1998 ISUZU TROOPER Electrical wiring diagram

6E±225 4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
General Description
(ECM and Sensors)
57X Reference ECM Input
The engine control module (ECM) uses this signal from
the crankshaft position (CKP) sensor to calculate engine
RPM and crankshaft position at all engine speeds. The
ECM also uses the pulses on this circuit to initiate injector
pulses. If the ECM receives no pulses on this circuit, DTC
P0337 will set. The engine will not start and run without
using the 57X reference signal.
A/C Request Signal
This signal tells the ECM when the A/C mode is selected
at the A/C control head.
Refer to
A/C Clutch Circuit Diagnosis for A/C wiring
diagrams and diagnosis for the A/C electrical system.
Crankshaft Position (CKP) Sensor
The crankshaft position (CKP) sensor provides a signal
used by the engine control module (ECM) to calculate the
ignition sequence. The CKP sensor initiates the 57X
reference pulses which the ECM uses to calculate RPM
and crankshaft position.
Refer to
Electronic Ignition System for additional
information.
Camshaft Position (CMP) Sensor and
Signal
The camshaft position (CMP) sensor sends a CMP signal
to the ECM. The ECM uses this signal as a ªcylinder
distinctionº to trigger the injectors in the power order. If the
ECM detects an incorrect CMP signal while the engine is
running, DTC P0341 will set, and the ECM triggers the
injectors in the power order.
Refer to
DTC P0341.
Engine Coolant Temperature (ECT) Sensor
The engine coolant temperature (ECT) sensor is a
thermistor (a resistor which changes value based on
temperature) mounted in the engine coolant stream. Low
coolant temperature produces a high resistance of
100,000 ohms at ±40
C (±40
F). High temperature
causes a low resistance of 70 ohms at 130
C (266
F).
The ECM supplies a 5-volt signal to the ECT sensor
through resistors in the ECM and measures the voltage.
The signal voltage will be high when the engine is cold and
low when the engine is hot. By measuring the voltage, the
ECM calculates the engine coolant temperature. Engine
coolant temperature affects most of the systems that the
ECM controls.
The Tech 2 displays engine coolant temperature in
degrees. After engine start-up, the temperature should
rise steadily to about 85
C (185
F). It then stabilizes
when the thermostat opens. If the engine has not been
run for several hours (overnight), the engine coolanttemperature and intake air temperature displays should
be close to each other. A hard fault in the engine coolant
sensor circuit will set DTC P0117 or DTC P0118.
0016
Electrically Erasable Programmable Read
Only Memory (EEPROM)
The electrically erasable programmable read only
memory (EEPROM) is a permanent memory chip that is
physically soldered within the ECM. The EEPROM
contains the program and the calibration information that
the ECM needs to control powertrain operation.
Unlike the PROM used in past applications, the EEPROM
is not replaceable. If the ECM is replaced, the new ECM
will need to be programmed. Equipment containing the
correct program and calibration for the vehicle is required
to program the ECM.
Intake Air Temperature (IAT) Sensor
The intake air temperature (IAT) sensor is a thermistor
which changes its resistance based on the temperature of
air entering the engine. Low temperature produces a high
resistance of 100,000 ohms at ±40
C (±40
F). High
temperature causes low resistance of 70 ohms at 130
C
(266
F) . The ECM supplies a 5-volt signal to the sensor
through a resistor in the ECM and monitors the signal
voltage. The voltage will be high when the incoming air is
cold. The voltage will be low when the incoming air is hot.
By measuring the voltage, the ECM calculates the
incoming air temperature.
The Tech 2 displays the temperature of the air entering
the engine. The temperature should read close to the
ambient air temperature when the engine is cold and rise
as underhood temperature increases. If the engine has
not been run for several hours (overnight), the IAT sensor
temperature and engine coolant temperature should read
close to each other. A fault in the IAT sensor circuit will set
DTC P0112 or DTC P0113.

