air condition ISUZU TROOPER 1995 Workshop Manual

9J·82 Supplemental Restraint System
DTC37
HYBRID INFLATOR LOW PRESSURE
CIRCUIT DESCRIPTION
During normal "Ignition 1" voltage is applied from the
"C-23" fuse trough passenger low peraaaure warning
sensor to DERM st
"LPS" terminal "83". When the
pressure in the gas cylinder within the passenger inflator
module is operating normally the measured voltage will
be the same voltage as "Ignition 1" voltage. If the
passenger
low pressure warning sensor circuit opens or
short to ground the voltage measured st
"LPS" will
decrease to near ground voltage. When the voltage
measured
at"LPS" is outside the specified renge DTC 37
is set.
DTC WILL SET WHEN
The voltage measured at "LPS" terminal "83" is outside
the specified renge. This test is run every 100
milliseconds during "Continuous Montoring" tests.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp and sets
diagnostic trouble code.
DTC WILL CLEAR WHEN
The voltage measured at "LPS" terminal "83" is within a
specified rande which doesn't the diagnostic trouble
code, svery
100 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 due
to high resistance
in the "Passenger Low Pressure
Warning
Sensor."
3. This test checks for an open onside the "LPS" circuit.
4. This test checks for a short from the "LPS" cirsuit to
ground.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor
connection Passenger
Inflator Module terminal "1" or "4"
poor connection at DERM terminal "83", an open in CKT
1834 or CKT 1834 or an open inside the Passenger
Inflator Module.
SRS-1 JOINT CONNECTION 10 , ... IGNITION!
IGNITION 1 ORIVER SOURCE SENSE DRIVER 38VLR PASS.3eVLR PASS. SOURCE SENSE
REDUNDAT INDICATOR GROUND
PASS SIDE HIGH
PASS SIDE LOW
SPARE/I.PS DRIVER SEAT BELT
SERIAL DATA
DRIVER SIDE HIGH DRIVER SIDE LOW REDUNDANT INDICATOR IGNITION!
SRS INDICATOR
..

9J-84 Supplemental Restraint System
DTC42
LOOP ENERGY RESERVE VOLTAGE LOW
CIRCUIT DESCRIPTION
During the "Turn-ON" tests, performed at the beginning
of each ignition
cycle, the DERM delays charging of the
"Driver "36
VLR" terminal "A4" and "Passenger 36 VLR"
terminal
"A3" power supplies. After delay has expired
both "36
VLR" power supplies are allowed to change.
The DERM monitors each
"36 VLR" power supply to
ensure each has changed to a
voltage above a specified
value within 1 0 seconds after "Ignition 1" voltage is first
applied to DERM. When either "36 VLR" power supply
does not reach the specified voltage within the allowed
time or, once reaching the voltage, falls it for 500
milliseconds, DTC 42 is set.
DTC WILL SET WHEN
The voltage at either "36 VLR" power supply does not
exceed a specified
value within 10 seconds after "Ignition
1" voltage is first applied to the DERM or once having
reached the specified
value, either "36 VLR" power
supply voltage falls below the specified value for 500
milliseconds.
This test is run each ignition cycle at
"Turn-ON" to detect a change time failure and, after
charging, tested 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 voltages measured at "Driver 36 VLR" terminal "A4"
and "Passenger 36
VLR" terminal "A3" are above a
specified
value for 500 milliseconds.
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
2. This test checks whether the DERM has set the
diagnostic
trouble code falsely.
3. This test checks whether a malfunctioning dual pole
arming sensor is preventing dual pole arming sensor
is preventing the "Driver 36
VLR" or "Passenger 36
VLR" from charging.
4. This test checks for a short from the "Driver 36 VLR"
or "Passenger 36 VLR" circuit to 8+.
5. This test checks for a short from the "Driver 36 VLR"
or "Passenger 36 VLR" circuit to ground.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a short
from "Driver 36
VLR" or "Passenger 36 VLR" to B+ or
ground, or a short inside the
dual pole arming sensor.
