wheel ISUZU TROOPER 1995 Workshop Manual

------------- -
CHASSIS ELECTRICAL 8-279
Step Operation Item to be checked Item of Remarks
malfunction
34 Close right rear door.
Insert key into key cylinder of right
Check to see if indicator light stays 35 front door and turn it in lock on steadily. B direction.
36 Wait about 10 seconds. Check
to see if indicator light goes c Activate alarm device. off after about 10 seconds.
37 Unlock right front door with lock-Check to see if alarm operates. D Only right front door ing knob.
is unlocked.
Insert
key into key cylinder of right With
key at unlock
position, check to see 38 front door and turn it in unlock Check to see if alarm stops E if alarm stops. (With
direction.
all doors unlocked.)
Check to see if indicator light flashes.
39 Open right front door.
A
Check to
see if dome light and
courtesy light come on.
40 Close right front door.
Check to
see if indicator light stays 41 Lock right front door with key.
on steadily. B
42 Wait about 10 seconds. Check
to see if indicator light goes c Activate alarm device. off after about 10 seconds.
43 Unlock right front door with key. Check
to see if alarm does not F operate.
Check to
see if indicator light stays 44 Lock right front door with key.
on steadily. B
45 Wait about 10 seconds. Check
to see if indicator light goes c Activate alarm device. off after about 10 seconds.
46 Open engine hood with engine
Check to see if alarm operates. I hood release handle.
47 Insert key into starter switch and
Check to see if alarm stops. J turn it to "ACC" position.
NOTE: When the connector of the anti-theft controller is disconnected, the starter is inoperative.
In the checking of short wheel base model, Step Nos. 16 through 21 and Step Nos. 31 through 36
are omitted.

8-382 CHASSIS ELECTRICAL
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)-AIR BAG
The system consists of the starter switch, Diagnostic Energy Reserve Module (OERM), dual pole arming
sensor,
SRS coil assembly, inflator module (driver & passenger), forward sensor and warning light.
SRS is mainly comprised of the deployment loop and the DERM.
The main function of the deployment loop is to flow current into the inflator modules inside the steering
wheel (driver side) and the passenger side instrument panel (passenger side) to inflate the air bag. The
forward sensor
(LH and /or RH) gets activated by a shock caused by collision during running of a vehicle, the
current
from the battery flows into the inflator modules through dual pole arming sensor, so that the air bag
is
inflated.
The DERM supplies the current to the deployment loop to ensure that the air bag is inflated, if the power
circuit between battery and deployment loop is cut off by the shock of collision.
In
addition, the DERM monitors a voltage drops between components, and if the voltage drops below the
specified
value, the driver is alerted by the "AIR BAG" warning light in meter assembly.
Refer to Section 9J "SUPPLEMENTAL RESTRAINT SYSTEM (SRS)-AIR BAG" for details.
OPERATION OF THE CIRCUIT
DRIVER
INFLATOR MODULE
FOWARD
SENSOR-LH
D
D
STARTER SW
D
1
DUAL POLE ARMING SENSOR
PASSENGER
INFLATOR
MODULE
FORWARD
SENSOR-RH
NOTE: Arrow marks "c::::>" indicate the direction of current
Fig. 8-438
•

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
belts by deploying an air bag from the
center of the steering
wheel and from the top of the right
side of the instrument
panel.
~ Deployed Air Bag
~ Knee Bolster
~ Seat Belt
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.