6E±228
4JX1±TC ENGINE DRIVEABILITY AND EMISSIONS
General Description (Air Induction)
Air Induction System
The air induction system filters contaminants from the
outside air, and directs the progress of the air as it is
drawn into the engine. A remote-mounted air cleaner
prevents dirt and debris in the air from entering the
engine. The air duct assembly routes filtered air to the
throttle body. Air enters the engine by to following steps:
1. Through the throttle body.
2. Into the intake manifold.
3. Through the cylinder head intake ports.
4. Into the cylinders.
General Description (Fuel Metering)
Deceleration Mode
The ECM reduces the amount of fuel injected when it
detects a decrease in the Accelerator position.
Fuel Injector
Fuel injector comprises the solenoid, hydraulic line, and
fuel line. Fuel injection is controlled by the continuity time
signal and continuity start timing signal from ECM to the
solenoid
ECM determines the running conditions of engine by
input signals such as engine speed. Accelerator throttle
valve opening, and engine coolant temperature, thereby
to send the solenoid the best suited signal to the engine
status. When current is carried to the solenoid, the
armature opens the poppet valve to alow high pressure oil
to run into the injector. Under the pressure of the oil, the
piston and plunger are depressed to compress the fuel in
the combustion chamber of the plunger. Specifically, the
pressure of the fuel compressed is increased by a piston
top/ plunger bottom area ratio over the pressure of high
pressure oil, thereby lifting the fuel nozzle end needle for
injecting fuel.
Fuel Metering System Components
The fuel metering system is made up of the following
parts:

The fuel injectors.

The intake throttle body.

The Accelerator position (AP) sensor

The ECM.

The crankshaft position (CKP) sensor.

The camshaft position (CMP) sensor.
Basic System Operation
Fuel is supplied through fuel filter to the fuel pump.
The fuel pump is installed to the oil pump, and fuel is
forced, through the fuel pump outlet, pipe and cylinder
head inside, into the fuel injector.
An orifice is provided at the rear fuel outlet of cylinder
head to control the pressure of oil.The injector is controlled by ECM which gives
opening/closing commands to the solenoid installed on
the top of the injector. Opening/closing operation of the
pressurized engine oil circuit of the injector controls fuel
injection quantity, fuel injection timing, etc.
A/C Clutch Diagnosis
A/C Request Signal
This signal tells the ECM when the A/C mode is selected
at the A/C control head. The ECM uses this to adjust the
idle speed.
Refer to
A/C Clutch Circuit Diagnosis for A/C wiring
diagrams and diagnosis for A/C electrical system.
General Description Exhaust Gas
Recirculation (EGR) System
EGR Purpose
The exhaust gas recirculation (EGR) system is use to
reduce emission levels of oxides of nitrogen (NOx). NOx
emission levels are caused by a high combustion
temperature. The EGR system lowers the NOx emission
levels by decreasing the combustion temperature.
The ECM uses information from the following sensors to
control EGR valve boost pressure.

