Isuzu N-Series. Manual - part 1181

SRS 9B-7

About Terms

SRS airbag
This is expansion-type cloth cushion designed to be de-
ployed on frontal collision above a certain impact. Airbag
reduces an impact on occupant’s head and trunk and
supplements the protection by seat belts.

B+
Battery voltage (B+)

Warning lamp bulb check
When no function fault is detected after starter switch is
turned to “ON” position, “SRS” warning lamp blinks sev-
en times and goes off.

“Constant diagnosis”
Fault diagnosis is constantly performed by SRS control
unit as long as “Ignition A” voltage is within the range of
specified operating voltage of the unit.

Diagnostic connector (16-pin)
This is a connector to communicate with Tech 2.

Deployment
This means expansion of airbag.

Deployment circuit
This is a circuit which sends current to airbag assembly
to deploy airbag.

Diagnostic trouble code (DTC)
This is number used by SRS control unit to identify the
trouble in SRS function. (Self-diagnosis code)

Current supply for driver’s seat
This is output of SRS control unit to send current to driv-
er’s airbag assembly circuit during “Ignition device resis-
tance test”.

EEPROM
This is an electrically erasable programmable read only
memory. This is a memory which can store contents
without power on SRS control unit.

Ignition device
This is electric ignition device to combust gas generating
agent of inflator.

Specified operating voltage range
This is voltage range from 18 to 32 V measured between
“Ignition A” terminal and “Ground” terminal of SRS con-
trol unit.

Tech 2
This is diagnostic equipment to read diagnostic informa-
tion from SRS control unit via diagnostic connector.

SRS control unit
This supplies backup current to deployment circuit and
deploy airbag if necessary. Also it diagnoses all the SRS
parts.

Serial data
This is Tech 2 information which indicates SRS operat-
ing condition.

SRS
This means supplemental restraint system.

SRS coil assembly
This is device to maintain successive continuity on de-
ployment circuit for SRS airbag and allow steering wheel
to rotate.

SRS harness
These are harnesses and connectors to connect SRS
parts electrically.

Initial diagnosis
These are tests for SRS, performed by SRS control unit
on the following conditions: after starter switch is “ON”,
immediately after “Ignition A” voltage is energized by
SRS control unit, or before “Constant diagnosis”. (per-
formed within 6 seconds after starter switch is “ON”)

9B-8 SRS

SRS Control Unit

Precautions on Service Work

WARNING:

DURING SERVICE WORK, BE CAREFUL NOT TO
TAP OR SHAKE THE SRS CONTROL UNIT. ALSO,
FAILURE TO INSTALL THE SRS CONTROL UNIT TO
VEHICLE PROPERLY MAY LEAD TO MALFUNC-
TION OF THE UNIT WHEN THE STARTER SWITCH IS
TURNED TO ON. THIS MAY RESULT IN INJURY DUE
TO SUDDEN DEPLOYMENT OF SRS AIRBAG.

Removal

1. Stop the function of SRS. (Refer to “Procedure to

stop the function of SRS” in “SRS System Assem-
bly”.)

2. Remove the two bolts and protector.
3. Disconnect the SRS control unit harness connec-

tor.

4. Remove the four mounting bolts of SRS control

unit and remove SRS control unit.

Legend

1. Protector

Installation

1. Install the SRS control unit to steering support

bracket and tighten the mounting bolt to the speci-
fied torque.

Tighten:
Bolt to 9.8 

± 2.9 N⋅m (1.0 ± 0.3 kg⋅m / 7.2 ± 2.1 lb⋅ft)

2. Connect the SRS control unit harness connector.
3. Install the protector to steering support bracket and

tighten the mounting bolt to the specified torque.

Tighten:
Bolt to 8.0 

± 2.0 N⋅m (0.8 ± 0.2 kg⋅m / 5.9 ± 1.5 lb⋅ft)

4. Resume the function of SRS. (Refer to “Procedure

to resume the function of SRS” in “SRS System As-
sembly”.)

Legend

1. SRS control unit

1

N9A0024E

1

N9A0025E

SRS 9B-9

SRS Airbag Assembly

Precautions on Service Work

Procedure to Carry Undeployed SRS Airbag Assem-
bly
Take extreme care when handling and storing unde-
ployed airbag. In case of deployment of SRS airbag, ob-
ject on the surface of SRS airbag may be blown away
due to sudden generation of gas.

WARNING:

WHEN CARRYING UNDEPLOYED SRS AIRBAG AS-
SEMBLY, BE SURE TO TURN THE TRIM COVER TO-
WARD OUTSIDE TO REDUCE THE POSSIBILITY OF
INJURY IN CASE OF AIRBAG DEPLOYMENT. ALSO,
NEVER GRASP THE HARNESS OR CONNECTOR
OF SRS AIRBAG TO CARRY IT.

Legend

1. Trim cover

Handling of Deployed Airbag Assembly
After SRS airbag is deployed, do not touch within 30
minutes because a burn may occur due to its heat.
When handling deployed SRS airbag, wear gloves and
safety goggles to protect from generated irritant and
heat.

