Mitsubishi Galant. Manual — part 597

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM(SRS)

52B-29

DIAGNOSIS

STEP 1. Check SRS-ECU connector C-44 <Vehicles without
SRS side air bag>, C-44, C-45 <Vehicles with SRS side air
bag> for damage. If SRS-ECU connector C-44 <Vehicles
without SRS side air bag>, C-44, C-45 <Vehicles with SRS
side air bag> are damaged, repair or replace them.
Q: Are SRS-ECU connector C-44 <Vehicles without SRS

side air bag>, C-44, C-45 <Vehicles with SRS side air
bag> in good condition?
YES : Replace the SRS-ECU. Refer to

P.52B-65

. Then go

to Step 2.

NO : Repair or replace them.Refer to GROUP 00E,

Harness Connector Inspection

P.00E-2

. Then go to

Step 2.

STEP 2. Check for DTC.

Q: Is DTC 34 output?

YES : There is no action to be taken.
NO : This diagnosis is complete.(If no malfunctions are not

found in all steps, an intermittent malfunction is
suspected. Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points

−

How to

Cope with Intermittent Malfunction.)

DTC 35: SRS-ECU air bag condition monitor detects deployed air bag

DTC SET CONDITIONS

•

This DTC is output after the air bag has
deployed. If this code is output before the air bag
has deployed, the cause is probably a
malfunction inside the SRS-ECU.

TROUBLESHOOTING HINTS

•

Malfunction of the SRS-ECU

DIAGNOSIS
Replace the SRS-ECU. Refer to

P.52B-65

.

Q: Is DTC 35 output?

YES : There is no action to be taken.
NO : This diagnosis is complete.

AC003195AC

CONNECTOR: C-44 <VEHICLES WITHOUT
SRS SIDE AIR BAG>, C-44, C-45
<VEHICLES WITH SRS SIDE AIR BAG>

C-44, C-45

SRS-ECU

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM(SRS)

52B-30

DTC 41: IG1 power circuit system (fuse No.13 circuit)
DTC 42: IG1 power circuit system (fuse No.5 circuit)

CIRCUIT OPERATION

•

The SRS-ECU is powered from the ignition
switch (IG1).

•

The SRS-ECU power is supplied from two
circuits. Even if one circuit is shut off, the air bag
can inflate.

AC002978AB

IG1 Power Circuit (fuse No.13 circuit or No.15 circuit)

AC003195AB

CONNECTOR: C-44

SRS-ECU

CENTER
REINFORCEMENT

AC003201AB

CONNECTOR: C-73, C-77

JUNCTION BLOCK (REAR)

C-73

C-77

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM(SRS)

52B-31

•

The SRS-ECU judges how severe a collision is
by detecting signals from the left and right side
impact sensors and the analog G-sensor. If the
impact is over a predetermined level, the SRS-
ECU outputs an ignition signal. At this time, if the
safing G-sensor is on, the SRS air bag will inflate.

DTC SET CONDITIONS

•

These DTC are output if the voltage between the
IG1 terminals (fuse No.13 or No.5 circuit) and
ground is lower than a predetermined value for a
continuous period of five second or more.
However, if the vehicle condition returns to
normal, DTC numbers 41 or 42 will be
automatically erased, and the SRS warning light
will switch off.

TROUBLESHOOTING HINTS

•

Damaged wiring harnesses or connectors

•

Malfunction of the SRS-ECU

DIAGNOSIS

STEP 1. Check the ignition switch (IG1) line at the SRS-
ECU connector C-44 by backprobing.
(1)Do disconnect the connector C-44.
(2)Connect the negative battery terminal.
(3)Turn the ignition switch to "ON" position.
(4)Measure the voltage between terminal 12 (for DTC 41) or 9

(for DTC 42) and the ground by backprobing.

•

Voltage should be 9 volts or more

Q: Is the voltage 9 volts or more?

YES : Go to Step 3.
NO : Go to Step 2.

STEP 2. Check the harness wires between the ignition
switch (IG1) and SRS-ECU connector C-44.
NOTE: After inspecting intermediate connectors C-73 and C-
77, inspect the wiring harness. If intermediate connectors are
damaged, repair or replace them. Refer to GROUP 00E,
Harness Connector Inspection

P.00E-2

. Then go to Step 5.

Q: Are harness wires between the ignition switch (IG1) and

SRS-ECU connector C-44 in good condition?
YES : Go to Step 5.
NO : Repair them. Then go to Step 5.

AC000367AD

C-44 CONNECTOR HARNESS SIDE VIEW

AC003195AB

CONNECTOR: C-44

SRS-ECU

CENTER
REINFORCEMENT

AC003201AB

CONNECTOR: C-73, C-77

JUNCTION BLOCK (REAR)

C-73

C-77

SRS AIR BAG DIAGNOSIS

TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM(SRS)

52B-32

STEP 3. Check the ground line at the SRS-ECU connector
C-44 by backprobing.
(1)Do disconnect the connector C-44.
(2)Measure the resistance between terminal 3 and ground by

backprobing.

Q: Is the resistance between terminal 3 and ground less

than 2 ohm?
YES : Replace the SRS-ECU Refer to

P.52B-65

. Then go to

Step 5.

NO : Go to Step 4.

STEP 4. Check the harness wires between SRS-ECU
connector C-44 and ground.
Q: Are the harness wires between SRS-ECU connector C-

44 and ground in good condition?
YES : Go to Step 5.
NO : Repair them. Then go to Step 5.

STEP 5. Check for DTC.

Q: Is any of DTC 41 or 42 output?

YES : Replace the SRS-ECU. Refer to

P.52B-65

.

NO : This diagnosis is complete.(If no malfunctions are not

found in all steps, an intermittent malfunction is
suspected. Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points

−

How to

Cope with Intermittent Malfunction.)

AC000368AD

C-44 CONNECTOR HARNESS SIDE VIEW

AC003195AB

CONNECTOR: C-44

SRS-ECU

CENTER
REINFORCEMENT