SRS~1 JOINT CONNECTION IBOii 12 1G IGNITION 1
DRIVER 36VLR PASS.31VLR PASS. SOURCE SENSE
REDUNDAT INDICATOR GROUND
PASS SIDE HIGH PASS SIDE LOW
SPAREilPS
SERIAL DATA
DRIVER SIDE HIGH DRIVER SIDE LOW REDUNDANT INDICATOR IGNmON 1
1111

9J-86 Supplemental Restraint System
DTC43
DRIVER SOURCE FEED LOW
CIRCUIT DESCRIPTION
During normal, non-deployment operation of the SRS
the DERM monitors the voltage supplied through the
dual pole arming sensor to the high side of the driver
deployment loop at the "Driver Source Sense" terminal
"AS".
This measured voltage will have a value
approximately equal to "Driver 36 VLR." When the
voltage measured at "Driver Side Low" terminal "88" is
in its normal operating range, indicating driver
deployment loop integrity has been maintained, while
simultaneously
the voltage measured at "Driver Source
Sense"
is a specified amount below "Driver 36 VLR" for
SOO milliseconds DTC 43 is set.
DTC WILL SET WHEN
The voltage measured at "Driver Side Low" terminal "88"
is within a specified percentage of "Driver 36 VLR" while
simultaneously
the voltage measured at "Driver Source
Sense" terminal
during the "Continuous Monitoring"
tests.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp and sets
a diagnostic
trouble code.
DTC WILL CLEAR WHE
The voltage measured at "Driver Side Low" terminal "88"
is within a specified percentage of "Driver 36 VLR" while
simultaneously
the voltage measured at "Driver Source
Sense" terminal "AS"
is within a specified amount of
"Driver 36 VLR" for SOO milliseconds.
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
2. This test checks for an open in "Driver Source
Sense"
circuit.
3. This test checks for a short from the "Driver Source
Sense"
circuit to ground.
4. This test determines whether the malfunction is due
to increased resistance across the "Driver
Source
Sense"
resistor in the dual pole arming sensor.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor
connection to the DERM at terminal "AS", a poor
connection to the dual pole arming sensor at terminal "6",
an open or short to ground in CKT 1811 or a partial open
inside the
dual pole arming sensor.
SRS-1 FUSE JOINT CONNECTION ___ sR~S~C-~23-10_A __ ~'NK----~·~·~~----------~~-Pw--~•·~~---TO IGNITION SWITCH
FUSE! SRS C-24 10A , ... REO
TO FUSE 1001 ~~~~g~ _S_R_.S C,.:;.:·2:i-2 -10A--~r'f"---....l!!!<'----• 1111
181Z 1113
1814
B RED
IGNITION 1 IGNITION 1
DRIVER 36VLR PASS.38VLR PASS. SOURCE SENSE
REDUNOAT INDICATOR GROUND
PASS SlOE HIGH
PASS SIDE LOW
SERIAL DATA
SRS INDICATOR
..

9J-88 Supplemental Restraint System
DTC44
PASSENGER SOURCE FEED LOW
CIRCUIT DESCRIPTION
During normal, non-deployment operation of the SRS
the DERM monitors the voltage supplied through the
dual pole arming sensor to the high side ofthe passenger
deployment
loop at the "Passenger Source Sense"
terminal
"AS". This measured voltage will have a value
approximately equal to "Passenger 3S VLR." When the
voltage measured at "Passenger Side Low" terminal "87"
is in its normal operating range, indicating passenger
deployment
loop integrity has been maintained, while
simultaneously
the voltage measured at "Passenger
Source Sense" is a specified amount below "Passenger
3S VLR" for 500 milliseconds DTC 44 is set.
DTC WILL SET WHEN
The voltage measured at "Passenger Side Low" terminal
"87"
is within a specified percentage of "Passenger 3S
VLR" while simultaneously the voltage measured at
"Passenger Source Sense" terminal "AS" is within a
specified amount
below "Passenger 3S VLR" for 500
milliseconds.
This test is run every 1 00 milliseconds
during the "Continuous Monitoring" tests.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp and sets
a diagnostic
trouble code.
