1995 ISUZU TROOPER Workshop Manual

fuel cap display fuel additives oil dipstick tires low beam

Page 1625 of 1928

ISUZU TROOPER 1995 Workshop Manual Supplemental Restraint System 9J-1
SECTION 9J
SUPPLEMENTAL RESTRAINT SYSTEM
(SRS)
WARNING: THIS VEHICLE IS EQUIPPED WITH A SUPPLEMENTAL INFLATABLE RESTRAINT SYSTEM (SRS).
REFER TO WARNING I

Supplemental Restraint System 9J-1
SECTION 9J
SUPPLEMENTAL RESTRAINT SYSTEM
(SRS)
WARNING: THIS VEHICLE IS EQUIPPED WITH A SUPPLEMENTAL INFLATABLE RESTRAINT SYSTEM (SRS).
REFER TO WARNING IN THIS SECTION UNDER "ON-VEHICLE SERVICE" AND THE SRS COMPONENT AND
WIRING LOCATION VIEW IN THIS SECTION BEFORE PERFORMING SERVICE ON OR AROUND SRS
COMPONENTS OR WIRING. FAILURE TO FOLLOW WARNING COULD RESULT IN POSSIBLE AIR BAG
DEPLOYMENT, PERSONAL INJURY, OR OTHERWISE UNNEEDED SRS REPAIRS.
TABLE OF CONTENTS
SUPPLEMENTAL RESTRAINT SYSTEM
(SRS)
SECTION 1 -INTRODUCTION
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 FOR THAT APPLICATION. IF THE CORRECT PART NUMBER 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.
GENERAL DESCRIPTION • • • . • . . . . • . . . . . . . . . • . . . . • . . . . . . . . • . . . . . . . . • . . . . • . • . . 3
Restraint Devices • • • • • • • • • • • • • • • • • • • • • • • • • • .. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 3
'W' System Description • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 4
SRS Component and wiring Location View . . . . . . • . . . . . . . . . . . • . . . . • . . . . . . . . . . • • 5
COMPONENT DESCRIPTION • • . .

. .
• . . • . .
.
• . . • . . . . . . . . . . . . . . . . . • . • . • . . . . • . • • . . 6
DERM ••••••••••••••••••\
••••••••••••••••••\
••••••••••••••••••\
•••••••• ~ • • • • • 6
"AIR BAG"Warnlng Lamp • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • .. • • • • • • • • • • • • 6
Dual Pole Arming Sensor • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 6
Discriminating Sensors • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 6
SRS Coli Assembly • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 7
Inflator Modules • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 7
Steering Column • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 7
Knee Bolster • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 7
DEFINITIONS • • . • . . • • • . • • . • • • • • . • . . • • . • . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . • • • • • • 8
DIAGNOSIS • • • • • • • • • • • • • • • • • • • • • • • • • • • . • • • • • • . • • • • • . . • • . . . . • • • • • . • • • • • • • • • • • 1 0
Diagnostic Trouble Codes • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 0
Scan Tool Diagnostic • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 0
Use of Special Tools • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 0
SRS CONNECTOR BODY FACE VIEWS . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . • . . . . . 11
REPAIRS AND INSPECTION REQUIRED AFTER AN ACCIDENT . . . . . • . . . . . . . . . . . 12
Accident With Deployment-component Replacement and Inspections • • • • • • • • • • • • • • • • • • 12
Accident With or Without Deployment-Component Inspections • • • • • • • • • • • • • • • • • • • • • • • 12
Sensor Replacement Guideline ••••••••• II • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 12
Wiring Damage ••••••••••••••••••\
••• II • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 12
SRS Conector (Plastic Body and Terminal Metal Pin) Damage • • • • • • • • • • • • • • • • • • • • • • • • • 12

Page 1626 of 1928

ISUZU TROOPER 1995 Workshop Manual 9J-2 Supplemental Restraint System
SRS Wire Pigtail Damage ..........................•..........•...............
SRS Wire Damage ...........................................•...............
ON

