Mitsubishi Grandis. Manual - part 1004

 

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Mitsubishi Grandis. Manual - part 1004

 

 

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-68

CAUTION

If diagnosis code B1421 is set in the combination 
meter, always diagnose the CAN bus lines.

OPERATION

• The SRS-ECU judges how severe a collision is 

by detecting signals from the left and right side 
impact sensors. If the impact is over a 
predetermined level, the SRS-ECU sends an 
ignition signal. At this time, if the side-airbag 
safing G-sensor is on, the SRS side-airbag will 
inflate.

• The ignition signal is input to the side-airbag 

module to inflate the side-airbag.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal 
resistance between the input terminals of the 
side-airbag module (RH) (squib).

PROBABLE CAUSES

• Open circuit in the side-airbag module (RH) 

(squib) circuit

• Improper connector contact

• Malfunction of the SRS-ECU

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 lines (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. Check the side-airbag module (RH). 
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.

(2) Disconnect the side-airbag module (RH) 

connector D-29.

(3) 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.
(4) Insert special tool MB991866 into the D-29 

harness side connector by backprobing.

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

diagnosis code. 

Q: Is diagnosis code B1421 set?

YES : 

Go to Step 4.

NO : 

Replace the seatback frame of the front 
seat (RH). (Refer to GROUP 52A, Front 
Seat 

P.52A-24

). 

AC303522

AE

D-29 (R)

Connector: D-29

Harness side
(front view)

AC006042BX

MB991866
(Resistor harness)

D-29 Harness side
connector

D-29 Side-airbag
module (RH) connector

MB991865 (Dummy
resistor: 3

 

Ω)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-69

STEP 4. Resistance measurement between 
SRS-ECU connector C-118 (terminal No.57 and 
58) and the side-airbag module (RH) connector 
D-29 (terminal No.1 and 2).

(1) Disconnect SRS-ECU connector C-118 and 

side-airbag module (RH) connector D-29.

CAUTION

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

terminals.

• SRS-ECU connector C-118 (terminal No.57) 

and the side-airbag module (RH) connector 
D-29 (terminal No.2)

• SRS-ECU connector C-118 (terminal No.58) 

and the side-airbag module (RH) connector 
D-29 (terminal No.1)

OK: Less than 2 

Q: Are the check results normal?

YES : 

Go to Step 5.

NO : 

Repair the harness wires between 
SRS-ECU connector C-118 (terminal No.57 
and 58) and side-airbag module (RH) 
connector D-29 (terminal No.1 and 2).

STEP 5. Check whether the diagnosis code is 
reset.

Q: Is diagnosis code B1421 set?

YES : 

Replace the SRS-ECU (Refer to 

P.52B-223

). 

NO : 

An intermittent malfunction is suspected 
(Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

P.00-5

).

AC311438 AC

C-118 (Y)

Connector: C-118

Harness side
(front view)

AC303522

AE

D-29 (R)

Connector: D-29

Harness side
(front view)

AC301580

1 2

63

55

51

69

61

66

58

65

64

56 57

68

60

67

59

70

62

53

52 B

A

54

C-118
Harness side
connector
(rear view)

D-29 
Harness side
connector
(rear view)

AE

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-70

Code No.B1422: Side-Airbag Module (RH) (Squib) System Fault Earth Circuit (Short-Circuited to 
Earth)

CAUTION

If diagnosis code B1422 is set in the combination 
meter, always diagnose the CAN bus lines.

OPERATION

• The SRS-ECU judges how severe a collision is 

by detecting signals from the left and right side 
impact sensors. If the impact is over a 
predetermined level, the SRS-ECU sends an 
ignition signal. At this time, if the side-airbag 
safing G-sensor is on, the SRS side-airbag will 
inflate.

• The ignition signal is input to the side-airbag 

module to inflate the side-airbag.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal 
resistance between the input terminals of the 
side-airbag module (RH) (squib).

PROBABLE CAUSES

• Damaged wiring harnesses or connectors

• Short to earth in the side-airbag module (RH) 

(squib) harness

• Malfunction of the SRS-ECU

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 lines (Refer to GROUP 
54D, Diagnosis-Can Bus Diagnostic Chart 

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

).

Wire colour code
B : Black     LG : Light green     G : Green     L : Blue     W : White     Y : Yellow     SB : Sky blue
BR : Brown     O : Orange     GR : Gray     R : Red     P : Pink     V : Violet

SIDE AIR BAG
MODULE
(SQUIB) (RH)

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

: CONNECTOR 
  CONNECTED: ON
  CONNECTOR 
  DISCONNECTED: OFF

NOTE

Side-Airbag Module (RH) (Squib) Circuit

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-71

STEP 3. Check the side-airbag module (RH). 
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.

(2) Disconnect the side-airbag module (RH) 

connector D-29.

(3) 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.
(4) Insert special tool MB991866 into the D-29 

harness side connector by backprobing.

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

diagnosis code. 

Q: Is diagnosis code B1422 set?

YES : 

Go to Step 4.

NO : 

Replace the seatback frame of the front 
seat (RH). (Refer to GROUP 52A, Front 
Seat 

P.52A-24

).

STEP 4. Check the side-airbag module (RH) 
circuit. Resistance measurement at the SRS-ECU 
connector C-118.

(1) Disconnect SRS-ECU connector C-118.

DANGER

To prevent the air bag from deploying 
unintentionally, disconnect the side-airbag 
module (RH) connector D-29 to short the 
squib circuit.

(2) Disconnect side-airbag module (RH) connector 

D-29.

CAUTION

Do not insert a test probe into the terminal from 
its front side directly, as the connector contact 
pressure may be weakened.
(3) Check for continuity between C-118 harness side 

connector terminals 57, 58 and body earth.

OK: Open circuit

Q: Is the check result normal? 

AC303522

AE

D-29 (R)

Connector: D-29

Harness side
(front view)

AC006042BX

MB991866
(Resistor harness)

D-29 Harness side
connector

D-29 Side-airbag
module (RH) connector

MB991865 (Dummy
resistor: 3

 

Ω)

AC311438 AC

C-118 (Y)

Connector: C-118

Harness side
(front view)

AC303522

AE

D-29 (R)

Connector: D-29

Harness side
(front view)

AC301576

63

55

51

69

61

66

58

65

64

56 57

68

60

67

59

70

62

53

52 B

A

54

C-118 Harness side
connector (rear view)

AE

 

 

 

 

 

 

 

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