ECT

ITP

Engine Speed

AP sensor

7A1±24
TRANSMISSION CONTROL SYSTEM (4L30±E)
Diagnostic Trouble Code (DTC)
Identification
DTC NUM-
BERDTC NAMEDTC TYPEªCHECK
TRANSº
P0218Transmission Fluid Over TemperatureD
P0560System Voltage MalfunctionCFlash
P0705Transmission Range Switch (Mode Switch) Illegal PositionD
P0706Transmission Range Switch (Mode Switch) PerformanceD
P0712Transmission Fluid Temperature Sensor Circuit Low Input
(TFT)D
P0713Transmission Fluid Temperature (TFT) Sensor Circuit High
InputD
P0719TCC Brake Switch Circuit High (Stuck ON)D
P0722Transmission Output Speed Sensor (OSS) Low InputCFlash
P0723Transmission Output Speed Sensor (OSS) IntermittentCFlash
P0730Transmission Incorrect Gear Ratio FlashCFlash
P0748Pressure Control Solenoid (PCS) (FORCE MOTOR) Circuit
ElectricalCFlash
P0753Shift Solenoid A ElectricalCFlash
P0758Shift Solenoid B ElectricalCFlash
P1790ROM Transmission Side Bad Check SumCFlash
P1792EEPROM Transmission Side Bad Check SumCFlash
P1835Kickdown Switch Always OND
P1850Brake Band Apply Solenoid MalfunctionD
P1860TCC Solenoid ElectricalD
DTC TYPEDEFINITION
CFlashing Check Trans on 1st failure
DNo lamps
NOTE: On the following charts, refer to the Powertrain
Control Module (PCM) section for the Wiring System, and
the Body and Accessories section for circuit diagram
details, parts location, and connector configuration.

WIRING SYSTEM 8DÐ1
BODY AND ACCESSORIES
WIRING SYSTEM
CONTENTS
Service Precautions . . . . . . . . . . . . . . . . . . . 8DÐ3
General Description . . . . . . . . . . . . . . . . . . . 8DÐ4Notes for Working on Electrical Items . . 8DÐ4
Symbols and Abbreviations . . . . . . . . . . . 8DÐ10
Parts for Electrical Circuit . . . . . . . . . . . . . 8DÐ12
Reading the Circuit Diagram . . . . . . . . . . 8DÐ21
Main Data and Specifications . . . . . . . . . . . 8DÐ24 Fuse, Fusible Link and Circuit Breaker Location . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ24
Relay Location . . . . . . . . . . . . . . . . . . . . . . 8DÐ27
Diode Location . . . . . . . . . . . . . . . . . . . . . . 8DÐ30
Grounding Point . . . . . . . . . . . . . . . . . . . . . 8DÐ33
Cable Harness Routing . . . . . . . . . . . . . . . 8DÐ45
Fuse Block Circuit . . . . . . . . . . . . . . . . . . . . . 8DÐ53 Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ54
Start and Charging . . . . . . . . . . . . . . . . . . . . 8DÐ67 General Description . . . . . . . . . . . . . . . . . . 8DÐ67
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ68
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ70
Powertrain Control Module (PCM) . . . . . . . 8DÐ80 General Description . . . . . . . . . . . . . . . . . . 8DÐ80
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ81
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ93
QOSIII (4JG2) . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ111 General Description . . . . . . . . . . . . . . . . . . 8DÐ111
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ112
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ114
QOS and EGR System (4JG2) . . . . . . . . . . . 8DÐ118 General Description . . . . . . . . . . . . . . . . . . 8DÐ118
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ119
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ122
Headlight and Fog Light . . . . . . . . . . . . . . . . 8DÐ127 General Description . . . . . . . . . . . . . . . . . . 8DÐ127
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ128
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ130
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ134
Rear Foglight . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ150 Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ151
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ152
Headlight Leveling . . . . . . . . . . . . . . . . . . . . 8DÐ153 General Description . . . . . . . . . . . . . . . . . . 8DÐ153
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ154
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ155
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ156
Clearance Light, Taillight and License Plate Light . . . . . . . . . . . . . . . . . . . . 8DÐ159 General Description . . . . . . . . . . . . . . . . . . 8DÐ159
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ160
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ163
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ168
Interior Illumination Light . . . . . . . . . . . . . . 8DÐ180 General Description . . . . . . . . . . . . . . . . . . 8DÐ180
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ181
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ185
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ192
Turn Signal Light and Hazard Warning Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ193
General Description . . . . . . . . . . . . . . . . . . 8DÐ193
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ194
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ197
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ202
Stoplight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ208 General Description . . . . . . . . . . . . . . . . . . 8DÐ208
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ209
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ212
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ216
Backup Light. . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ220 General Description . . . . . . . . . . . . . . . . . . 8DÐ220
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ221
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ223
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ227
Horn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ230 General Description . . . . . . . . . . . . . . . . . . 8DÐ230
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ231
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ232
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ235
Dome Light, Luggage Room Light, Courtesy Light and Map Light . . . . . . . . . . 8DÐ237
General Description . . . . . . . . . . . . . . . . . . 8DÐ237
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ238
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ240
Power Door Lock . . . . . . . . . . . . . . . . . . . . . . 8DÐ244 General Description . . . . . . . . . . . . . . . . . . 8DÐ244
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ245
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ250
Diagnosi s. . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ2 56
Power Window . . . . . . . . . . . . . . . . . . . . . . . 8DÐ261 General Description . . . . . . . . . . . . . . . . . . 8DÐ261
Circuit Diagram. . . . . . . . . . . . . . . . . . . . . . 8DÐ262
Parts Location . . . . . . . . . . . . . . . . . . . . . . . 8DÐ263
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ266
Cruise Control . . . . . . . . . . . . . . . . . . . . . . . . 8DÐ272

