Mitsubishi Galant (2004+). Manual — part 1591

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-257

DTC B1487: Passenger’s seat belt warning Light Drive Circuit System Fault 1 (Light does not Switch
Off).

SRS-ECU

IGNITION
SWITCH (IG1)

JUNCTION
BLOCK

SEAT BELT
WARNING
LIGHT
(PASSEGER'S SIDE)

RELAY
BOX

JOINT
CONNECTOR (1)

TAILLIGHT
RELAY

FRONT ECU

JUNCTION
BLOCK

SEAT BELT
WARNING LIGHT
DRIVE CIRCUIT

Seat Belt Warning Light Drive Circuit

AC305233CY

CONNECTOR: C-07

AC305233 AO

CONNECTOR: C-22

C-22 (Y)

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-258

CAUTION

If DTC B1487 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION

• Power for the passenger’s seat belt warning light

is supplied from the ignition switch (IG1).

• The passenger’s seat belt warning light illumi-

nates when the ignition switch is turned to the
"ON" position and goes out after approximately
seven seconds if there is not a malfunction in the
SRS system.

• If a failure occurs in the system, the SRS-ECU

will stop sending that SRS warning light "OFF"
signal, thus causing the combination meter to illu-
minate the SRS warning light.

• The SRS warning light "OFF" signal is not sent to

the combination meter in the cases below, either.
Therefore, the combination meter will illuminate
the SRS warning light.

• The SRS-ECU connector is disconnected.

• The SRS-ECU is not working normally due to

a failure in its power supply lines.

• The wiring harness between the passenger’s

seat belt warning light and the SRS-ECU is
broken.

.

DTC SET CONDITIONS
This DTC will be set if an open circuit has occurred in
the wiring harness between the passenger’s seat
belt warning light and the SRS-ECU. If the vehicle
condition returns to normal, DTC B1487 will be auto-
matically erased, and the passenger’s seat belt
warning light will go out.

.

TROUBLESHOOTING HINTS

• Damaged wiring harnesses or connectors

• Malfunction of the SRS-ECU

• Malfunction of the passenger’s seat belt warning

light

.

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)

AC305362

CONNECTOR: C-121

C-121 (Y)

AD

SRS-ECU

AC305415

CONNECTORS : C-211, C-215

C-211

C-215

AZ

SRS AIR BAG DIAGNOSIS

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SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-259

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-30

."

(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-14

).

STEP 2. 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 the DTC 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.00-6

).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-260

STEP 3. Using scan tool MB991958, read the 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.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOOK (OFF)" position.
Q: Is DTC B1530, B1531, B1532, B1533, B1534, B1535,

B1536, B1537, B1538, B1539, B1540, B1541, B1542,
B1543, B1545 or B1546set?
YES : Carry out the troubleshooting of the passenger’s seat

belt switch system, the occupant classification-ECU
or the occupant classification sensor system. (Refer
to

P.52B-310

<B1530,B1531, B1532, B1533, B1534,

B1535, B1536, B1537, B1538 or B1539>,

P.52B-318

<B1540,B1541, B1542 or B1543> or

P.52B-320

<B1545 or B1546>).

NO : Go to Step 4 .

STEP 4 Using scan tool MB991958, check actuator test.

• Item No.02: Passenger’s seat belt warning light illumination

Q: Does the passenger’s seat belt warning light illuminate

or go out normally?
YES : Go to Step 5 .
NO : Replace the passenger’s seat belt warning light

(Refer to GROUP 52A, Instrument Panel Assembly

P.52A-3

). Then go to Step 6 .

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827