Mitsubishi Galant 9G. Manual — part 1411

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-54

STEP 6. 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 B1401 <1st squib> or B1481 <2nd squib> set?

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

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-55

DTC B1402: Driver's Air Bag Module (1st Squib) System Fault for Power Supply Circuit
(Short-Circuited to Power Supply)
DTC B1482: Driver's Air Bag Module (2nd Squib) System Fault for Power Supply Circuit
(Short-Circuited to Power Supply)

Driver's Air Bag Module (1st and 2nd Squib) Circuit

AIR BAG MODULE
(SQUIB) (DRIVER'S SIDE)

CLOCK
SPRING

AIR BAG DRIVE CIRCUIT

SRS-ECU

CONNECTOR
LOCK SWITCH

: CONNECTOR LOCK SWITCH
CONNECTOR CONNECTED: ON
CONNECTOR DICONNECTED: OFF

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-56

CAUTION

If DTC B1402 <1st squib> or B1482 <2nd squib>
is set in the SRS-ECU, always diagnose 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 SRS
air bag will inflate.

• The ignition signal is input to the air bag module

via the clock spring to inflate the air bag.

.

DTC SET CONDITIONS

This DTC is set if there is abnormal resistance
between the input terminals of the driver's air bag
module (squib). However, if no DTC resets, the SRS
warning light will be switched off (DTC will be
retained).

.

TROUBLESHOOTING HINTS

• Malfunction of the clock spring

• Damaged harness wires and connectors

• Short to the power supply in the driver's air bag

module (squib) harness

• 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)

• MB991865: Dummy resistor

• MB991866: Resister harness

AC305233 AO

CONNECTOR: C-22

C-22 (Y)

AC305362

CONNECTOR: C-121

C-121 (Y)

AD

SRS-ECU

AC305235AP

C-307 (Y)

CONNECTORS: C-305, C-307

CLOCK
SPRING

C-305 (Y)

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

52B-57

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 ).

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 Use Troubleshooting/Inspection
Service Points

− How to Cope with Intermittent

Malfunctions ).

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827