run flat ISUZU TROOPER 1995 User Guide

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

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.
•

Supplemental Restraint System 9J-13
ON-VEHICLE SERVICE
SERVICE PRECAUTIONS
WARNING: 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
"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 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
steering column.
3. Remove 1/P compartment door assembly, Refer to
"Passenger inflator module replacement" in section
9J-132.
4. Disconnect yellow 4-way connector behind the 1/P
compartment door assembly.
IMPORTANT
• With the "AIR BAG" fuse removed and ignition switch
"ON," if Fuse 21 left. 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 for passenger
inflator module.
2. 1/P compartment door assembly, Refer to
"Passenger inflator module replacemenf' in section
9J-3.
3. Connect yellow 2-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.
Turn ignition switch to
"RUN" and verify that the "AIR
BAG"
warning lamp flashes seven times and then turns
"OFP' If it does not operate as described, perform the
"SRS Diagnostic System Check" in section 9J-2.
HANDLING/INSTALLATION/DIAGNOSIS
1. Inflator modules should not be subjected to
temperatures above
65°C{150°F).
2. Discriminating sensors, inflator modules, arming
sensors, or DERMs should not be used if they have
been dropped from a height
of 91.4 centimeters
{3feet).
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.

9J-44 Supplemental Restraint System
DTC 15
PASSENGER INITIATOR CIRCUIT RESISTANCE HIGH
CIRCUIT DESCRIPTION
During the "Initiator Assembly Resistance Test" the
DERM grounds the
"Driver Side Low" terminal "BB" and
turns "ON" the passenger current source at the
"Passenger Side High" terminal "A7". This causes a
known amount of current to
flow through the passenger
initiator circuit. By monitoring the difference between the
voltage at the "Passenger Side High" terminal "A7" and
the "Passenger
Side Low" terminal "B7" the DERM
calculates the combined resistance of the passenger
inflator module, harness wiring CKTs IB21, IB22 and
IB24 and connector terminal contact.
DTC WILL SET WHEN
The combined resistance of the passenger inflator
module,
harness wiring CKT's IB21, IB22, and IB24 and
connector
terminal contact is above a specified value.
This test is run once each ignition cycle during the
"Initiator Assembly Resistance Tesf' when: 1) No "higher
priority faults" are detected during "Turn-ON," 2) No
"higher priority faults" are detected during "Continuous
Monitoring for one second, 3) No "Crank" signal present,
4) "Ignition 1" voltage is above a specified value.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp and sets
a diagnostic
trouble code.
DTC WILL CLEAR WHEN
The ignition switch is turned "OFF."
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
2. This test determines whether the malfunction is in
the passenger inflator module circuitry or in the
DERM wiring harness circuitry.
3. This test determines whether the malfunction is an
open in CKT's IB"21, IB22, IB24.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor
connection to the passenger
inflator module terminal "2"
or terminal "3" or a poor connection to the DERM at
terminal "A7''. The test for this diagnostic trouble code is
only run while the "AIR BAG" warning lamp is performing
the
bulb check. When a scan tool "Clear Codes"
command is issued and the malfunction is still present,
the
DTC will not reappear until the next ignition cycle.
DRIVER 36VLR PASS. 36VLR PASS. SOURCE SENSE
REDUNDAT INDICATOR GROUND
PASS SIDE HIGH
PASS SIDE LOW
SERIAL DATA
SRS INDICATOR
Ill

