relay ISUZU TROOPER 1995 Owners Manual

6E2-118 DRIVEABILITV AND EMISSIONS
FUEL METERING SYSTEM COMPONENTS
The fuel metering system (Fig. 6E2-68) consists of the
following components:
• Fuel supply components (fuel tank, pump and
lines).
• Fuel
pump electrical circuit.
• Fuel rail assembly, including:
-Fuel pressure control valve
• Throttle
body assembly, including:
-Idle Air Control valve
-Throttle Position Sensor
engine
sensors
• Fuel • :pump : ........
Fuel tank
Fig. 6E2-68
FUEL SUPPL V SYSTEM
The fuel supply is stored in the fuel tank. An electric
fuel
pump, located in the fuel tank with the gage
sending unit, pumps
fuel through an in-line fuel filter to
the
fuel rail assembly. The pump is designed to
provide
fuel at a pressure above the pressure needed
by the injectors. A fuel pressure control valve, an
integral part of the fuel rail assembly, keeps fuel
available
to the injectors at a controlled pressure.
Unused
fuel is returned to the fuel tank by a separate
line. See ENGINE FUEL (SECTION 6C) for replacement
procedures covering the fuel tank, fuel pump, in-line
filter
and fuel lines.
FUEL PUMP ELECTRICAL CIRCUIT
When the key is first turned "ON" without the engine
running, Engine
Control Module (ECM) will turn the fuel
pump relay "ON" for two seconds. This builds up the
fuel pressure quickly. lfthe engine is not started within
two seconds, the ECM will shut the fuel pump "OFF"
and wait until the engine starts. As soon as the engine
is cranked, the
ECM will turn the relay "ON" and run the
fuel pump.
An inoperative
fuel pump would cause a no start
condition. A
fuel pump which does not provide
enough pressure can
result in poor performance,
(refer to CHARTs A-5 and A-7).
FUEL RAIL ASSEMBL V
The fuel rail assembly (Fig. 6E2-69) is mounted to the
Inlet manifold, and performs several functions: It
positions the injectors in the cylinder head, it
distributes fuel evenly to the injectors, and it integrates
the
fuel pressure control valve into the fuel metering
system.
Fuel flow within the rail is shown in Fig. 6E2-
70.
Fig. 6E2-69
Fig. 6E2-70