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

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.
•

PASSENGER CURRENT SOURCE -An output of the
DERM which injects current into the passenger inflator
module circuit during the
~Initiator Assembly Resistance
'--"" Test."
PASSENGER INFLATOR MODULE -An assembly
located in the right side of the 1/P consisting of an
inflatable bag, an inflator and an initiator.
SCAN TOOL -An off-board computer used to read
diagnostic information from on-board computers via the
data
link connector.
SERIAL DATA -Information representing the status of
the
SRS.
SRS
-Supplemental Restraint System.
SRS COIL ASSEMBLY-An assembly of two current­
carrying coils in the driver deployment loop that allows
the rotation of the steering wheel while maintaining the
continuous contact
of the driver deployment loop to the
driver inflator module.
SRS WIRING HARNESS-The wires and connectors
that electrically connect the components in the
SRS.
1 Supplemental Restraint System 9J-9
"10 MINUTE LOOP TEST' -Portions of the "Initiator
Assembly Resistance Test" are repeated every ten
minutes during an ignition cycle. These are the check for
shorts to
"Ignition 1" in the deployment loops and the
check for an open discriminating sensor interconnect
circuit.
''TURN-ON" -Test which the DERM performs on the
SRS once during each ignition cycle immediately after
"Ignition 1" voltage is applied to the DERM and before
"Continuous Monitoring."
36VLR-The 36-volt loop reserve energy supplies from
the DERM which provide deployment power when
vehicle voltage is
low or lost in a frontal crash.
36 VLR DELAY
-Changing of the 36 VLR power supplies
is
inhibited briefly during "Turn-ON." This allows
detection of certain malfunctions related to "Ignition 1"
voltage which cannot be tested with 36 volts present.

--
9J-14 Supplemental Restraint System
INFLATOR MODULE HANDLING/SHIPPING/SCRAPPI G
LIVE (UNDEPLOYED) INFLATOR MODULE ~
Special care is necessary when handling and storing a
live (undeployed) inflator module. The rapid gas
generation produced during deployment of the air bag
could cause the inflator module, or an object in front of
the inflator module,
to be thrown through the air in the
unlikely event of an accidental deployment.
WARNING: WHEN CARRYING A LIVE INFLATOR
MODULE, MAKE SURE THE BAG OPENING IS
POINTED
AWAY FROM YOU. IN CASE OF AN
ACCIDENTAL DEPLOYMENT, THE BAG WILL THEN
DEPLOY WITH MINIMAL CHANCE OF INJURY.
NEVER CARRY THE INFLATOR MODULE BY THE
WIRES OR CONNECTOR ON THE UNDERSIDE OF
THE MODULE.WHEN PLACING A LIVE INFLATOR
MODULE ON A BENCH OR OTHER SURFACE,
ALWAYS FACE THE BAG AND TRIM COVER UP,
AWAY FROM THE SURFACE. THIS IS NECESSARY
SO
THAT A FREE SPACE IS PROVIDED TO ALLOW
THE AIR BAG TO EXPAND IN THE UNLIKELY EVENT
OF ACCIDENTAL DEPLOYMENT. NEVER REST A
STEERING COLUMN ASSEMBLY ON THE
STEERING WHEEL WITH THE INFLATOR MODULE
FACE
DOWN AND COLUMN VERTICAL.
OTHERWISE, PERSONAL INJURY MAY RESULT.
INFLATOR MODULE SHIPPING PROCEDURES
FOR
LIVE (UNDEPLOYED) INFLATOR
MODULES
Service personnel should refer to the latest Service
Bulletins for proper SRS inflator module shipping
procedures.
DEPLOYED INFLATOR MODULE
After the inflator module has been deployed, the surface
of the air bag may contain a powdery residue. This
powder consists primarily of cornstarch (used to
lubricate the bag as it inflates) and byproducts of the
chemical reaction. Sodium hydroxide dust( similar
to lye
soap)
is produced as a byproduct of the deployment
reaction. The sodium hydroxide then quickly reacts with
atmospheric moisture and is converted to sodium
carbonate and sodium bicarbonate (baking soda).
Therefore, it
is unlikely that sodium hydroxide will be
present after deployment. As with any procedures, you
should wear gloves and safety glasses.