TO IGNITION SWITCH
FUSEj SRS C·24
10A , ... D
FUSE SRS C·23 10A 1001
DTC WILL CLEAR WHEN
The voltage measured at "Passenger Side Low" terminal
"87"
is within a specified percentage of "Passenger 3S
VLR" while simultaneously the voltage measured at
"Passenger Source Sense" terminal "AS" is within a
specified amount of "Passenger 3S VLR" for 500
milliseconds.
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
2. This test checks for an open in "Passenger Source
Sense" circuit.
3. This test checks for a short from the "Passenger
Source Sense" circuit to ground.
4. This test determines whether the malfunction is due
to increased resistance across the
"Passenger
Source Sense" resistor in the dual pole arming
sensor.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor
connection to the DERM at terminal "AS", a poor
connection to the dual pole arming sensor at terminal "1",
an open or short to ground in CKT 1814 or a partial open
inside the
dual pole arming sensor.
SRS-1 JOINT CONNECTION ~ IGNITION1
DRIVER 36VLR PASS. l&VLR PASS. SOURCE SENSE
PASS SIDE HIGH PASS SIDE LOW
1---""--:t--':1--7-7---7---""103"-4 --BLKIBLU 1--""--7-------:7-7--7--'TO ~fc~E-LT_,.,_BLU
~~~~~7----~11~~---W~fflE .J~L -----llli-BRN CONNECTOR 1811 11!120
..

9J-90 Supplemental Restraint System
DTC51
FRONTAL
CRASH DETECTED
CIRCUIT DESCRIPTION
Closure of the dual pole arming sensor is detected when
the voltage measured at "Driver
Side High" terminal "89"
or at "Passenger Side High" terminal "A7" is within a
specified
amount of its respective deployment loop
supply voltage.
Closure of either discriminating sensor is
detected when the voltage measured at "Driver
Side
High" terminal "88" or at "Passenger Side High" terminal
"87" is within a specified amount of ground potential.
When both conditions are met simultaneously
on either
driver side
or passenger side for not less than 250
milliseconds "Crash Data" is recorded and DTC 51 is set.
DTC WILL SET WHEN
Closure of the dual pole arming sensor and at least one
discriminating sensors is detected for not less than
250
microseconds on either the driver side or passenger
side. Conditions are monitored whenever the DERM is
functioning
normally.
ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp, records
"Crash
Data," and sets a diagnostic trouble code.
TO IGNITION SWITCH
FUSE! SRS C-24 10A 1101 R D
DTC WILL CLEAR WHEN
A scan tool "Clear Codes" command is received by the
DERM.
DTC CHART TEST DESCRIPTION
Number(s) below refer to step number(s) on the
diagnostic chart.
3. If inflator module(s) has not deployed, DTC 51 may
have set falsely.
4. If DTC 51 has set with no signs of frontal impact, the
diagnostic trouble code has set falsely.
5. This test checks for a DERM malfunction setting the
diagnostic trouble code.
6. This test checks for a DERM malfunction setting the
diagnostic trouble code.
7. This test determines whether the diagnostic trouble
code was set inadvertently during diagnosis.
8. When a frontal crash has occurred, it is necessary to
perform the indicated procedures to ensure the
SIR
system is fully functional.
IGNITION 1
DRIVER 36VLR PASS.3SVLR PASS. SOURCE SENSE
PASS SIDE HIGH
PASS SIDE LCIW
SERIAL DATA
SAS INDICATOR

9J-94 Supplemental Restraint System
DTC53
DRIVER SIDE LOW HIGH RESISTANCE
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
allowing this resistance to be calculated.
The normal, non-deployment current flow through the
driver
deployment loop is also affected since the DERM
is
supplying ground through a resistor bypassing the
ground
supplied by the resistance of the discriminating
sensor network. When the
voltage difference between
"Driver Side High" terminal "B9" and "Driver Side Low"
terminal "B8" is above a specified value DTC 53 is set.
