Mitsubishi Galant 9G. Manual — part 1463

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-262

DTC B1488: Passenger’s Air Bag OFF Indicator Light Drive Circuit System Fault 2.

CAUTION

If DTC B1488 is set in the SRS-ECU, always diag-
nose the CAN main bus line.

.

CIRCUIT OPERATION

• Power for the passenger’s air bag OFF indicator

light is supplied from the ignition switch (IG1).

• The passenger’s air bag OFF indicator light illu-

minates 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.

.

SRS-ECU

IGNITION
SWITCH (IG1)

JUNCTION
BLOCK

AIR BAG OFF
INDICATOR
LIGHT
(PASSEGER'S SIDE)

RELAY
BOX

JOINT
CONNECTOR (1)

TAILLIGHT
RELAY

FRONT ECU

AIR BAG OFF
INDICATOR LIGHT
DRIVE CIRCUIT

JUNCTION
BLOCK

Air Bag OFF Indicator Light Drive Circuit

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-263

DTC SET CONDITIONS

• This DTC is set under one of the following cases

while the SRS-ECU is monitoring the passen-
ger’s air bag OFF indicator light drive circuit:

• When a short circuit occurs in the passen-

ger’s air bag OFF indicator light drive circuit.

• When a malfunction is detected in the output

transistor inside the SRS-ECU.

However, if the vehicle condition returns to normal,
DTC B1488 will be automatically erased, and the
passenger’s air bag OFF indicator light will go out.

.

TROUBLESHOOTING HINTS

• Damaged wiring harnesses or connectors

• 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.
(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 ).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-264

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 : Check the passenger’s air bag OFF indicator light

drive circuit system (Refer to

P.52B-265

).

NO : There is an intermittent malfunction such as poor

engaged connector(s) or open circuit (Refer to
GROUP 00, How to Use Troubleshooting/Inspection
Service Points

− How to Cope with Intermittent

Malfunctions ).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-265

DTC B1489: Passenger’s Air Bag OFF Indicator Light Drive Circuit System Fault 1 (Light does not
Illuminate).

SRS-ECU

IGNITION
SWITCH (IG1)

JUNCTION
BLOCK

AIR BAG OFF
INDICATOR
LIGHT
(PASSEGER'S SIDE)

RELAY
BOX

JOINT
CONNECTOR (1)

TAILLIGHT
RELAY

FRONT ECU

AIR BAG OFF
INDICATOR LIGHT
DRIVE CIRCUIT

JUNCTION
BLOCK

Air Bag OFF Indicator Light Drive Circuit