Mitsubishi Grandis. Manual — part 1010

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-92

Code No.B1438: Side Impact Sensor (LH) (Squib) for Power Supply Circuit
Code No.B1439: Side Impact Sensor (LH) (Squib) for Communication System

CAUTION

If diagnosis code B1438 or B1439 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

These diagnosis codes are set if communication
between the side impact sensor (LH) and the
SRS-ECU is not possible or faulty.

PROBABLE CAUSES

• Damaged wiring harnesses or connectors

• Malfunction of the side impact sensor (LH)

• 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
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 (LH).
(MUT-III diagnosis code.)
(1) Disconnect the negative battery terminal.
(2) Replace the side impact sensor (LH) with the side

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: LH)

SRS-ECU

Side Impact Sensor (Front) (LH) Circuit

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-93

impact sensor (RH).

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

the diagnosis code.

Q: Is diagnosis code B1428 or B1429 set?

YES :

Replace the side impact sensor (LH) with a

new one. (Refer to

P.52B-236

). Go to Step

5.

NO :

Go to Step 4.

STEP 4. Check the harness wires for open circuit
or short circuit between SRS-ECU connector
C-120 (terminal No.19 and 20) and side impact
sensor (LH) connector D-18 (terminal No.1 and
2).

Q: Are the harness wires between SRS-ECU

connector C-120 (terminal No.19 and 20) and side

impact sensor (LH) connector D-18 (terminal No.1
and 2) in good condition?

YES :

Go to Step 5.

NO :

Repair the harness wires between
SRS-ECU connector C-120 (terminal No.19
and 20) and side impact sensor (LH)
connector D-18 (terminal No.1 and 2).

STEP 5. Check whether the diagnosis code is
reset.

Q: Is diagnosis code B1438 or B1439 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 AE

C-120 (Y)

Connector: C-120

Harness side
(front view)

AC302579AC

D-18 (Y)

Connector: D-18

Centre
pillar

Front vehicle

Harness side
(front view)

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-94

Code No.B1440: Curtain air bag module (squib) (RH) system (short-circuited between terminals of the
squib circuit)

CAUTION

If diagnosis code B1440 is set in the SRS-ECU,
always diagnose the CAN bus lines.

OPERATION

The SRS-ECU judges how severe a collision is by
detecting signals from the side impact sensors and
the side-airbag safing G-sensor. If the impact is over
a predetermined level, the SRS-ECU outputs an
ignition signal. At this time, if the side air bag safing
G-sensor is on, the curtain air bag module will
deploy.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if one curtain air bag
module squib (RH) wire shorted to the other.
However, if no diagnosis code resets, 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 curtain air bag module

(squib) (RH) 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).
Therefore, if connector C-118 or G-04 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 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.

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

SRS-ECU

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK SWITCH

: CONNECTOR
CONNECTED: ON
CONNECTOR
DISCONNECTED: OFF

NOTE

CURTAIN AIR BAG
MODULE
(SQUIB) (RH)

Curtain Air Bag Module (Squib) (RH) Circuit

TROUBLESHOOTING

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-95

(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-II/III, always turn the
ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting MUT-II/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 lock check: SRS-ECU
connector C-118 (MUT-III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) Disconnect connectors C-118, and then

reconnect them.

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

diagnosis code.

Q: Is diagnosis code B1440 set?

YES :

Go to Step 6.

NO :

The procedure is complete. It is assumed
that diagnosis code B1440 set as connector
C-118 was engaged improperly.

STEP 5. Connector lock check: SRS-ECU
connector C-118 and curtain air bag module (RH)
connector G-04 (MUT-III diagnosis code)
(1) Disconnect the negative battery terminal.

(2) Disconnect connectors C-118 and G-04, and then

reconnect them. For connector G-04, use a
flat-tipped screwdriver to pull out the locking
button at the harness side connector, and then
disconnect the connector.

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

diagnosis code.

Q: Is diagnosis code B1440 set?

YES :

Go to Step 6.

NO :

The procedure is complete. It is assumed
that diagnosis code B1440 set as connector
C-118 or G-04 was engaged improperly.

AC311438 AC

C-118 (Y)

Connector: C-118

Harness side
(front view)

AC311438 AC

C-118 (Y)

Connector: C-118

Harness side
(front view)

AC302575AD

G-04 (B)

Connector: G-04

Harness side
(front view)

Roof centre duct

AC208384AM

G-04
Curtain air bag
module connector

Flat-tip screw
driver

Locking button

G-04
Harness side
connector