DTC WILL SET WHEN
The voltage difference between "Driver Side High"
terminal "B9" Driver Side Low" terminal "B8" is above 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-O.N,"
2) No "higher priority faults" are detected dunng
"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 due
to a high resistance or open
in the "Driver Side Low"
circuit between the DERM and the Steering
column
harness connector.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor
connection at DERM
terminal "B8" or an open in CKT
IB20.
The test for this diagnostic trouble code is run only
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.
iYOS BLK/RE
.rBODY t824 VLT IB21J
DRIVER 36VLR PASS. 38VLR PASS. SOURCE SENSE
PASS SIDE HIGH
PASS SIDE LOW
l---....!E:L_-+--4+j-+-___..!!IB3~4--BLK/BLU
~-'!W.-4---4-~----'TO ~iJELT '"*' BLU
SERIAL DATA
DRIVER SIDE HIGH DRIVER SIDE LOW REDUNDANT INDICATOR IGNITION 1
SRS INDICATOR

9J-96 Supplemental Restraint System
DTC54
PASSENGER SIDE LOW HIGH RESISTA E
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 allowing
the resistance to be calculated. The normal,
non-deployment current flow through the passenger
deployment loop is also affected since the DERM is
supplying ground through a resistor bypassing the
ground
supplied by the resistance of the discriminating
sensor network. When the
voltage difference between
"Passenger Side
High" terminal "A7" and "Passenger
Side Low''
terminal "B7" is above a specified value DTC
54 is set.
DTC WILL SET WHEN
The voltage difference between "Passenger Side High"
terminal "A7"
and "Passenger Side Low" terminal "B7" is
above 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)"1gnition 1" 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 due
to a high resistance or open in the "Passenger Side
Low" circuit between the DERM and the passenger
inflator module harness connector.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor
connection at DERM
terminal "B7" or an open in CKT.
The test for this diagnostic trouble code is run only 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 1105 1 10 TO FUSE IGNITION SWITCH SRS C-22 10A
PASS SIDE HIGH
PASS SIDE LOW
SERIAL
DATA
SRS INDICA TOR
•

9J-98 Supplemental Restraint System
DTC55
DERM INCOMPATIBILITY
CIRCUIT DESCRIPTION
During the "Initiator Assembly Resistance Test" the
DERM grounds the "Passenger
Side Low" terminal "B7"
and measures the voltage at "Driver Source Sense"
terminal "AS" , "Passenger Source Sense" terminal "A6"
and "Driver Side Low" terminai"B8". The DERM monitors
"Driver
Source Sense" to ensure that "Driver 36 VLR" is
fully charged and supplying voltage to the high side of the
driver deployment loop. When this condition is met, the
measurement at "Passenger
Source Sense" indicates
no voltage is being
supplied to the high side of the
passenger deployment loop and grounding "Passenger
Side Low'' does no ground "Driver Side Low," DTC 55 is
set.
DTC WILL SET WHEN
The conditions described above indicate a driver only
DERM has been installed in the vehicle. This test is run
once each ignition cycle during the
"Initiator Assembly
Resistance
Test" when: 1)No "higher priority faults" are
detected during
"Tum-oN," 2)No "higher priority faults"
are detected during "Continuous Monitoring
" for one
second, 3}No
"Crank" signal present, 4)"1gnition 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 due
to a high resistance
or open in the "DIAGNOSTIC
CODES REQUEST"
circuit between the DERM and
the ground.
3. This test determines whether the malfunction

is due
to a high resistance or open in the
"DIAGNOSTIC
CODES REQUEST"
circuit between the DERM and
the ground.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor
connection at DERM terminal
"AS" or an open in CKT
IY06.
