ISUZU TF SERIES 2004 Owner's Manual
Manufacturer: ISUZU, Model Year: 2004, Model line: TF SERIES, Model: ISUZU TF SERIES 2004Pages: 4264, PDF Size: 72.63 MB
Page 21 of 4264

SUPPLEMENTAL RESTRAINT SYSTEM 9A-1
RESTRAINTS
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
SERVICING
PAGE
Service Precaution ............................................................................................................ 9A- 3
General Description ...................................................................................................... 9A- 4
Restraint Devices ..................................................................................................... 9A- 4
System Description .................................................................................................. 9A- 5
SRS Component And Wiring Location View ............................................................... 9A- 6
Component Description ............................................................................................... 9A- 8
SRS Control Unit ...................................................................................................... 9A- 8
"Air Bag" Warning Lamp.......................................................................................... 9A- 8
SRS Coil Assembly................................................................................................... 9A- 9
Air Bag Assemblies .................................................................................................. 9A- 9
Seat Belt with Pretensioner (If so equipped) ......................................................... 9A- 10
Steering Column ....................................................................................................... 9A- 10
Knee Bolster ............................................................................................................. 9A- 10
Definitions...................................................................................................................... 9A- 10
Diagnosis .......................................................................................................................9A- 12
Diagnostic Trouble Codes ....................................................................................... 9A- 12
Scan Tool Diagnostics ............................................................................................. 9A- 12
Use Of Special Tools ................................................................................................ 9A- 12
SRS Connector Body Face Views................................................................................ 9A- 13
Repairs And Inspections Required After An Accident ............................................... 9A- 14
Accident With Deployment-Component Replacement And Inspections ............. 9A- 14
Accident With or Without Deployment-Component Inspection ........................... 9A- 14
SRS Control Unit Replacement Guidelines ............................................................ 9A- 14
Wiring Damage ......................................................................................................... 9A- 14
SRS Connector (Plastic Body And Terminal Metal Pin) Damage ......................... 9A- 14
SRS Wire Pigtail Damage......................................................................................... 9A- 14
Page 22 of 4264

9A-2 SUPPLEMENTAL RESTRAINT SYSTEM
PAGE
On-Vehicle Service........................................................................................................ 9A- 15
Service Precaution ................................................................................................... 9A- 15
Disable The SRS ....................................................................................................... 9A- 15
Enabling The SRS..................................................................................................... 9A- 15
Handling / Installation / Diagnosis .......................................................................... 9A- 15
Air Bag Assembly Handling / Shipping / Scrapping................................................... 9A- 16
Live (Undeployed) Air Bag Assembly ..................................................................... 9A- 16
Air Bag Assembly Shipping Procedure For Live (Undeployed) Air Bag
Assemblies ................................................................................................................. 9A- 16
Deployed Air Bag Assembly (Driver Side) .............................................................. 9A- 16
Air Bag Assembly Scrapping Procedure ................................................................ 9A- 17
Deployment Outside Vehicle (Driver Air Bag Assembly) ...................................... 9A- 17
Deployment Outside Vehicle (Passenger Air Bag Assembly) .............................. 9A- 20
Deployment Inside Vehicle (Vehicle Scrapping Procedure) ................................. 9A- 22
Deployed Air Bag Assembly Handling .................................................................... 9A- 25
Tech2 Scan Tool............................................................................................................ 9A- 26
Getting Started.......................................................................................................... 9A- 26
Service Precautions for SRS Component Service ..................................................... 9A- 27
Disabling The SRS.................................................................................................... 9A- 27
Enabling The SRS..................................................................................................... 9A- 27
Handling / Installation / Diagnosis .......................................................................... 9A- 27
Inspections Required After An Accident ................................................................ 9A- 27
SRS Connectors ................................................................................................................ 9A- 28
Removal .........................................................................................................................9A- 28
Installation ..................................................................................................................... 9A- 29
SRS Control Unit................................................................................................................9A- 30
Service Precautions ...................................................................................................... 9A- 30
Removal .........................................................................................................................9A- 30
Installation ..................................................................................................................... 9A- 30
Driver Air Bag Assembly ................................................................................................... 9A- 32
Service Precautions ...................................................................................................... 9A- 32
Removal .........................................................................................................................9A- 32
Installation ..................................................................................................................... 9A- 33
Page 23 of 4264