8DÐ4 WIRING SYSTEM
The chassis electrical system is a 12Ðvolt system with a
negative ground polarity.
Wire size are appropriate to respective circuits, and
classified by color. (The classification of harnesses by
color is shown on the circuit diagram for ease of harness
identification.)
The wire size is determined by load capacity and the
length of wire required.
The vehicle harnesses are: body harness, chassis
harness, engine room harness, instrument harness,
transmission harness, engine ECGI harness, dome light
harness, door harness, rear body harness, tailgate
harness, SRS harness and battery cables.
The harnesses are protected either by tape or corrugated
tube, depending on harness location.
The circuit for each system consists of the power source,
wire, fuse, relay, switch, load parts and ground, all of
which are shown on the circuit diagram.
In this section, each electrical device is classified by
system.
For major parts shown on the circuit based on the circuit
diagram for each system, a summary, diagnosis of
troubles and inspection procedures are detailed.
Notes for Working on Electrical
Items
Disconnecting the Battery Cable
1. All switches should be in the ÒOFFÓ position.
2. Disconnect the battery ground cable (2).
3. Disconnect the battery positive cable (1).
CAUTION: It is important that the battery ground
cable be disconnected first. Disconnecting the
battery positive cable first can result in a short circuit.
Connecting the Battery Cable
Follow the disconnecting procedure in the reverse order.CAUTION: Clean the battery terminal and apply a
light coat of grease to prevent terminal corrosion.
Disconnecting the Connector
Some connectors have a tang lock to hold the connectors
together during vehicle operation.
Some tang locks are released by pulling them towards
you (1).
Other tang locks are released by pressing them forward
(2).
Determine which type of tang lock is on the connector
being handled.
Firmly grasp both sides (male and female) of the
connector (3).
Release the tang lock and carefully pull the two halves of
the connector apart.
Never pull on the wires to separate the connectors (4).
2
1
General Description
1
2
3
4

8DÐ12 WIRING SYSTEM
Parts for Electrical Circuit
Wiring Ð Wire color
All wires have colorÐcoded insulation.
Wires belonging to a systemÕs main harness will have a
single color (1). Wires belonging to a systemÕs subcircuits
will have a colored stripe (2). Striped wires use the
following code to show wire size and colors.
Example: 0.5 G / R
Red (Stripe color)
Green (Base color)
Wire size (0.5 mm
2)
Wiring Ð Wire Color Coding
Abbreviations are used to indicate wire color within a circuit diagram.
Refer to the following table.
Color Coding Meaning Color Coding Meaning
B Black BR Brown
W White LG Light green
R Red GR Grey
G Green P Pink
Y Yellow LB Light blue
L Blue V Violet
O Orange
1
2