The test for this diagnostic trouble code is run only
while the "AIR BAG" warning lamp is performing
command is issued and the malfunction is still present,
the
DTC will not reappear until the next ignition cycle. ~
PASS.:MVUI PASS. SOURCe SENSE
PASS SlOE HIGH PASS SlOE LOW
SERIAL DATA
•

9J-102 Supplemental Restraint System
DTC62
REDUNDANT SRS INDICATOR CIRCUIT FAIL RE
CIRCUIT DESCRIPTION
When the ignition switch is first turned "ON" battery
voltage is applied to the
"AIR BAG" warning lamp and to
the
"Ignition 1" input terminals "A9" and "A10". The
DERM responds by flashing the
"AIR BAG" warning lamp
seven
times alternating between the primary and
redundant lamp drivers. The DERM monitors the
redundant lamp driver output by comparing the output
state at "SRS Indicator" terminal "B1" to the
microprocessor commanded state. When
"lgnition1" is
above a specified value and the output state does not
match the commanded state of the redundant lamp
driver for
400 milliseconds DTC 62 is set.
DTC WILL SET WHEN
"Ignition 1" voltage is above a specified value and the
output state at the
"SRS Indicator'' terminal "B 1" does not
match the commanded state of the redundant lamp
driver for
400 milliseconds. This test is run every 100
milliseconds during "Continuous Monitoring" tests.
FUSE
ACTION TAKEN
DERM attempts to turn "ON" the "AIR BAG" warning
lamp using the primary lamp driver 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 checks for an open in the "Redundant
Indicator Ground"
circuit.
3. This test determines whether the malfunction is due
to
an open in the "Redundant Indicator Ignition 1"
circuit.
DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor
connection to the DERM at terminal
"A2" or "B2", an open
in
CKT IY05 or an open in CKT IB03.
SRS-1 JOINT CONNECTION ___ sR~SrC~·23~1_M ___ ,PNK:----~"~~------------~"~~~~18~~~--TO IGNITION SWITCH IGNITION 1
FUSE!
SRS C-24 lOA 1800 RED
WKT/RED IGJ~oN --- REDUNDAT INDICATOR GROUND
PASS SIDE HIGH
PASS SIDE LOW
DRIVER SEAT BELT
CRANK
SERIAL DATA
DRIVER SIDE HIGH DRIVER SIDE LOW REDUNDANT INDICATOR
IGNITION 1
SRS INDICATOR

9J-1 04 Supplemental Restraint System
DESCRIPTION
DTC 71 AND/OR 75
INTERNAL DERM FAULT CIRCUIT
ACTION TAKEN
DTC 71 and/or DTC 75 is an indication of an internal
DERM malfunction and
will set if any of the following
conditions are detected:1 )DERM energy reserve voltage
discharge time failure for three consecutive ignition
cycles("Turn-ON" test), 2)DERM is unable to read from
or write to EEPROM(tested during
"EEPROM read/write
cycle"), 3)Either
"36 VLR" power supply voltage is above
a specified value for
500 milliseconds ("Continuous
Monitoring" test), 4)The DERM calculated number for
the vehicle
in which it is installed does not match the
value stored in EEPROM. DERM
turns
"ON" the "AIR BAG" warning lamp and sets
a diagnostic trouble code.
DTC WILL SET WHEN
Any of the indicated malfunctions are detected by the
DERM. Each of the failure conditions is tested at a
different time: 1 )At "Turn-ON," 2)Asynchronously,
3)During "Continuous Monitoring," 4)At
"Turn-ON."
DTC WILL CLEAR WHEN
The indicated malfunctions are not detected by the
DERM.
FUSE JOINT C~~N~CTION TO IGNITION
ru • .'jWITCH
SRS C-24 1~ , ... R D
--~SR~S~C~-~.1~~~-IPNK----~~·~~------------~~~w--~1-~---
>N-~~4---.::r---::r----___!!'B!!!!oa'-------WHT/REO
AL~L____mz._BRN CONNECTOR IB1t
1120
IGNITION 1 IGNITION 1 DRIVER SOURCE SENSE DRIVER 36VLR PASS.35VLR PASS. SOURCE SENSE
REDUNDAT INDICATOR GROUND
PASS SIDE HIGH
PASS SIDE LOW
SERIAL DATA
DRIVER SIDE HIGH DRIVER SIDE LOW REDUNDANT INDICATOR IGNITION1
SRS INDICATOR
•