9J-2 Supplemental Restraint System
SRS Wire Pigtail Damage ..........................•..........•...............
SRS Wire Damage ...........................................•...............
ON-VEHICLE SERVICE ......................................•.•..•..........
Service Precautions ••••.••••••••••••••\
••••••••••••••••••\
••••••••••••••••••\
••
Disabling the SRS ...........................................•...............
Enabling the SRS ................................•..........•....•.....•.... \
Handling/Installation/Diagnosis ..........•.••.......•......•...•........•.•.•\
.•
INFLATOR MODULE HANDLING/SHIPPING/SCRAPPING •....•••••..•.....•••..
Live (Undeployed) Inflator Module ••••••••••••••••••\
••••••••••••••••••\
••••••••••
Inflator Module Shipping Procedures for Live (Undeployed) Inflator Modules •••••••••••••
Deployed Inflator Module ••••••••••••••••••\
••••••••••••••••••\
•••••••••••••••••
Inflator Module Scrapping Procedure ••••••••••••••••••\
••••••••••••••••••\
••••••••
Deployment Outside Vehicle (Driver Inflator Module) ••••••••••••••••••\
••••••••••••••
Deployment Outside Vehicle(Passenger Inflator Module) ••••••••••••••••••\
•••••••••••
Deployment Inside Vehicle(Vehlcle Scrapping Procedure) ••••••••••••••••••\
••••••••••
Deployed Inflator Module Handling ••••••••••••••••••\
••••••••••••••••••\
••••••••••
SPECIAL TOOLS ............................................................ .
SRS Driver/Passenger Load Tool .................•.....••.•••••....•••.\
•••.••••
J-39200 DVM . . . . . . . . . . . . . . • . . . . . . . . . . • . . . . . . . . . . . . . . . • • . • . • . . • . • • . . . . . . . • . .
Scan Tool ...............................................•..•..••.•\
••.....•
J-35616-A Connector Test Adapter Kit ••••••••••••••••••\
••••••••••••••••••\
•••••••
J-41434 SRS Deployment Tool ••••••••••••••••••\
••••••••••••••••••\
•••••••••••••
J-41497 SRS Deployment Fixture ••••••••••••••••••\
••••••••••••••••••\
•••••••••••
12
12
~ 13
13
13 13
13
14
14
14
14
15 16
19
22
24
25
25
26
26
26
26
26
~
•

Page 1627 of 1928

ISUZU TROOPER 1995 Workshop Manual Supplemental Restraint System 9J-3
GENERAL DESCRIPTION
RESTRAINT DEVICES
The Supplemental Restraint System(SRS) helps
supplement the protection offered by the driver and front
passenger seat

Page 1628 of 1928

ISUZU TROOPER 1995 Workshop Manual 9J-4 Supplemental Restraint System
'"""'t::~h-l--"b~RM PASSENGER SlOE HIGH
SYSTEM DESCRIPTION
The main portions of the SRS are the deployment loops ~
and the Diagnostic

9J-4 Supplemental Restraint System
'"""'t::~h-l--"b~RM PASSENGER SlOE HIGH
SYSTEM DESCRIPTION
The main portions of the SRS are the deployment loops ~
and the Diagnostic Energy Reserve Module(DERM).
The main function of the deployment loops is to supply
current through the inflator modules,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 dual pole arming sensor, SRS coil
assembly(
driver side only), inflator modules, LH forward
discriminating sensor and
RH forward discriminating
sensor make up the
deployment loops. The dual pole
arming sensor switches power to the inflator modules on
the high side(power side) of the
deployment loops. Either
of the discriminating sensors can
supply ground to the
inflator modules on the low side (ground side) of the
loops. The inflator modules are only supplied sufficient
current to
deploy when the dual pole arming sensor and
at
least one of the discriminating sensors are closed
simultaneously.
A function of the DERM is to supply the deployment loops
with a 36-Volt Loop Reserve(36VLR) to ensure sufficient
energy to
deploy the air bags if the ignition feed to the
dual pole arming sensor is lost during a frontal crash.
Another function of the DERM is electrical system
diagnostics. The DERM monitors the deployment loops
in conjunction with the resistors in the dual pole arming
sensor, LH
forward discriminating sensor and RH
forward discriminating sensor. These resistors make it
possible for the DERM to detect circuit and component
malfunctions within the deployment loops. The DERM
monitors the
voltage drop across each component within
the
loops during normal non-deployment operation. If
the monitored voltages fall outside of expected limits, the
DERM
will indicate a malfunction through the storage of
a diagnostic trouble code and the illumination of the "AIR
BAG"
warning lamp.