Throttle Position (TP) Sensor
The Throttle Position (TP) Sensor is mounted on the
side
of the throttle body opposite the throttle lever
assembly.
Its function is to sense the current throttle
body position and relay that information to the ECM.
Knowledge ofTP is needed by the ECM to generate the
proper injector pulse width.
If the TP sensor senses a
Wide
Open Throttle, a voltage signal indicating this
condition is transmitted to the
ECM. The ECM will
widen the injector pulse, or increase the repetition rate,
permitting increased fuel
flow to each for the six fuel
injectors located in the fuel fail. As the throttle shaft
rotates in response to
movement of the accelerator
pedal (opening
or closing of the throttle body), the
throttle shaft transmits throttle
movement to the TP
sensor. A potentiometer (variable resistor) within the
TP sensor assembly creates a voltage that varies in
response to
TP. By applying a reference voltage (+5
VDC) to the TP sensor input, a varying voltage
(reflecting
TP) is available at the TP sensor output. The
voltage
output from the TP sensor is sent to the ECM
for use in determining current TP.
For further information ofTP sensor, refer to "ECM and
Sensors", Section
"6E2-C1 ". The TP sensor is an auto
zeroing type and cannot
be adjusted.
DRIVEABILITY AND EMISSIONS 6E2-121
INDUCTION AIR CONTROL PLATE
SYSTEM (DOHC) (Fig. 6E2-74)
This system consists of the Induction Air control plate
valve mounted in the common chamber
duct and a
vacuum operated diaphragm
which moves the Induction Air
Control Plate linkage. The vacuum to the diaphragm is
turned
"ON" or "OFF" by a vacuum switching solenoid
which is electrically operated by the
ECM.
Refer to CHART C-20 for diagnosing the Induction air
control plate system.
Manifold vaccum
1
Vacuum actuator
Induction air control plate valve
(noma! open)
Fig. 6E2-74
Engine control module (ECM)
Ignition switch
Canister, EGR, A.I.R. solenoids
DIAGNOSIS
FUEL METERING SYSTEM
Some failures of this system will result in the symptom,
"Engine Cranks But Will Not Run". If this condition
exists, see CHART A-3. This chart will determine
if the
problem is caused by the ignition system,
ECM or fuel
pump circuit.
If it's determined to be a fuel problem.
CHART A-5
or A-7 will be used. This includes the
injectors, fuel pressure control valve, fuel
pump and
fuel pump relay. The fuel system
wiring schematic
diagram is covered on the facing page
of CHART A-5.
If a malfunction occurs in the fuel control system, it
usually results in either a rich or lean Heated Oxygen
Sensor (H02S) signal condition. This condition is
sensed by the
H02S and the ECM will change the fuel
calculation (injector pulse width) based on
H02S input.
The change made to the fuel calculation will be
indicated
by a change in the block learn values which
can be displayed on a
"Scan tool". The ideal block learn
values are around 128 counts.
If the H02S senses a
lean condition, the
ECM will add fuel, resulting in a
block learn value above 128 counts.
If the H02S senses
a rich condition, the
ECM will subtract fuel, resulting in
a block learn value below 128 counts.
Block learn values can vary greatly, depending on
temperature, altitude and individual engine
tolerances. The programmed range for block learn
values is
58 to 198. Values within this range indicate
the system is in
"control". If a system is operating near
the extremes
of the block learn range during normal vehicle
operation, and there is a driveability complaint,
the fuel metering system should be checked. Refer to
the diagnostic trouble code
45 chart on the facing page
for potential causes of a rich condition (low block learn
values). Refer to the diagnostic trouble code 44 chart
facing page
for potential causes of a lean condition
(high block learn values).
If a driveability symptom
exists, also refer to the particular symptom in
"Symptoms", Section "6E2-B" for additional items to
check.
FUEL SYSTEM PRESSURE TEST
A fuel system pressure test procedure is included in
CHART A-7 under
"Fuel System Diagnosis" in "Engine
Components/Wiring Diagrams/Diagnostic
Charts",
Section "6E2-A" diagnostic charts.
IDLE AIR CONTROL (lAC) VALVE
A "Scan tool" will display Idle Air Control (lAC) valve
position in
"Counts" or steps. "0" steps indicates the
ECM is commanding the lAC valve to be driven all the
way in, to a fully seated position. This condition is
usually caused by a vacuum leak.
The higher the number
of counts, the more air is being
allowed to pass the
lAC valve. A functional check of the
lAC valve system (CHART C-2C) is provided in this
section. Refer to
"Refer, Unstable, or Incorrect Idle,
Stalling"
in "Symptoms", Section "6E2-B" for other
possibilities
for the cause of idle problems.

6E2-122 DRIVEABILITV AND EMISSIONS
INDUCTION AIR CONTROL PLATE
SYSTEM
Refer to CHART C-2D to diagnose the Induction air
control plate system.
ON-VEHICLE SERVICE
FUEL PUMP RELAY
The fuel pump relay is mounted in the engine
compartment.
Other than checking for loose
connectors, the only service possible is replacement.
MUL TIPORT FUEL INJECTION
COMPONENTS
WCAUTION:
VI • To reduce the risk of fire and personal injury, it
is necessary to relieve the fuel system pressure
before servicing
fuel system components.
• After relieving system pressure, a small
amount of fuel may be released when servicing
fuel lines or connections. In order to reduce the
chance
of personal injury, cover fuel line
fittings with a shop towel before disconnecting,
to catch any
fuel that may leak out. Place the
towel in an approved container when
disconnect is completed.
Fuel Pressure Relief Procedure
1. Remove fuel cap.
2. Remove fuel pump relay from underhood relay
box.
3. Start engine and allow to stall.
4. Crank engine for additional 30 seconds.
5. Remove negative battery cable.
FUEL RAIL ASSEMBL V
An eight digit identification number is stamped on the
side
ofthe fuel rail (Fig. 6E2-75). Refer to this number if
servicing or part replacement is required.
Names
of component parts appear in the numbered
list on the disassembled view (Fig. 6E2-75).
'fCAUTION:
• Do not attempt to remove the fuel inlet fitting
on the
fuel rail, it is staked in place. To do so will
result
in damage to the fuel rail or to the internal
0-ring seal.
•
Do care in removing the fuel rail assembly, to
prevent damage to the injector
electrical
connector terminals and the injector spray tips.
• Prevent dirt and other contaminants from
entering open lines and passages. Fittings
should be capped, and holes plugged, during
servicing.
Before
removal, the fuel rail assembly may be
cleaned with a spray type engine cleaner,
following
package instructions. Do not
immerse fuel rails in liquid cleaning solvent.
Fig. 6E2-75
I'
---------------------'
•