SUPPLEMENTAL RESTRAINT SYSTEM 9A-3
PAGE
Steering Wheel ................................................................................................................... 9A- 35
Service Precautions ...................................................................................................... 9A- 35
Removal .........................................................................................................................9A- 35
Installation ..................................................................................................................... 9A- 36
SRS Coil Assembly ............................................................................................................ 9A- 37
Service Precautions ...................................................................................................... 9A- 37
Removal. ........................................................................................................................9A- 37
Installation. .................................................................................................................... 9A- 38
Steering Column ................................................................................................................9A- 40
Service Precautions ...................................................................................................... 9A- 40
Removal .........................................................................................................................9A- 40
Installation ..................................................................................................................... 9A- 41
Passenger Air Bag Assembly ........................................................................................... 9A- 44
Service Precautions ...................................................................................................... 9A- 44
Removal .........................................................................................................................9A- 44
Installation ..................................................................................................................... 9A- 45
Pretensioner Seat Belt (If so quipped) ............................................................................. 9A- 46
Removal .........................................................................................................................9A- 46
Installation ..................................................................................................................... 9A- 46
Main Data and Specifications ........................................................................................... 9A- 47
Fastener Tightening Specification............................................................................... 9A- 47
Special Tools...................................................................................................................... 9A- 48
5-8840-2421-0 SRS Driver/Passenger Load Tool........................................................ 9A- 48
5-8840-0285-0 DVM........................................................................................................ 9A- 48
Scan Tool .......................................................................................................................9A- 48
5-8840-0385-0 Connector Test Adapter Kit ................................................................. 9A- 49
5-8840-2468-0 SRS Deployment Tool .......................................................................... 9A- 49
5-8840-2420-0 SRS Deployment Fixture ...................................................................... 9A- 49
5-8840-2796-0 SRS Adapter for Load Tool .................................................................. 9A- 49
5-8840-2795-0 SRS Adapter for Deployment Tool ...................................................... 9A- 50
5-8521-0016-0 Steering Wheel remover ...................................................................... 9A- 50
Page 24 of 4264

9A-4 SUPPLEMENTAL RESTRAINT SYSTEM
Service Precaution
WARNING: THIS VEHICLE HAS A SUPPLEMENTAL
RESTRAINT SYSTEM (SRS). REFER TO THE SRS
COMPONENT AND WIRING LOCATION VIEW IN
ORDER TO DETERMINE WHETHER YOU ARE
PERFORMING SERVICE ON OR NEAR THE SRS
COMPONENTS OR THE SRS WIRING. WHEN YOU
ARE PERFORMING SERVICE ON OR NEAR THE
SRS COMPONENTS OR THE SRS WIRING, REFE
R
TO THE SRS SERVICE INFORMATION. FAILURE
TO FOLLOW WARNINGS COULD RESULT IN
POSSIBLE AIR BAG DEPLOYMENT, PERSONAL
INJURY, OR OTHERWISE UNNEEDED SRS
SYSTEM REPAIRS.
CAUTION: Always use the correct fastener in the
proper location. When you replace a fastener, use
ONLY the exact part number for that application.
ISUZU will call out those fasteners that require a
replacement after removal. ISUZU will also call out
the fasteners that require thread lockers or thread
sealant. UNLESS OTHERWISE SPECIFIED, do not
use supplemental coatings (Paints, greases, o
r
other corrosion inhibitors) on threaded fasteners
or fastener joint interfaces. Generally, such
coatings adversely affect the fastener torque and
the joint clamping force, and may damage the
fastener. When you install fasteners, use the
correct tightening sequence and specifications.
Following these instructions can help you avoid
damage to parts and systems.
General Description
CAUTION: When fasteners are removed, always
reinstall them at the same location from which
they were removed. If a fastener needs to be
replaced, use the correct part number fastener fo
r
that application. If the correct part numbe
r
fastener is not available, a fastener of equal size
and strength (or stronger) may be used.
Fasteners that are not reused, and those requiring
thread locking compound will be called out. The
correct torque value must be used when installing
fasteners that require it. If the above conditions
are not followed, parts or system damage could
result.
Restraint Devices
827RW006
Legent
(1) Deployed Air Bag
(2) Knee Bolster
(3) Seat Belt
The Supplemental Restraint System (SRS) helps
supplement the protection offered by the driver and
front passenger seat belts by deploying an air bag
from the center of the steering wheel and from the
front of the passenger side of the instrument panel.
The air bag deploys when the vehicle is involved in a
frontal crash of sufficient force up to 30 degrees off the
centerline of the vehicle. To further absorb the crash
energy there is a knee bolster located beneath the
instrument panel for both the driver and passenger,
and the steering column is collapsible.
827RW005
Page 25 of 4264

