Mitsubishi Evolution X. Manual — part 696

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-231

STEP 4. Check the driver's seat belt pre-tensioner.
(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-36 SRS-ECU connector.

(3) Disconnect driver's seat belt pre-tensioner connector D-25.

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.

(4) Connect special tool MB991865 to special tool MB991884.
(5) Connect special tool MB991884 to the D-25 harness side

connector.

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

diagnostic trouble code.

Q: Is DTC B1C3B set?

YES : Go to Step 5.
NO : Replace the driver's seat with belt pre-tensioner

(Refer to

P.52B-413

). Then go to Step 7.

AC507645

A

AC

Lock lever

AC608959

AC

Pre-tensioner

Harness side
connector

Locking
button

Flat-tipped
screwdriver

AC301553CB

D-25 Harness side
connector

MB991884

(Resistor harness)

MB991865

(Dummy resistor: 3 )

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-232

STEP 5. Check the driver’s seat belt pre-tensioner circuit.
Measure the resistance at the SRS-ECU connector C-36.
(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-36 SRS-ECU connector.

DANGER

To prevent the seat belt pre-tensioner from deploying
unintentionally, disconnect the driver’s seat belt
pre-tensioner connector D-25 to short the squib cir-
cuit.

(3) Disconnect driver's seat belt pre-tensioner connector D-25.

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.

AC507645

A

AC

Lock lever

AC608959

AC

Pre-tensioner

Harness side
connector

Locking
button

Flat-tipped
screwdriver

AC507303 CC

A

A

C-36 Harness side
connector (front view)

Section
A - A

Cable tie

Short spring

4 mm (0.16 inch) or more

Terminal

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-233

(5) Check for continuity between C-36 harness side connector

terminals 45 and 46.
It should be an open circuit.

Q: Is it open circuit?

YES : Erase the diagnostic trouble code memory, and check

the diagnostic trouble code. If DTC B1C3B sets,
replace the SRS-ECU (Refer to

P.52B-383

). Then go

to Step 7.

NO : Go to Step 6.

STEP 6. Check the harness for short circuit between
SRS-ECU connector C-36 (terminal No.45 and 46) and
driver’s seat belt pre-tensioner connector D-25 (terminal
No.1 and 2).
Q: Are harness wires between SRS-ECU connector C-36

(terminal No.45 and 46) and driver’s seat belt
pre-tensioner connector D-25 (terminal No.1 and 2) in
good condition?
YES : Go to Step 7.
NO : Replace the harness wires between SRS-ECU

connector C-36 and driver’s seat belt pre-tensioner
connector D-25. Then go to Step 7.

STEP 7. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC B1C3B set?

YES : Return to Step 1.
NO : The procedure is complete.

AC608812

C-36 Harness side
connector (front view)

GJ

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-234

DTC B1C47: Front Passenger's pre-tensioner (squib) system (shorted to squib circuit Ground)

CAUTION

If DTC B1C47 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 passenger's seat
belt pre-tensioner (squib).

.

TROUBLESHOOTING HITS

• Damaged wiring harnesses or connectors

• Short to the ground in the passenger's seat belt

pre-tensioner (squib) harness

• Malfunction of the SRS-ECU

SEAT BELT
PRE-TENSIONER (RH)

CONNECTOR
LOCK
SWITCH

CONNECTOR
LOCK SWITCH

SRS-ECU

Seat Belt Pre-Tensioner (RH) (Squib) Circuit

AC708951AD

Connector: C-36

C-36 (Y)

AC708954 AH

Connector: D-40

D-40 (B)