Supplemental iraint System
TABLE OF CONTENTS
SUPPLEMENTAL RESTRAINT SYSTEM
{SRS)
SECTION 3 -SERVICE
9J-115
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.
SERVICE PRECAUTIONS . . . . . . . . . • . . . . . • • . . . . . . . . • . • • . . . . . . . . . . . • . . • • . . . . . . . 117
Disabling the SRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Enabling the SRS • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 117
Handling/Installation/Diagnosis • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 117
Inspections Required After Accident • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 117
DIAGNOSTIC ENERGY RESERVE MODULE (DERM) • • . • • . • • • • . . • . . . • • . . . . • . . . • 119
DISCRIMINATING SENSOR-FORWARD SENSOR LH . • . . • • . • . . • . . • . • . . . • • . . • • . 120
DISCRIMINATING SENSOR
-FORWARD SENSOR RH • . • . . . • • • . • . . . . • • . • . . . . . • • 121
DUAL POLE ARMING SENSOR . . . . . . . . . . • . . . . . • . . . . . . . . . . . . • • . . . . . . . . • . . . . . . . 122
DRIVER INFLATOR MODULE ............•..•........•....•....•....•.........
STEERING WHEEL •........•........•.•......••........•..••..•\
•....•....•..
SRS COIL ASSEMBLY ....•......•.•......•.............•••..•....•\
.....•..••
124
125
127
STEERING COLUMN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
PASSENGER INFLATOR MODULE . . . • . . . . . • . • • . . . . . . . . • . . . • • . . • • . . • • . . . . • • . . • 132
SPECIFICATION . .

. . . . . . . . . . . . . .
• . .
. . . . . .
• . .
. . . .
• • • • • • . . • • . • • • . .

.
• . .
. .
• • . .

.
• • 133

Supplemental Restraint System 9J-117
SERVICE PRECAUTIONS
CAUTION: WHEN PERFORMING SERVICE ON OR
AROUND SRS COMPONENTS OR SRS WIRING,
FOLLOW
THE PROCEDURES LISTED BELOW TO
TEMPORARILY
DISABLE THE SRS. FAILURE TO
FOLLOW PROCEDURES COULD RESULT IN
POSSIBLE AIR BAG DEPLOYMENT, PERSONAL
INJURY OR OTHERWISE UNNEEDED SRS
REPAIRS.
The DERM in Driver-Passenger SRS can maintain
sufficient voltage to cause a deployment for up to 2
minutes after the ignition switch is turned to
"OFF," the
battery is disconnected, or the fuse powering the DERM
is removed.
Many of the service procedures require removal of the
"AIR BAG" fuse, and disconnection of the inflator
modules from the deployment loop to avoid an accidental
deployment.
If the inflator module is disconnected from
the deployment loop as noted in the "Disabling the
SRS"
procedure that follows, service can begin immediately
without waiting for the 2 minute time period to expire.
DISABLING THE SRS
REMOVAL
• Turn the steering wheel so that the vehicle's wheels
are pointing straight ahead.
• Turn the ignition switch to "OFF"
1. Remove SRS fuse C-21, C-22, C-23 and C-24 from
left dash side lower fuse block.
2. Disconnect yellow
3-way connector at the base of
the steering column.
3. Remove
liP compartment door assembly, Refer to
"Passenger inflator module replacemenf' in section
9J-135.
4. Disconnect yellow 4-way connector behind the liP
compartment door assembly.
NOTE
• With the" AIR BAG" fuse removed and ignition switch
"ON," the "AiR BAG" warning lamp will be "ON." This
is normal operation and does not indicate
an SRS
malfunction.
ENABLING THE SRS
INSTALLATION
Turn ignition switch to "LOCK" and remove key.
1. Connect yellow 4-way connector of passenger
inflator module.
2. Install liP compartment door assembly, Refer to
"Passenger inflator module replacement" in section
9J-3.
3. Connect yellow 3-way connector at the base of the
steering column.
4. Install" AIR BAG" fuse C-21, C-22, C-23 and C-24 to
left dash side lower fuse block.
Tum ignition switch to
"RUN" and verify that the "AIR
BAG"
warning lamp flashes seven times and then turns
"OFF" If it does not operate as described, perform the
"SRS Diagnostic System Check" in section 9J-32.
HANDLING/INSTALLATION/DIAGNOSIS
1. Inflator modules should not be subjected to
temperatures above 65°C(150°F).
2. Discriminating s~nsors, inflator modules, arming
sensors, or DERMs should not be used if they have
been dropped from a height of 1
00 centimeters (3.28
feet) or more.
3. When a discriminating sensor or arming sensor is
replaced, it MUST be oriented with the arrow
on the
sensor pointing toward the front of the vehicle.
It is
very important for the discriminating sensors and
arming sensor to be located flat on the mounting
surface, parallel to the vehicle datum line.
It is
important that the sensor mounting surface is free of
any dirt or other foreign material.
4. Do not apply power to the SRS unless all
components are connected or a diagnostic chart
requests it, as this
will set a diagnostic trouble code.
5. The
"SRS Diagnostic System Check'' must be the
starting point of any SRS diagnostics. The
"SRS
Diagnostic System Check" will verify proper "AIR
BAG" warning lamp operation and will lead you to the
correct chart to diagnose any SRS malfunctions.
Bypassing these procedures may result in extended
diagnostic time, incorrect diagnosis, and incorrect
parts replacements.
INSPECTIONS REQUIRED AFTER ACCI­
DENT
CAUTION: CERTAIN SRS COMPONENTS MUST BE
REPLACED AFTER A FRONTAL
CRASH INVOLVING
AIR
BAG DEPLOYMENT.
In all types of accident regardless of "Air Bag"
deployment, visually inspect all the following
components and their points and replace as required:
- Passenger
Inflator Module
- Steering wheel
- SRS coil assembly
- Steering column
- Knee bolster and
Instrument panel mounting