9J-46 Supplemental Restraint System
DTC 16
PASSENGER INITIATOR CIRCUIT RESISTANCE LOW
CIRCUIT DESCRIPTION
During the "Initiator Assembly Resistance Test" the
DERM grounds the "Driver
Side Low" terminal "B8" and
turns "ON" the passenger current source at the
"Passenger Side High" terminal "A7". This causes a
known amount of current to
flow through the passenger
initiator circuit. By monitoring the difference between the
voltage at the "Passenger Side High" terminal "A7" and
the "Passenger
Side Low" terminal "B7" the DERM
calculates the combined resistance of the passenger
inflator module, harness wiring CKTs IB21, IB22 and
IB24 and connector terminal contact.
DTC WILL SET WHEN
The combined resistance of the passenger inflator
module,
harness wiring CKT's IB21, IB22, and IB24 and
connector
terminal contact is below a specified value.
This test is run once each ignition cycle during the
"Initiator Assembly Resistance Test" when: 1) No "higher
priority
faults" are detected during "Turn-ON," 2) No
"higher priority
faults" are detected during "Continuous
Monitoring" for one second,
3) No "Crank" signal present,
4)
"Ignition 1" voltage is above a specified value.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp and sets
a diagnostic
trouble code.
1805
DTC WILL CLEAR WHEN
The ignition switch is turned "OFF."
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
2. DTC 16 and 22 will set simultaneously when the
"Driver Side High" circuit is shorted to the
"Passenger Side High" circuit due to parallel current
paths.
3. This test determines whether the malfunction is in
the passenger inflator module circuitry or in the
DERM wiring harness circuitry.
4. This test checks for a short from the "Passenger Side
High" circuit to the "Passenger Side Low" circuit.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a short
between CKT's
IB15, IB21, IB24 and CKT's IB10, IB16,
IB19
or CKT's IB17, IB18, IB20, IB22, IB25, IB36. The
test for this diagnostic
trouble code is only run while the
"AIR BAG" warning lamp is performing the bulb check.
When a scan
tool "Clear Codes" command is issued and
the
malfunction is still present, the DTC will not reappear
until the next ignition cycle.
SRS·1 JOINT CONNECTION 12 10 LBOe TO FUSE 1807 ~~~2~--SR~SC~-2+21-0A--~~--~---
IGNITION 1 IGNITION1 1111 1812 1813 DRIVER JeVLR
PASS. 36VLR
PASS. SOURCE
SENSE
REDUNDAT
INDICATOR
GROUND
PASS SIDE HIGH
PASS SIDE LOW
SERIAL DATA
SRS INDICATOR
•

9J-52 Supplemental Restraint System
DTC 19
PASSENGER INITIATOR CIRCUIT VOLTAGE HIGH
CIRCUIT DESCRIPTION
During normal, non-deployment operation of the SRS,
a small amount of current flows through both the driver
and passenger deployment loops. The diagnostic
resistors within the dual pole arming sensor and the
discriminating sensors
along with the resistance of the
inflator modules cause voltage drops within the
deployment loops. The DERM monitors the voltage at
"Passenger
Side Low" terminal "87" to detect shorts or
opens within the passenger deployment
loop. When the
measured
voltage is above a specified percentage of
"Passenger 36
VLR" for 500 milliseconds DTC 19 is set.
DTC WILL SET WHEN
The voltage measured at "Passenger Side Low'' terminal
"87''
is above a specified percentage of "Passenger 36
VLR" for 500 milliseconds and DTC 35 is not set. This
test is
run every 100 milliseconds during the "Continuous
Monitoring" tests.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp and sets
a diagnostic
trouble code.
DTC WILL CLEAR WHEN
The voltage measured at "Passenger Side Low" terminal
"87"
is within a specified percentage of "Passenger 36
VLR" for
500 milliseconds.
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
2. DTC 19 and 23 together means that there is both
open Forward
Sensor LH and Forward Sensor RH,
or internal short in dual pole arming sensor.
3. This test checks for decreased resistance in driver
side diagnostic resistors of the
dual pole arming
sensor.
4. This test checks for decreased resistance in the
passenger side diagnostic resistors of the
dual pole
arming sensor.
5. This test determines whether the malfunction is in
the Forward
Sensor RH/LH circuitry.
7. This test determines whether the malfunction is in
the FORWARD SENSOR RH/LH ENG, ROOM
HARNESS or FORWARD SENSOR RHILH.
1
o. This test determines whether the malfunction is in
the
FORWARD SENSOR RH/LH.
DIAGNOSTIC AIDS
An open between the passenger inflator module and the
forward discriminating sensor causes the
voltage to
increase at "Passenger Side Low'' due to the loss of a
ground path. This
also causes the voltage to decrease at
"Driver Side Low" due to decreased current flow through
the discriminating sensor network.
Intermittent condition
is
likely to be caused by backed out shorted terminals on
the arming sensor harness connector, poor connection
at any of the discriminating sensor terminals.
•