SUPPLEMENTAL RESTRAINT SYSTEM 9A-5
System Description
The SRS consists of the SRS control unit, the driver
air bag assembly, the SRS coil assembly, the
passenger air bag assembly and the “AIR BAG”
warning lamp in the instrument cluster. The SRS
control unit, SRS coil assembly (driver side only),
driver air bag assembly, passenger air bag assembly
and connector wire make up the deployment loops.
The function of the deployment loops is to supply
current through air bag assembly, which will cause
deployment of the air bags in the event of a frontal
crash of sufficient force, up to 30 degrees off the
centerline of the vehicle. The air bag assemblies are
only supplied enough current to deploy when the SRS
control unit detects vehicle velocity changes severe
enough to warrant deployment.
The SRS control unit contains a sensing device which
converts vehicle velocity change to an electrical signal.
The electrical signal generated is processed by the
SRS control unit and then compared to a value stored
in memory. When the generated signal exceeds the
stored value, the SRS control unit will cause current to
flow through the air bag assembly deploying the air
bags.
RTW49JLF000101
Page 26 of 4264

9A-6 SUPPLEMENTAL RESTRAINT SYSTEM
SRS Component And Wiring Location View - RHD
RTW49JMF000301
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SUPPLEMENTAL RESTRAINT SYSTEM 9A-7
SRS Component And Wiring Location View - LHD
RTW49JMF000401
Page 28 of 4264

9A-8 SUPPLEMENTAL RESTRAINT SYSTEM
The SRS control unit is connected to the SRS wiring
harness by a 52–pin connector. This harness
connector uses a shorting clip across certain terminals
in the contact area. This shorting clip connects the
“AIR BAG” warning lamp to ground when the SRS
control unit harness connector is disconnected or CPA
(Connector Position Assurance) is not inserted even if
completely connected. This will cause the “AIR BAG”
warning lamp to come “ON” steady whenever the
ignition switch is at the ON or START positions with
the SRS control unit disconnected.
060R300008
Legent
(1) SRS Control Unit
(2) SRS Harness
(3) Connector Position Assurance
Component Description
SRS Control Unit
WARNING: DURING SERVICE PROCEDURES, BE
VERY CAREFUL WHEN HANDLING A SRS
CONTROL UNIT NEVER STRIKE OR JAR THE SRS
CONTORL UNIT. NEVER POWER UP THE SRS
WHEN THE SRS CONTROL UNIT IS NOT RIGIDLY
ATTACHED TO THE VEHICLE. ALL SRS
CONTROL UNIT AND MOUNTING BRACKET
FASTENERS MUST BE CAREFULLY TORQUED
AND THE ARROW MUST BE POINTED TOWARD
THE FRONT OF THE VEHICLE TO ENSURE
PROPER OPERATION OF THE SRS. THE SRS
CONTROL UNIT COULD BE ACTIVATED WHEN
POWERED WHILE NOT RIGIDLY ATTACHED TO
THE VEHICLE WHICH COULD CAUSE
DEPLOYMENT AND RESULT IN PERSONAL
INJURY.
The SRS control unit is designed to perform the
following functions in the SRS:
1. Energy Reserve — The SRS control unit maintains
24–
Volt Loop Reserve (24VLR) energy supply to
provide deployment energy when ignition voltage is
lost in a frontal crash.
2. Frontal Crash Detection — The SRS control uni
t
monitors vehicle velocity changes to detect frontal
crashes which are severe enough to warran
t
deployment.
3. Air Bag Deployment — When a frontal crash o
f
sufficient force is detected, the SRS control unit
will cause enough current to flow through the air
bag assembly to deploy the air bag.
4. Malfunction Detection —The SRS control uni
t
performs diagnostic monitoring of SRS electrical
components and sets a diagnostic trouble code
when a malfunction is detected.
5. Frontal Crash Recording — The SRS control uni
t
records information regarding SRS status during
frontal crash.
6. Malfunction Diagnosis —The SRS control uni
t
displays SRS diagnostic trouble codes and system
status information through the use of a scan tool.
7. Driver Notification — The SRS control unit warns
the vehicle driver of SRS malfunctions b
y
controlling the “Air Bag” warning lamp.
“Air Bag” Warning Lamp
Ignition voltage is applied to the “AIR BAG” warning
lamp when the ignition switch is at the ON or START
positions. The SRS control unit controls the lamp by
providing ground with a lamp driver. The “AIR BAG”
warning lamp is used in the SRS to do the following:
1.
Verify lamp and SRS control unit operation by
flashing SEVEN (7) times when the ignition switch
is first turned “ON”.
2. Warn the vehicle driver of SRS electrical system
malfunctions which could potentially affect the
operation of the SRS. These malfunctions could
result in nondeployment in case of a frontal crash
or deployment for conditions less severe than
intended.
The “AIR BAG “ warning lamp is the key to driver
notification of SRS malfunctions. For proper lamp
operation, refer to the “SRS Diagnostic System Check”
in this section.
Page 29 of 4264

