Mitsubishi Galant 9G. Manual - part 1483

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-342

INSPECTION PROCEDURE 3: When the Ignition Key is Turned to "ON" (Engine Stopped), the SRS
Warning Light does not Illuminate. INSPECTION PROCEDURE 4: The SRS Warning Light Remains
Illuminated after the Engine is Started.

AC401937

CPU

COMBINATION
METER

JOINT
CONNECTOR (3)

DATA LINK
CONNECTOR

SRS-ECU

BATTERY

IGNITION SWITCH (IG1)

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-343

TECHNICAL DESCRIPTION (COMMENT)

• The SRS-ECU sends the SRS warning light sig-

nal to the combination meter via the CAN com-
munication.

• This may be caused by faults in the CAN bus line,

the combination meter or the SRS-ECU.

TROUBLESHOOTING HINTS (THE MOST
LIKELY CAUSES FOR THIS CASE:)

• Damaged wiring harness or connector

• Combination meter defect

• Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

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

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A (Vehicles with CAN

communication system)

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.
Use scan tool MB991958 to diagnose the CAN bus lines.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.

Q: Is the check result satisfactory?

YES : Go to Step 2.
NO : Repair the CAN bus lines (Refer to GROUP 54C,

Diagnosis-Can Bus Diagnostic Chart ). Repair the
CAN bus lines, and then go to Step 2.

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-344

STEP 2. Using scan tool MB991958, read the combination
meter diagnostic trouble code.

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.
Use scan tool MB991958 to check whether combination meter
DTC U1112 has been set.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Check whether combination meter DTC U1112 has been

set.

Q: Is combination meter DTC U1112 set?

YES : Replace the SRS-ECU.
NO : Replace the combination meter.

DATA LIST REFERENCE TABLE

M1524003500038

The following items can be read by the scan tool
from the SRS-ECU input data.

AC305412

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

No.

DATA LIST ITEM

CHECK
CONDITIONS

NORMAL CONDITIONS

Failure continuation time 1

Always

Maximum time to be stored: 9999
minutes (approximately seven
days)

Failure continuation time 2

Always

Seat position

Slide the seat from
the back-end position
to the front-end
position.

Rear/Front

Passenger seat Airbag Ignition

Do not apply any load
to the passenger
seat.

Permission/Prohibition

Driving seatbelt (Buckle SW1)

Wear the driver
seatbelt.

Unfastened/Fastened

Driving seatbelt (Buckle SW2)

Undo the driver
seatbelt.

Fastened/Unfastened

Passenger seatbelt (Buckle
SW1)

Wear the passenger
seatbelt.

Unfastened/Fastened

Passenger seatbelt (Buckle
SW2)

Undo the passenger
seatbelt.

Fastened/Unfastened

Elimination times

Always

Maximum time to be stored: 255
days

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-345

NOTE:

•

: indicates the duration from the occurrence of failure to the first ignition signal output.

•

: indicates the duration from the first collision judgment or non-ignition judgment to the present.

ACTUATOR TEST REFERENCE TABLE

M1524003600035

The scan tool activates the following actuators for
testing.

FAIL-SAFE FUNCTION

M1524003700021

If the SRS-ECU determines that the following parts
are defective, the SRS-ECU operates the SRS warn-
ing light and controls as follows.

• If the seat belt switch is defective, the SRS-ECU

determines that the seat belt is fastened and con-
trols the seat belt with pre-tensioner.

• If the seat slide sensor is defective, the SRS-ECU

determines that the seat is in its backward posi-
tion and controls the air bag.

• If the occupant classification sensor or the occu-

pant classification-ECU is defective, the
SRS-ECU determines that the occupant classifi-
cation is class 2 (The occupant classification sen-
sor detects 30 kg or more.) and controls the air
bag and the passenger’s air bag OFF indicator
light.

ACCURACY TESTING OF OCCUPANT CLASSIFICATION SENSOR

M1524025800015

The scan tool can be used to perform the next func-
tion.

• Seat Weight Sensor Accuacy Check

• Zero-calibration

OCSS Occupant Classification

Apply a load to the
passenger seat.

Class 0/Class 1/Class 2/Not Clear/

−

OCSS Occupant Weight

kg/Unkown

OCSS Parts Number

Always

−

No.

DATA LIST ITEM

CHECK
CONDITIONS

NORMAL CONDITIONS

MUT-III SCAN TOOL
DISPLAY

ITEM NO.

ITEM

PARTS TO BE ACTIVATED

SRS Warning Lamp

The SRS warning light illuminates.

CAN output

Passenger Seat belt
Warning Lamp

Passenger’s seat belt warning light
illumination

SRS-ECU output

Passenger SRS OFF
Lamp

Passenger’s air bag OFF indicator
light illumination

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