Mitsubishi Outlander GS45X. Manual — part 1438

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-247

DTC B1C39: Driver's Seat Belt Pre-tensioner (Squib) System (Shorted to Squib Circuit Power Supply)

CAUTION

If DTC B1C39 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT 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 pre-tensioner will deploy.

.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance
between the input terminals of the driver's seat belt
pre-tensioner (squib).

.

TROUBLESHOOTING HITS

• Damaged wiring harnesses or connectors

• Short to the power supply in the driver's seat belt

pre-tensioner (squib) harness

• Malfunction of the SRS-ECU

: CONNECTOR COUPLED: ON
CONNECTOR UNCOUPLED: OFF

NOTE

Seat Belt Pre-Tensioner (Driver's side) (Squib) Circuit

SRS-ECU

SEAT BELT
PRE-TENSIONER
(LH)

CONNECTOR
LOCK SWITCH

CONNECTOR
LOCK
SWITCH

AC901076

C-27 (Y)

AC

Connector: C-27

AC901080AD

Connector: D-121

D-121 (B)

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

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DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: M.U.T.-III USB Cable

• MB991910: M.U.T.-III Main Harness A (Vehicles with

CAN Communication System)

• MB991865: Dummy resistor

• MB991884: Resister harness

STEP 1. Using scan tool MB991958, diagnose the CAN bus
line.

CAUTION

To prevent damage to scan tool MB991958, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958. Refer to "How to connect the

scan tool

P.52B-28

."

(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

P.54C-17

).

ZC501967

AC404789

AC701411AB

MB991824

MB991827

MB991910

Data link
connector

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

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STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "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 : Go to Step 6.

STEP 3. Check the driver's seat belt pre-tensioner. (Using
scan tool MB991958, read the diagnostic trouble code.)
(1) Disconnect the negative battery terminal.
(2) Disconnect driver's seat belt pre-tensioner connector

D-121. Use a flat-tipped screwdriver to unlock the locking
button at the harness side connector by withdrawing it
toward you in two stages, and then disconnect the
connector.

(3) Connect special tool MB991865 to special tool MB991884.
(4) Connect special tool MB991884 to the D-121 harness side

connector.

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

diagnostic trouble code.

Q: Is DTC B1C39 set?

YES : Go to Step 4.
NO : Replace the driver's seat belt with pre-tensioner.

(Refer to

P.52B-457

). Then go to Step 6.

ZC501967

AC404789

AC701411AB

MB991824

MB991827

MB991910

Data link
connector

AC507550AE

Seat belt
pre-tensioner

Harness side
connector

Locking
button

Flat-tipped
screwdriver

AC301553 BE

Harness side
connector

MB991865

(Dummy resistor: 3 )

MB991884

(Resistor harness)

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

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STEP 4. Check the driver's seat belt pre-tensioner circuit.
Measure the voltage at the SRS-ECU connector C-27.
(1) Disconnect the negative battery terminal.
(2) While pushing the part "A" indicated in the figure of the

harness side connector, turn the lock lever to the direction
of the arrow to release the lock lever, and disconnect the
C-27 SRS-ECU connector.

DANGER

To prevent the seat belt pre-tensioner from deploying
unintentionally, disconnect the driver’s seat belt
pre-tensioner connector D-121 to short the squib cir-
cuit.

(3) Disconnect driver's seat belt pre-tensioner connector

D-121. Use a flat-tipped screwdriver to unlock the locking
button at the harness side connector by withdrawing it
toward you in two stages, and then disconnect the
connector.

CAUTION

Insert an insulator such as a cable tie to a depth of 4mm
(0.16 inch) or more, otherwise the short spring will not be
released.
(4) Insert a cable tie [3 mm (0.12 inch) wide, 0.5 mm (0.02 inch)

thick] between terminals 45, 46 and the short spring to
release the short spring.

(5) Connect the negative battery terminal.
(6) Ignition switch: "ON".

AC507645

A

AC

Lock lever

AC507550AE

Seat belt
pre-tensioner

Harness side
connector

Locking
button

Flat-tipped
screwdriver

AC507303AN

A

A

C-27 Harness side
connector (front view)

Section
A - A

Cable tie

Short spring

4 mm or more

Terminal