SUPPLEMENTAL RESTRAINT SYSTEM 9A-9
060R300007
SRS Coil Assembly
The SRS coil assembly consists of two current
carrying coils. This is attached to the steering column
and allow rotation of the steering wheel while
maintaining continuous contact of the driver
deployment loop to the driver air bag assembly.
There is a shorting clip on the yellow connector near
the base of steering column which connects the SRS
coil to the SRS wiring harness.
The shorting clip shorts to the SRS coil and driver air
bag assembly when the yellow connector is
disconnected. The circuit to the driver air bag
assembly is shorted in this way to help prevent
unwanted deployment of the air bag when servicing
the steering column or other SRS components.
060R300047
Air Bag Assemblies
The air bag assembly consist of an inflatable air bag
assembly and an inflator. When the vehicle is in a
frontal crash of sufficient force.
The SRS control unit causes current flow through the
deployment loops. Current passing through the inflator
ignites the material in the air bag assembly. The gas
produced from this reaction rapidly inflates the air bag
assembly.
There is a shorting clip on the driver air bag assembly
connector which connects the SRS coil assembly. The
shorting clip shorts across the driver air bag assembly
circuits when driver air bag assembly connector is
disconnected.
The circuit to the driver air bag assembly is shorted in
this way to help prevent unwanted deployment of the
air bag when servicing the driver air bag assembly, the
steering column or other SRS components.
060R300012
There is a shorting clip on the passenger air bag
assembly connector which connects to the SRS
harness. The shorting clip shorts across the
passenger air bag assembly circuit when the
passenger air bag assembly connector is
disconnected. The circuit to the passenger air bag
assembly is shorted in this way to help prevent
unwanted deployment of the air bag when servicing
the passenger air bag assembly, the instrument panel
or other SRS components.
Page 30 of 4264

9A-10 SUPPLEMENTAL RESTRAINT SYSTEM
060R300013
Seat Belt with Pretensioner (If so
equipped)
The seat belt comprises a seat belt and a cylinder (a
cylinder filled with powder and an ignition device). In
cases of frontal collision which cause a shock
exceeding a specified level, the controller lets current
flow to the inflation circuit. The current ignites the
cylinder of the seat belt, producing gas. The gas helps
tighten the seat belt to restrain firmly the driver’s upper
half in his seat.
RTW49JSH000201
Steering Column
The steering column absorbs energy and is designed
to compress in a frontal crash to decrease the chance
of injury to the driver.
060R300038
Knee Bolster
The knee bolsters are used to absorb energy to
protect knees and control the forward movement of
the vehicle's front seat occupants during a frontal
crash, by limiting leg movement.
Definitions
Air Bag
An inflatable cloth cushion designed to deploy in
certain frontal crashes. It supplements the protection
offered by the seat belts by distributing the impact load
more evenly over the vehicle occupant's head and
torso.
Asynchronous
Performed in a nonperiodic fashion, (i.e., no defined
time or interval).
B+
Battery voltage, (B+) The voltage available at the
battery at the time of the indicated measurement.
With the key “ON” and the engine not running, the
system voltage will likely be between 12 and 12.5
volts. At idle, the voltage may be 14 to 16 volts. The
voltage could be as low as 10 volts during engine
cranking.
Bulb Check
The SRS control unit will cause the “AIR BAG” warning
lamp to flash seven times and then go “OFF”
whenever the ignition switch transitions to the ON
position from any other ignition switch position and no
malfunctions are detected.