9J-54 Supplemental Restraint System
DTC21
DRIVER INITIATOR CIRCUIT RESISTANCE HIGH
CIRCUIT DESCRIPTION
During the "Initiator Assembly resistance Test" the
DERM grounds the
"Passenger Side Low" terminal "B7"
and turns "ON" the driver current source at

the
"Driver
Side
High" terminal "B9". This causes a known amount
of Current to flow through the driver initiator circuit. By
monitoring the difference between the voltage at the
"Driver Side High" terminal "B9" and the "Driver Side
Low'' terminal "B8" the DERM calculates the combined
resistance of the driver inflator module, SRS coil
assembly, harness wiring CKTs IB16, IB17 and IB19 and
connector terminal contact.
DTC WILL SET WHEN
The combined resistance of the driver inflator module,
SRScoilassembly, harness wiring
CKT's IB16, IB17 and
IB19 and connector terminal contact is above a specified
value. This test is run during the
"Initiator Assembly
Resistance
Test" when: 1) No "higher priority faults" are
detected during
"Turn-QN," 2) No "higher priority faults"
are detected during
"Continuous Monitoring" for one
second, 3) No
"Crank" signal present, 4) "Ignition 1"
voltage is above a specified value.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp and sets
diagnostic trouble code.
FUSE
TO IGNITION SRS C-2310A 11105 SWITCH
TO
IGNITlON SWITCH
~i SRS
C-24 lOA 1800 AD
DTC WILL CLEAR WHEN
The ignition switch is turned "OFF."
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
2. This test determines whether the malfunction is in
the driver inflator module circuitry or
in the DERM
wiring harness circuitry.
3. This test determines whether the malfunction is an
open in IB19.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor
connection at: the yellow
2-way connector near the base
of the steering column, DERM terminals
"B8" or "B9", or
the connection at the top of steering column to the driver
inflator module.
SRS·l JOINT CONNECTION
" FUSE SRS C-2210A
BL ED
1800
1807 1111 1812 1113 11114
IGNITION! IGNITION 1
DRIVER 36VLR PASS. 36VLR PASS. SOURCE
SENSE
REDUNDAT INDICATOR GROUND
SRS·1 PASS SIDE HIGH
PASS SIDE LOW
IB34
1831 FUSE STARTER C-10A
SERIAL DATA FUSE
11120
1803
SRS INDICA TOR
•

9J-56 Supplemental Restraint System
DTC22
DRIVER INITIATOR CIRCUIT RESISTANCE LOW
CIRCUIT DESCRIPTION
During the "Initiator Assembly resistance Test" the
DERM grounds the "Passenger
Side Low" terminal "B7"
and turns "ON" the driver current source at the "Driver
Side High" terminal "B9". This causes a known amount
of current to flow through the driver initiator circuit. By
monitoring the difference between the voltage at the
"Driver Side High" terminal "B9" and the "Driver Side
Low"
terminal "B8" the DERM calculates the combined
resistance of the driver inflator module, SRS coil
assembly, harness wiring CKTs IB16, IB17 and IB19 and
connector terminal contact.
DTC WILL SET WHEN
The combined resistance of the driver inflator module,
SRS coil assembly, harness wiring CKT's IB16, IB17 and
IB19 and connector terminal contact is above a specified
value. This test is run during the
"Initiator Assembly
Resistance
Test" when: 1) No "higher priority faults" are
detected during
"Turn-ON," 2) No "higher priority faults"
are detected during "Continuous Monitoring" for one
second,
3) No "Crank" signal present, 4) "Ignition 1"
voltage is above a specified value.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp and sets
diagnostic trouble code.
DTC WILL CLEAR WHEN
The ignition switch is turned "OFF."
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
2. DTC 16 and 22 will set simultaneously when the
"Driver Side High" circuit due to parallel current
paths.
3. This test determines whether the malfunction is in
the driver inflator module circuitry or in the DERM
wiring harness circuitry.
4. This test checks for a short from the "Driver Side
High"
circuit to the "Driver Side Low'' circuit.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a short
between CKT
IB17 and CKT IB16 or CKT IB19 or a
malfunctioning shorting
clip at the base of the steering
column. The test for this diagnostic trouble code is only
run while the "AIR BAG" warning lamp is performing the
bulb check. When a scan tool
"Clear Codes" command
is issued and the malfunction is
still present, the DTC will
not reappear until the next ignition cycle.
SAS·1 JOINT CONNECTlON FUSE SASC-2310A -. IGNITION 1 IGJ,\\oN FUSE SWrrtH SRS C-22 10A
DRIVER 38VLR PASS.30VLA PASS. SOURCE SENSE
REDUNOAT INOtcATOR GROUND
PASS SIDE HIGH PASS SIDE LOW
SPAREAPS
SERIAL DATA
DRIVER SIDE HIGH DRIVER SIDE LOW REDUNDANT INDICATOR
IGNITION 1
SRS INDICATOR
..