6E2-148 DRIVEABILITY AND EMISSIONS
CHART C-5
KNOCK SENSOR (KS) SYSTEM CHECK
(ENGINE KNOCK, POOR PERFORMANCE, OR POOR ECONOMY)
Circuit Description:
Knock Sensor (KS) is accomplished with a module that sends a voltage signal to the Engine Control Module {ECM).
As the knock sensor detects engine knock, the
voltage from the KS module to the ECM is shut "OFF" and this
signals the ECM to retard timing, if engine speed is over about 900.
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
CD If a diagnostic trouble code 43 is not set, but a KS signal is indicated while running at 1500 revolution per
minute,
listen for an internal engine noise. Under a no load condition, there should not be any detonation,
and
if knock is indicated, an internal engine problem may exist.
@ Usually a KS signal can be generated by tapping on the right exhaust manifold. This test can also be
performed at idle. Test number 1 was run at 1500 revolution per minute, to determine if a constant KS signal
was present, which would affect engine performance.
® This tests whether the KS signal is due to the sensor, a basic engine problem, or the KS module.
@ If the module ground circuit is faulty, the KS module will not function correctly. The test light should light
indicating the ground circuit is OK.
@ Contacting terminal "E" of KS module harness with a test light 12 volts, should generate a KS signal to
determine whether the knock sensor is faulty, or the KS module can't recognize a KS signal.
Diagnostic Aids:
If the KS system checks OK, but detonation is the complaint, refer to "Detonation/Spark Knock" symptom in
"Symptoms, "Section "6E2-8".
/ I
'
TWO-WAY CONNECTOR BLACK AT REAR OF INTAKE
I
-WHT
BLK!YEL
LOCATED REAR OF 0 INTAKE PLENUM
1------LT GRN/YEL
KNOCK
SENSOR
MODULE
BLK!YEL
GROUND
TOECM~ TERMINAL ENGINE A12 GROUND
0 LOCATEDAT _ DRIVER'S SIDE REAR OF CYLINDER HEAD
Fig. 6E2-91
RED/GRN
+ TO MAIN RELAY
ENGINE CONTROL
MODULE(ECM)
KNOCK SENSOR
SIGNAL INPUT
..

6E2-158 DRIVEABILITV AND EMISSIONS
CHART C-8
MANUAL TRANSMISSION (M/T) SHIFT LIGHT CHECK
Circuit Description:
The shift light indicates the best transmission shift point for maximum fuel economy. The light is controlled by the
Engine Control Module
(ECM) and is turned "ON" by grounding the ORN/BLU wire. The ECM uses information
from the following inputs to control the shift light.
The
ECM uses information from the following inputs to control the shift light:
• Engine coolant temperature sensor
• Throttle position sensor
• Vehicle speed sensor
• Revolution per minute
The
ECM uses the measured revolution per minute and the vehicle speed to calculate what gear the vehicle is in.
It's this calculation that determines when the shift light should be turned "ON".
Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.
fault in the
ECM.
® This checks the shift light circuit up to the ECM connector .If the shift light illuminates, then the ECM connector
is faulty
or the ECM does not have the ability to ground the circuit.
TO
IGNITION SWITCH
t
BLU/RED GRY/BLU
•
SHIFT SWITCHES #CLOSED" IN GEAR
BLU/ORN
SHIFT SHIFT LIGHT
LIGHT
RELAY
TO
LIGHTING SWITCH
Fig. 6E2-99
ENGINE CONTROL
MODULE(ECMl
SHIFT
LIGHT
CONTROL