Page 1629 of 1928

ISUZU TROOPER 1995 Workshop Manual (
PASSENGER
INFLATOR
MODULE
RELAY
& FUSE
BOX
(FL-l,FL-2) BATTERY
FORWARD
SENSOR
IRH)
(
(
SRS
COIL
ASSEMBLY
DRIVER
INFLATOR
MODULE
FUSE
BOX
(C-1,C-21,C-22,C-23,C-24)
CONDENSOR
(A

Page 1630 of 1928

ISUZU TROOPER 1995 Workshop Manual 9J-6 Supplemental Restraint System <
COMPONENT DESCRIPTION
DERM
CAUTION: DO NOT OPEN THE DERM CASE FOR
ANY REASON. TOUCHING THE CONNECTOR PINS
OR SOLDERED COMPONENTS MAY CAUSE
ELECTROSTATIC

9J-6 Supplemental Restraint System <
COMPONENT DESCRIPTION
DERM
CAUTION: DO NOT OPEN THE DERM CASE FOR
ANY REASON. TOUCHING THE CONNECTOR PINS
OR SOLDERED COMPONENTS MAY CAUSE
ELECTROSTATIC DISCHARGE DAMAGE. REPAIR
OF A MALFUNCTIONING DERM IS BY
REPLACEMENT ONLY.
The DERM is designed to perform the following functions
in the SRS:
1. Energy Reserve- The DERM maintains two 36-Volt
Loop Reserve(36VLR) energy supplies to provide
deployment energy when the vehicle voltage is low
or lost in a frontal crash.
2. Malfunction Detection-The DERM performs
diagnostic monitoring of SRS electrical components.
3. Malfunction Recording- The DERM provides SRS
diagnostic trouble code information through a scan
tool.
4. Driver Notification- The DERM warns the vehicle
driver of SRS malfunctions by controlling the "AIR
BAG"
warning lamp.
5. Frontal Crash Recording- The DERM records the
SRS status during a frontal crash.
The DERM is connected to the
SRS wiring harness by
a
24-way 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 DERM harness connector is
disconnected. This will cause the "AIR BAG" warning
lamp to come "ON" steady whenever the ignition switch
is at the RUN,BULB
TEST or START positions with the
DERM disconnected.
"AIR BAG"WARNING LAMP
Ignition voltage is applied to the "AIR BAG" warning lamp
when the ignition switch is at the RUN,BULB TEST or
START positions. The DERM 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 DERM operation by flashing SEVEN
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 non-deployment 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.
DUAL POLE ARMING SENSOR ~
The dual pole arming sensor is a protective switch
located in the high side(power side) of the deployment
loops.
The dual pole arming sensor is calibrated to close
at low level velocity changes(lower than the
discriminating sensors).
This ensures that the
inflator modules are connected
directly to the "36 VLR" outputs of the DERM or "Ignition
1" voltage
when any discriminating sensor closes.
The dual pole arming sensor consists of: a sensing
element, two sets of normally open switch contacts,
diagnostic resistors and diodes. The sensing
element
closes
both sets of switch contacts when the velocity of
the
vehicle changes at a rate indicating a potential need
for
deployment.
Two of the diagnostic resistors are connected in parallel
with the switch contacts. This allows a small amount of
current to
flow through each of the deployment loops
during normal, non-deployment operation. This current
flow results in voltage drops across each component in
the
deployment loops. The DERM monitor these voltage
drops to detect circuit or component malfunctions. There
are two
additional diagnostic resistors within the dual
pole
arming sensor which allow the DERM to monitor the
voltage supplied to the high side ofthe deployment loops.
These monitored voltages are used by the diagnostic
logic of the DERM to make a more precise determination
of the
actual deployment loop malfunction. ~
The diodes within the dual pole arming sensor provide
isolation between the "36VLR" outputs of the DERM and
the
vehicle electrical system "Ignition 1" voltage. The
presence of the diodes prevents a direct continuity
measurement through the
dual pole arming sensor
resistors to
terminals"3","4" or "5".
DISCRIMINATING SENSORS
The discriminating sensors are protective switches wired
in parallel on the low side(ground side) of the deployment
loops.
These sensors are calibrated to close with velocity
changes which are severe enough to warrant
deployment.
The discriminating sensors consist of a sensing element
and normally open switch contacts when the vehicle
velocity changes are severe enough to warrant
deployment.
A diagnostic resistor is connected in parallel with the
switch contacts within the
LH forward discriminating
sensor and
RH forward discriminating sensor. These
parallel resistors supply the ground path for the current
passing through the
deployment loops during normal,
non-deployment operation. This current flow results in
voltage drops across each component within the
deployment loops. The DERM monitors these voltage
drops to detect circuit or component malfunctions.
II