9J-58 Supplemental Restraint System
DTC23
DRIVER INITIATOR CIRCUIT VOLTAGE HIGH
CIRCUIT DESCRIPTION
During normal, non-deployment operation of the SRS,
a small amount of current flows through both the driver
and passenger deployment loops. The diagnostic
resistors within the dual pole arming sensor and the
discriminating sensors
along with the resistance of the
inflator modules cause voltage drops within the
deployment loops. The DERM monitors the voltage at
"Driver Side
Low" terminal "88" to detect shorts or opens
within the driver
deployment loop. When the measured
voltage is above a specified percentage of "Driver 36
VLR for
500 milliseconds DTC 23 is set.
DTC WILL SET WHEN
The voltage measured at "Driver Side Low" terminal "88"
is above a specified percentage of "Driver 36 VLR" for
500 milliseconds and DTC 35 is not set. This test is run
during the
"Continuous Monitoring" tests.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp and sets
a diagnostic trouble code.
DTC WILL CLEAR WHEN
The voltage measured at "Driver Side Low" terminal "88"
is within a specified percentage of "Driver 36 VLR" for
500 milliseconds.
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
2. DTC 19 and 23 together means that there is both
open FORWARD
SENSOR LH and FORWARD
SENSOR RH, or internal short in dual pole arming
sensor.
3. This test determines whether the
malfunction is an
open in SRS HARNESS.
DIAGNOSTIC AIDS
An open between the driver inflator module harness
connector and the discriminating sensor interconnect
causes the
voltage to increase at "Driver Side Low" due
to the
loss of a ground path. This also causes the voltage
to decrease at "Passenger Side Low'' due to decreased
current
flow through the discriminating sensor network.
OERM
IGNITION 1
IGNITION 1 DRIVER SOURCE SENSE DRIVER 38VLR PASS. 38VLR PASS. SOURCE SENSE
REDUNDAT INDICATOR GROUND
PASS SIDE HIGH
PASS SIDE LOW
SRS INDICATOR
•

9J-60 Supplemental Restraint System


DTC 24 {PAGE 1 OF 3)
INITIATOR CIRCUIT VOLTAGE LOW
' I,
CIRCUIT DESCRIPTION
During normal, non-deployment operation of the SRS,
a small amount of current flows through both the driver
and passenger deployment loops. The diagnostic
resistors within the dual pole arming sensor and the
discriminating sensors
along with the resistance of the
inflator modules cause voltage drops within the
deployment loops. The DERM monitors the voltage at
"Driver Side Low" terminal "88" and "Passenger Side
Low" terminal "87" to detect shorts or opens within the
driver deployment
loop. When the measured voltage at
terminal "88" or "87" is below a specified percentage of
its respective Driver 36 VLR power
supply voltage for
500 milliseconds DTC 24 is set.
DTC WILL SET WHEN
The voltage measured at "Driver Side Low" terminal "88"
is below a specified percentage of "Driver 36 VLR" or
when the
voltage measured at "Passenger Side Low"
terminal "87" is below a specified percentage of
"Passenger 36 VLR" for 500 milliseconds. This test is run
during the "Continuous Monitoring" test.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp and sets
a diagnostic
trouble code.
DTC WILL CLEAR WHEN
The voltage measured at "Driver Side Low" terminal "88"
is within a specified percentage of "Driver 36 VLR" and
the
voltage measured at "Passenger Side Low" terminal
"87"
is within a specified percentage of "Passenger 36
VLR" for 500 milliseconds.
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
2. This test determines whether the malfunction is
occurring
in the steering column circuitry.
3. This test determines whether the malfunction is
occurring
in the passenger inflator module circuitry.
4. This test check's for a short from the SRS COIL to
ground.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor
connection at DERM terminals
"A3" and "A4", dual pole
arming sensor terminals "2", "4", "5" or"7",water intrusion
in any discriminating sensor, an open in CKT 1810 or
CKT 1815, ora short to ground in CKT's 1810,1815, 1816,
1817, 1818,
1819, 1820, 1821, 1822, 1824, 1825, 1836.
Refer to DTC 25 diagnose a possible short to B+. When
the malfunction occurs during
an ignition cycle DTC 24
will set. If the malfunction is present at the beginning of
the next ignition
cycle DTC 25 will set and DTC 24 will be
moved to a history
file.
SAS·1 JOINT CONNEC'TlON ,, .
PASS SIDE HIGH PASS SIDE LOW
SRS INDICATOR