Disposal Procedure of SRS Airbag
In some cases, it may be necessary to dispose unde-
ployed SRS airbag during usable life of the vehicle.
Perform the proper disposal procedure of undeployed
airbag.
To dispose undeployed SRS airbag, the airbag must be
deployed compulsorily beforehand. Undeployed airbag
cannot be disposed as it is.

WARNING:

FAILURE TO FOLLOW THE PROPER DISPOSAL
PROCEDURE MAY CAUSE INJURY DUE TO DE-
PLOYMENT OF SRS AIRBAG. UNDEPLOYED AIR-
BAG MUST BE DEPLOYED BEFORE DISPOSAL.

Legend

1. When carrying undeployed airbag, turn the trim

cover toward outside.

2. When placing undeployed airbag, be sure to turn

the trim cover upward.

Precautions on Airbag Deployment Procedure for
Disposal
Failure to perform the correct procedure leads to serious
accident due to airbag malfunction during work. Be sure
to perform the correct procedure.

1. Turn the starter switch to OFF (LOCK), disconnect

the (

−) terminal of battery and wait for 15 seconds

before starting work.
(Because airbag can be activated by backup power
even if battery power is cut off at collision.)

2. Never disassemble airbag.
3. Do not make an impact on airbag or put it close to

magnet.
(Because it may cause airbag malfunction. It is
very dangerous.)

1

N9A0026E

2

1

N9A0027E

9B-10 SRS

4. Place airbag with trim cover facing upward. Never

put any object on it.

5. Do not put airbag on the floor directly to perform

deployment.
(Because it may be blown away for 2 to 3 meters
(7 to 10 feet) due to impact.)

6. If installing airbag to vise or tire, fix it securely.
7. Place battery more than 10 m (33 ft) away from

airbag.

8. Before disconnecting the harness of airbag, touch

the metal parts of vehicle for body grounding of
worker.
(To prevent malfunction due to static electricity)

9. Do not stand in front of airbag when handling har-

ness.

10. Let nearby personnel know about deployment be-

cause loud sound occurs. Also, put blanket on
steering wheel or tire, or close the windows to re-
duce deployment sound as possible if deploying in
vehicle.

11. Perform the work in well-ventilated area since de-

ployment emits smoke.
(For indoor deployment, do not perform near fire-
alarm, smoke-alarm, or under fluorescent.)

12. Take care not to inhale smoke emitted on deploy-

ment.

13. Put cover on vehicle since glasses of vehicle may

be broken on deployment if they are damaged.

14. Directly after airbag is deployed, leave it for 30 min-

utes since it is very hot.

15. Do not pour water etc. to the deployed airbag.
16. Wear protective tools such as safety goggles,

gloves, etc. during work and wash them thoroughly
after work.

17. Do not reuse removed airbag to equip other vehicle

with.
(Because operating characteristics depend on ve-
hicle models.)

There are two methods to deploy undeployed airbag as-
sembly: out-vehicle deployment and in-vehicle deploy-
ment.

Out-vehicle Deployment (Using Deployment Mount-
ing tool)

WARNING:

FAILURE TO FOLLOW THE PROPER DISPOSAL
PROCEDURE MAY CAUSE INJURY DUE TO DE-
PLOYMENT OF SRS AIRBAG. UNDEPLOYED AIR-
BAG MUST BE DEPLOYED BEFORE DISPOSAL.

Deployment procedure must be observed to deploy the
undeployed airbag assembly out of vehicle.
During deployment procedure, always wear safety gog-
gles until disposing deployed airbag assembly. Before
performing deployment procedure, read carefully de-
scription to understand the service work of SRS and the
proper handling of airbag assembly.

Prepare SRS airbag deployment tool (5-8840-2468-0),
2-pole extension cord, SRS deployment mounting tool
(5-8840-2420-0), vise and tire for the procedure. Do not
perform the procedure without these tools.

WARNING:

SRS AIRBAG ASSEMBLY DEPLOYS IMMEDIATELY
AFTER CONNECTING POWER SUPPLY TO SRS DE-
PLOYMENT HARNESS. THEREFORE, BE SURE TO
CONNECT POWER SUPPLY WITH THE HARNESS IN
THE END OF THE DEPLOYMENT PROCEDURE OF
SRS AIRBAG ASSEMBLY. FAILURE TO FOLLOW
THIS MAY CAUSE INJURY. ALSO, ALWAYS WEAR
SAFETY GOGGLES DURING DEPLOYMENT AND
DISPOSAL PROCEDURES.

1. Turn the starter switch to “LOCK”, remove the key

and wear safety goggles.

2. Inspect SRS airbag deployment tool (5-8840-

2468-0) and 2-pole extension cord for damage. If
the harness or extension cord is damaged, use
new one.

3. Remove the SRS airbag assembly from the vehi-

cle. Refer to “Removal” in “SRS Airbag Assembly”.

4. Make open space (diameter of more than 2

meters) for deployment of SRS airbag assembly
mounted to deployment mounting tool. Outdoor
paved place in which safety is secured is recom-
mended, however well-ventilated service work
place is also available. Besides, make sure that
there are no objects or flammable materials in de-
ployment area. (For indoor deployment, do not per-
form near fire-alarm, smoke-alarm, or under
fluorescent.)

5. Install SRS airbag mounting tool (5-8840-2420-0)

to vise to stabilize the tool during deployment.

N9A0081E