Page 1631 of 1928

ISUZU TROOPER 1995 Workshop Manual
SRS COIL ASSEMBLY
The SRS coil assembly consists of two current carrying
coils. They are attached to the steering column and allow
rotation of the steering wheel while maintaining
continu

SRS COIL ASSEMBLY
The SRS coil assembly consists of two current carrying
coils. They are attached to the steering column and allow
rotation of the steering wheel while maintaining
continuous contact of the driver deployment loop to the
driver inflator module.
There is a shorting clip on the yellow
3-way connector
near the base of the steering column which connects the
SRS coil to the SRS wiring harness. The shorting clip
shorts the circuits to the
SRS coil and driver inflator
module when the yellow 3-way connector is
disconnected. The circuit to the driver inflator module is
shorted
in this way to help prevent unwanted deployment
of the air bag when servicing the steering column or other
SRS components.
INFLATOR MODULES
The inflator modules consist of an inflatable bag and an
inflator(a canister of gas-generating material and an
initiating device). When the vehicle is in a frontal crash
of sufficient force to close the dual pole arming sensor
and at least one of the discriminating sensors
simultaneously, current flows through the deployment
loops. Current passing through the initiator ignites the
material
in the inflator module. The gas produced from
this reaction rapidly inflates the air bag.
There is a shorting clip
on the driver inflator module side
of the upper steering column connector which connects
the
SRS coil assembly to the driver inflator module. The
shorting clip shorts across the driver inflator module
circuits when the upper steering column connector is
disconnected. The circuit to the driver inflator module is
shorted
in this way to help prevent unwanted deployment
of the air bag when servicing the driver inflator module,
the steering column
or other SRS components.
There is a shorting clip on the passenger inflator module
connector which connects to the passenger inflator
module jumper. The shorting clip shorts across the
passenger inflator module circuit when the passenger
inflator module connector is disconnected. The circuit to
the passenger inflator module is shorted in this way to
help prevent unwanted deployment of the air bag when
servicing the passenger inflator module, the instrument
panel or other
SRS components.
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. A steering column reinforcement is
also used for additional support.
KNEE BOLSTER
The knee bolsters are used to absorb energy and control
the forward movement of the vehicle's front seat
occupants during a frontal crash, by limiting leg
movement.
Supplemental Restraint System 9J-7

Page 1632 of 1928

ISUZU TROOPER 1995 Workshop Manual 9J-8 Supplemental Restraint System
DEFINITIONS
AIR BAG -An inflatable cloth cushion designed to
deploy in certain frontal crashes. It supplements the
protection offered by the seat belts b

