B1411 is set when checking diagnosis code
B1490 because the first side terminal is isolated.
(7) Erase the diagnosis code memory, and check the

diagnosis code.

Q: Is the checked diagnosis code set?

YES :

Go to Step 7.

NO :

Replace the passenger's air bag module
(Refer to

P.52B-225

). Then go to Step 9.

STEP 7. Check the passenger’s air bag module
circuit at SRS-ECU connector C-119.

(1) Disconnect SRS-ECU connector C-119.

DANGER

To prevent the air bag from deploying
unintentionally, disconnect the passenger’s
air bag module connector C-108 to short the
squib circuit.

(2) Disconnect the passenger's air bag module

AC306760

AC306760AD

MB991865 (Dummy
resistor: 3

Ω)

MB991866
(Resistor harness)

C-108 Harness
connector

C-108
Passenger's
air bag module
connector

AC311438 AD

C-119 (Y)

Connector: C-119

Harness side
(front view)

AC311373AC

C-108 (Y)

Connector: C-108 <LHD>

Harness side
(front view)

AC311375 AB

C-108 (Y)

Connector: C-108 <RHD>

Harness side
(front view)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-47

connector C-108.

(3) Slide the outer housing of the clock spring side of

passenger’s air bag module connector C-108 in
the arrow direction shown, and disconnect the
connector.

CAUTION

Insert an insulator such as a cable tie to a depth
of 4mm or more, otherwise the short spring will
not be released.
(4) Insert a cable tie [3 mm wide, 0.5 mm thick]

between terminals 27 and 28 <1st squib> or 30
and 31 <2nd squib>, and the short spring to
release the short spring.

CAUTION

Do not insert a test probe into the terminal from
its front side directly as the connector contact
pressure may be weakened.
(5) Check for continuity between C-119 harness side

connector terminals 27 and 28 <1st squib> or 30
and 31 <2nd squib>.

OK: Open circuit

Q: Is the check result normal?

YES :

Erase the diagnosis code memory, and

check the diagnosis code. If diagnosis code
B1410 <1st squib> or B1490 <2nd squib>
set, replace the SRS-ECU. (Refer to

P.52B-223

). Then go to Step 9.

NO :

Go to Step 8.

AC306561AI

Outer housing of the passenger's
air bag module connector C-108

AC308143

Section
A - A

C-119 Harness side
connector
(front view)

Cable tie

Short spring

4 mm or more

Terminal

AD

<1st squib>

A

A

AC308142

Section
A - A

C-119 Harness side
connector
(front view)

Cable tie

Short spring

4 mm or more

Terminal

AD

<2nd squib>

A

A

AC301582

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-119 Harness side
connector (rear view)

<1st squib>

AE

AC308150

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-119 Harness side
connector (rear view)

<2nd squib>

AD