DRIVEABILITV AND EMISSIONS 6E2-161
SECTION C-1 0
AIR CONDITIONING (A/C) COMPRESSOR CLUTCH CONTROL
SYSTEM
CONTENTS
General Description ..................... 6E2-161 On-Vehicle Service ...................... 6E2-161
Operation ........................... 6E2-161 Chart C-10 Air Conditioning (A/C) System
Diagnosis ............................. 6E2-161 Functional Check ...................... 6E2-162
GENERAL DESCRIPTION
OPERATION
This system consists of a high pressure cut-out switch,
Air Conditioning (A/C) compressor
relay, A/C thermo
switch relay, A/C controller and the compressor.
The high pressure cut-out switch
(normally closed),
opens when the head pressure gets too high. This will
disable
the A/C clutch, before damage can occur to the
compressor or other
A/C components.
When
A/C control switch is "ON" and the high pressure
switch and thermo switch are
closed, a request signal
is sent to the Engine Control Module (ECM). The ECM
will then energize the A/C clutch through the A/C
clutch relay. The A/C controller which is separate from
the ECM will then turn the A/C cooling fan "ON".
The A/C controller controls the A/C cooling fan, as well
as sending a signal to the ECM on model equipped with
automatic transmission.
The
ECM will disable the A/C clutch during Wide Open
Throttle,
or high power steering loads. The ECM has a
slight delay for clutch engagement to allow for the idle
to slightly increase. Refer to CHART C-1 0 for wiring and
circuit description.
DIAGNOSIS
Chart C-10 should be used for the electrical portion of
the A/C circuit. Section 1 B should be used for
diagnosing the refrigerant portion of the system. The
"Scan tool" will be used in diagnosing the system, as it
has the ability to read the A/C request inputto the ECM,
as well as displaying when the ECM has commanded
the
A/C clutch "ON".
ON-VEHICLE SERVICE
For removal and replacement of A/C components,
refer to
A/C (SECTION 1 B) in this Manual.

6E2-162 DRIVEABILITY AND EMISSIONS
CHART C-10
AIR CONDITIONING (A/C) SYSTEM FUNCTIONAL CHECK
Circuit Description:
When the Air Conditioning (A/C) diagnostic test mode is selected, the Engine Control Module (ECM) will supply a
ground to the
A/C clutch relay. Battery positive voltage is then supplied to the A/C clutch through the completing
of circuit through the thermo switch relay, which is part of the A/C "ON/OFF" switch circuit. If the A/C system
exhibits high pressure or
an overheating condition exist, the A/C system will be disabled by the open of the A/C
high pressure switch or the A/C thermo switch.
Diagnostic Aids:
The A/C high pressure switch is located in the high pressure side A/C hose.
The
thermo cut-out switch is part of the A/C evaporator mounted under the dash. For further information about
the
A/C system, refer to A/C (SECTION 1 8).
BRN
TONC FUSE
NC HIGH
PRESSURE SWITCH
(LOCATED IN
RECEIVER/DRYER)
LTGRN
BRN
NC Switch
NC DIODE
BRN a GRY!YEL
THERMO CUT­OUT RELAY
LTGRN PNK/ GRN
NCCOMP CLUTH RELAY
PARTOF1-­FAN I SWITCH I I CIRCUIT I __ I
BLK THERMO CUT-OUT MODULE j_
Fig. 6E2-100
ENGINE
CONTROL
MODULE (ECM)
NC COMPRESSOR CLUTCH RELAY DRIVER OUTPUT
NC REQUEST INPUT

DRIVEABILITV AND EMISSIONS 6E2-163
CHART C-10
AIR CONDITIONING (A/C) SYSTEM FUNCTIONAL CHECK
IGNITION "ON" ENGINE RUNNING.
CYCLE AIR CONDITIONING (A/C) SWITCH "ON" AND "OFF". A/C COMPRESSOR CLUTCH SHOULD
CYCLE "ON" AND "OFF"
DOES IT?
$
$
"SCAN TOOL" INSTALLED.
NO PROBLEM FOUND, REFER TO)>e€TIO'N REQUEST A/C "1B", AIR CONDITIONING"
"SCAN TOOL" SHOULD DISPLAY "YES" FOR FOR SERVICE OF A/C SYSTEM A/C REQUEST AND "ON" FOR A/C CLUTCH.
DOES IT?
$
$
IGNITION "ON", ENGINE "OFF". USING TEST BASIC A/C PROBLEM. REFER TO~ LIGHT, BACK PROBE ENGINE CONTROL MODULE "1B", AIR CONDITIONING"
TERMINAL C9 WITH A/C REQUESTED. LIGHT
SHOULD BE "ON". IS IT?
$ $
USING TEST LIGHT CONNECTED TO BATTERY IGNITION "OFF". REMOVE A/C THERMO
POSITIVE VOLTAGE, BACK PROBE ENGINE RELAY. IGNITION "ON" A/C REQUESTED, CONTROL MODULE TERMINAL PROBE THE GRN/WHT WIRE OF RELAY. "A2". LIGHT SHOULD BE "ON". LIGHT SHOULD BE "ON" IS IT?
IS IT?
I
$ $
~ $ OPEN IN PNK/GRN WIRE I OPEN IN GRN/WHTJ OPEN GRN WIRE
OPEN GRY/YEL WIRE OR WIRE. OR OR FAULTY A/C THERMO SWITCH FAULTY FAULTY A/C CLUTCH RELAY. OR COMPRESSOR RELAY. FAULTY THERMO SWITCH RELAY.
CLEAR DIAGNOSTIC TROUBLE CODES AND CONFIRM "CLOSED LOOP" OPERATION AND NO "CHECK ENGINE" MALFUNCTION INDICATOR LAMP.