9J-8 Supplemental Restraint System
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 non-periodic
fashion,i.e.no defined time or interval.
B+-Battery voltage, 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 1
0
volts during engine cranking.
BULB
CHECK-The DERM will cause the "AIR BAG"
warning lamp to flash seven times and then go "OFF"
whenever the ignition switch transitions to the RUN
position from any other ignition switch position and no
malfunctions are detected.
"CONTINUOUS MONITORING"-Tests performed by
the DERM on the
SRS every 1 00 milliseconds while
"Ignition
1" voltage is in the normal operating voltage
range at the DERM.
DATA LINK CONNECTOR(DLC)-Formerly "ALDL'', a
connector which allows communication with an
off-board computer, such as a scan
tool.
DATUM LINE-A base line parallel to the plane of the
underbody or frame from which all vertical
measurements originate.
DEPLOY-To inflate the air bag.
DEPLOYMENT
LOOPS - The circuits which supply
current to the inflator modules to deploy the air bag.
DERM -Diagnostic
energy reserve module which
provides reserve energy to the deployment loops and
performs diagnostic monitoring of
all SRS components.
DIAGNOSTIC TROUBLE CODE(DTC) -Formerly
"Code,"a numerical designator used by the DERM to
indicate specific
SRS malfunctions.
DRIVER CURRENT SOURCE-An output of the DERM
which injects current into the driver inflator module circuit
during the "Initiator Assembly Resistance
Test."
DRIVER INFLATOR
MODULE-An assembly located in
the steering wheel hub consisting of an inflatable air bag,
an inflator and an initiator.
DUAL
POLE ARMING SENSOR-A sensor on the high
side(power side) of the deployment loops that is
calibrated to supply voltage to the inflator modules when
the vehicle velocity changes are severe enough to
warrant arming of the air bags in preparation for
deployment.
EEPROM -Electrically Erasable Programmable Read ~
Only Memory. Memory which retains its contents when
power
is removed from the DERM.
FORWARD LH DISCRIMINATING SENSOR-A sensor
on the low side(ground side) of the deployment loops
which is calibrated to ground the inflator modules when
the vehicle velocity changes are severe enough to
warrant deployment of the air bags.
FORWARD RH DISCRIMINATING SENSOR-A sensor
on the low side(ground side) of the deployment loops
which
is calibrated to ground the inflator modules when
the vehicle velocity changes are severe enough
to
warrant deployment of the air bag.
FORWARD LH SENSOR Eng-Room HARNESS-An
assembly of two correct carrying wires which connects
the Forward
LH discriminating sensor to SRS harness.
FORWARD RH SENSOR Eng-Room HARNESS
JUMPER-An assembly of two current carrying wires
which connects the Forward
RH discriminating sensor to
the
SRS harness.
HIGHER PRIORITY FAULT-Each diagnostic trouble
code
is assigned a priority based on the detectability with
other DTCs present. The priority corresponds to the
detectability of the malfunction ONLY, and does NOT
relate to the criticality of the malfunction with respect to ~
deployment or non-deployment under any given
condition.
IGNITION CYCLE -The voltage at the PERM "Ignition
1"
inputs, with ignition switch "ON," is within the normal
operating voltage range for at least ten seconds before
turning ignition switch
"OFF."
IGNITION1
-A battery voltage(B+)circuit which is only
powered with the ignition switch in the RUN,BULB
TEST,or START positions.
INITIATOR-The electrical component inside the inflator
module which, when sufficient current flows, sets off the
chemical reaction that inflates the air bag.
"INITIATOR ASSEMBLY RESISTANCE TEST"-Tests
performed once each ignition cycle when no
malfunctions are detected during "Turn-ON" or
"Continuous Monitoring." This test checks for the correct
DERM configuration for the vehicle, shorts to
"Ignition 1"
in the deployment loops, high resistance or opens in the
"Driver
Side High," "Driver Side Low," "Passenger Side
High"
and "Passenger Side Low" circuits and measures
the resistance of the inflator assembly consisting of: 1)
Initiators, 2) SRS coil assembly(driver side only), 3)
Connectors and associated wiring.
NORMAL OPERATING VOLTAGE RANGE-The ~
voltage measured between the DERM "Ignition 1" ·
terminals and "Ground" terminals is between 7.25 and 16
volts.
•

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