Mitsubishi Grandis. Manual — part 1005

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-72

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 B1422 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

).

Code No.B1423: Side-Airbag Module (RH) (Squib) System Fault Power Supply Circuit (Short-Circuited
to Power Supply)

CAUTION

If diagnosis code B1423 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 the power supply in the side-airbag

module (RH) (squib) harness

• Malfunction of the SRS-ECU

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-73

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. Recheck for diagnosis code.

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 B1423 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. Voltage 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.

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)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-74

(3) Turn the ignition switch to the "ON" position.

CAUTION

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

side connector terminals 57 and 58 and body
earth.

OK: 0 V

Q: Is the check result 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 B1423 set?

YES :

Return to Step 1.

NO :

The procedure is complete.

Code No.B1426: Side Impact Sensor (RH) System for Fault 1
Code No.B1436: Side Impact Sensor (LH) System for Fault 1

CAUTION

If diagnosis code B1426 or B1436 is set in the
SRS-ECU, always diagnose the CAN main bus
line.

DIAGNOSIS CODE SET CONDITIONS

These diagnosis codes are set if the following
conditions are detected from the analogue G-sensor
inside the side impact sensor output:

• Analogue G-sensor is not operating.

• Analogue G-sensor characteristics are abnormal.

• Analogue G-sensor output is abnormal.

PROBABLE CAUSES

Malfunction of side impact sensor (RH) (for diagnosis
code B1426) and side impact sensor (LH) (for
diagnosis code B1436)

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. Check the side impact sensor. (MUT-III
diagnosis code.)

Replace side impact sensor (RH) (for diagnosis code
B1426) and side impact sensor (LH) (for diagnosis
code B1436) (Refer to

P.52B-236

).

Check the diagnosis code.

Q: Is either diagnosis code B1426 or B1436 set?

YES :

Replace the SRS-ECU (Refer to

P.52B-223

).

NO :

The procedure is complete.

AC301579

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

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-75

Code No.B1427: Side Impact Sensor (RH) Power Supply Circuit System

CAUTION

If diagnosis code B1427 is set in the SRS-ECU,
always diagnose the CAN main bus line.

OPERATION

The side impact sensor includes an analogue G
sensor and CPU, etc. The CPU monitors the
analogue G sensor output signal. If the CPU judges
that the side-airbags and curtain air bags should be
deployed, it sends a fire signal to the SRS-ECU to
deploy the side-airbags and curtain air bags. In
addition, the CPU diagnoses the internal
components of the side impact sensor. If a
malfunction occurs, it requests the SRS-ECU to set a
diagnosis code.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code will set when the power supply
voltage to the side impact sensor (RH) remains less
than a predetermined value for 5 seconds. However,
if the system returns to normal condition, code
number B1427 will be erased automatically and the
SRS warning lamp will go out.

PROBABLE CAUSES

• Damaged wiring harness or connectors

• Malfunction of the side impact sensor (RH)

• 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 line (Refer to GROUP
54, 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

).

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 IMPACT
SENSOR (FRONT: RH)

SRS-ECU

Side Impact Sensor (Front) (RH) Circuit