AUTOMATIC TRANSMISSION (4L30-E) 7 A-69
CHART 1
DIAGNOSIS CONNECTOR AND VOLTAGE SUPPLY TEST
HOf AT All TIMES
r
L
GRN/WHT
FUSE C-14 15A
H-7 4
A4 C-90 DIAGNOSIS
CONNECTOR
(C-92) r------
1 I
----J 2
BLKI ORN
HOT IN ON OR START
FUSE C-8
15A I
I
__ _I
FUSE BOX
HOT AT ALL TIMES
---
l
A FUSE FL-3 30A
I I
I
I
H-13
BLKJYEL
1
[_ --
RED/WHT
L-___ _j
2
X-12
:1?.---- -:~t~v
I }-I t·---I L _______ _j
---r-12
H-42/o 8
3
BLK
RED/GRN
""--------i~ TO ENGINE
..- CONTROL
MODULE
(ECM)
YELl
BLK BLK!ORN
D16
BLKI
ORN
Cl Dl C-91 A7 AS C-90
RELAY& FUSE BOX
~------------------------BATTERY DIAGNOSTIC · · I
I INPUT INPUT GROUND IGNITION I
I INPUT I
TRANSMISSION
CONTROL MODULE
(TCM)
I SERIAL DATA
------------------------1 CB C-91
RED
YEL/BLU
L T GRN/BLU BLKIBLU
,_1_, ~n
I I ________ J
C12 C-2 r------------
1 I
I I
1...--------_J DATA LINK CONNECTOR (C-9)
ENGINE CONTROL MODULE (ECM)

7 A-90 AUTOMATIC TRANSMISSION (4L30-E)
DIAGNOSTIC TROUBLE CODE (DTC) 25
SUPPLY VOLTAGE TOO LOW
This DTC flashes the CHECK TRANS indicator and
sets the BACKUP
MODE.
Specification decreases with the transmission
oil temperature:
Circuit Description:
-40°C (-40°F) = S.7 volts
90°C (194°F) = 9.0 volts
150°C (304°F) = 9.2 volts The ignition voltage of Transmission Control
Module (TCM) terminals A7 and AS is monitored by
the TCM and when the voltage is too low (approx. 9
volts) the DTC25 is stored and the BACKUP MODE
is set.
@ The condition needs to be present for at least
1 second
• Action after the detection time: BACKUP MODE
Diagnostic Aids:
• This Diagnostic is an electrical test done by the
TCM.
• Recovery conditions: To recover, the ignition
voltage must be higher than specification.
Specification decreases
with the transmission oil
temperature:
-40°C (-40°F) = 9.2 volts
90°C (194°F) = 9.5 volts
150°C (304°F) = 9.6 volts
• Detection conditions:
CD Ignition voltage measured between TCM
terminal A7 or AS and ground C1 is lower
than specification .
. · fU I
I '
f:L;~soA L., ____ J
RELAY & FUSE BOX
1--, {)-:,.--____..J BATTERY
l
T
L __ I
r
I C-14 C-8 I I 15A 15A FUSE -__ + _ j BOX
H-13t 3
H-7 'x~.~~'---7 r ]_-
GRN/WHT
BATTERY I GROUND INPUT IGNITION I INPUT I
L-----------TRANSMISSION
CONTROL MODULE
(TCM) IGN.SW.
RED/WHT
C-1 C-1 C-2
A6 B1 C16
r -;ATTERV INPUT-l
I
I l _____ j
ENGINE
CONTROL MODULE
(ECM)
I I
I-_j GENERATOR