9J-118 Supplemental Restraint System
attachments
- Driver seat and belt
- Passenger seat and belt
- Dual Pole Arming
Sensor
-Discriminating Sensors
-DERM
The sensor replacement policy specifies mandatory
replacement of the sensors, after crash involving
AIR
BAG deployment. If AIR BAG has not been deployd,
Replace the sensors
in the area of accident damage only.
The
"area of accident damage" is defined as that area of
the vehicle which is crushed, bent ,or damaged in other
ways. An example might be a front-end collision
in which
the forward portions of the vehicle have contacted
another vehicle, tree, guardrail,etc.
In this example,
1)
If AIR BAG has deployed, All Sensor should be
replaced.
2)
If AIR BAG has not deployed, replace the sensors
in the area of accident damage only.
sensor(s) on the radiator tie bar would require
replacement, since that portion of the vehicle was
damaged in the accident. The Dual Pole Arming Sensor
would not require mandatory replacement. Of course, if
the DERM sets a code and the diagnostic chart leads to
a faulty sensor that was not in the area of accident
damage, that sensor should also be replaced.Sensors
in
the area of accident damage should be replaced even if
those sensors do not appear to be damaged. Do not
attempt to determine whether a sensor is
OK-ALWAYS
replace it if it is in the area of accident damage.Aiso, if a
sensor is
in an area of accident damage,but the SRS has
NOT been deployed,replace the sensor.The sensor
bracket may be slightly bent,wiring may be
damaged, etc., and the sensor might not work properly
in
another collision. Again, do not attempt to determine
whether a sensor is
OK --ALWAYS replace it if it is in
the area of accident damage. Also,
inspect
SRS coil assembly wiring and steering
wheel for any signs of scorching, melting, or damage due
to excessive heat.
If the coil assembly wire or steering ~
wheel is damaged, replace them. The steering column
and wheel must be dimensionally checked to determine
if they are damaged. Refer to
in this Section 3 of this
manual.
Never use
SRS parts from another vehicle. This does not
include remanufactured parts purchased from an
authorized
ISUZU Dealer; they may be used for SRS
repairs.
Do not attempt to repair the forward discriminating
sensors ,the dual pole arming senor, the DERM, the
SRS
coil assembly, the inflator modules, the steering wheel, or
the steering column. Service of these items is
replacement only.
Verify replacement part numbers.
CAUTION: PROPER OPERATION OF THE
SENSORS AND SUPPLEMENTAL RESTRAINT
SYSTEM(SRS)REQUIRES THAT ANY REPAIRS TO
THE VEHICLE STRUCTURE RETURN IT TO ITS
ORIGINAL PRODUCTION CONFIGURATION.
II