RESTRAINT CONTROL SYSTEM 9J1±2
Diagnostic Information
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.
Diagnostic Procedures
WARNING: T O AV O I D D E P L O Y M E N T W H E N
TROUBLESHOOTING THE SRS, DO NOT USE
ELECTRICAL TEST EQUIPMENT SUCH AS A
BATTERY±POWERED OR AC±POWERED
VOLTMETER, OHMMETER, ETC., OR ANY TYPE OF
ELECTRICAL EQUIPMENT OTHER THAN THAT
SPECIFIED IN THIS MANUAL. DO NOT USE A NON
POWERED, PROBE±TYPE TESTER.
INSTRUCTIONS IN THIS MANUAL MUST BE
FOLLOWED CAREFULLY, OTHERWISE PERSONAL
INJURY MAY RESULT.
The diagnostic procedures used in this section are
designed to aid in finding and repairing SRS problems.
Outlined below are the steps to find and repair SRS
problems quickly and effectively. Failure to carefully
follow these procedures may result in extended
diagnostic time, incorrect diagnosis and incorrect parts
replacement.
1.Perform The ªSRS Diagnostic System Checkº.
The ªSRS Diagnostic System Checkº should always
be the starting point of any SRS diagnostics. The
ªSRS Diagnostic System Checkº checks for proper
ªAIR BAGº warning lamp operation and checks for
SRS trouble codes using both ªFlash Codeº and
ªScan Toolº Methods.
2.Refer To The Proper Diagnostic Chart As Directed
By The ªSRS Diagnostic System Checkº.
The ªSRS Diagnostic System Checkº will lead you to
the correct chart to diagnose any SRS problems.
Bypassing these procedures may result in extended
diagnostic time, incorrect diagnosis and incorrect
parts replacement.
3.Repeat The ªSRS Diagnostic System Checkº
After Any Repair Or Diagnostic Procedures Have
Been Performed.
Preforming the ªSRS Diagnostic System Checkº after
all repair or diagnostic procedures will assure that the
repair has been made correctly and that no other
conditions exist.
Diagnostic Codes
The Sensing and Diagnostic Module (SDM) maintains a
history record of all diagnostic codes that have beendetected since the SRS codes were last cleared during
service.
1. Active Codes Ð Faults that are presently detected
this ignition cycle. Active codes are stored in RAM
(Random Access Memory).
2. History Codes Ð All faults detected since the last
time the history fault memory was cleared. History
codes are stored in EEPROM. (Electronically
Erasable Programmable Read only Memory)
How To Read Trouble Codes
All codes (Active and history) can be read (or cleared) by
using a scan tool or equivalent.
If a PDT is not available, have the vehicle serviced by
ISUZU dealer.
How To Clear Trouble Codes
Trouble codes can only be cleared by using a Scan Tool.
If a ªscan toolº is not available then inform the owner of the
stored codes and suggest that the codes are cleared
upon the next visit to an Isuzu dealership.
Scan Tool Diagnostics
A scan tool can be used to read current and history codes
and to clear all history codes after a repair is complete.
The scan tool must be updated to communicate with the
SRS through a memory card or a manufacturer's update
before it can be used for SRS diagnostics. To use the
scan tool, connect it to the DLC connector and turn the
ignition switch ªONº. Then follow the manufacturer's
directions for communication with the SRS. The scan tool
reads serial data from the SDM ªSerial Dataº output
(terminal 24) to the DLC connector (terminal 9).
Basic Knowledge Required
Before using this section of the Service Manual, there is
some basic knowledge which will be required. Without
this knowledge, you will have trouble using the diagnostic
procedures in this section. Use care to prevent harm or
unwanted deployment. Read all cautions in the service
manual and on warning labels attached to SRS
components.
Basic Electrical Circuits
You should understand the basic theory of electricity
including series and parallel circuits, and understand the
voltage drops across series resistors. You should know
the meaning of voltage (volts), current (amps), and
resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be
able to read and understand a wiring diagram.
ªFlash Codeº Diagnostics
Flash code diagnostics can be used to read active codes
and to determine if history codes are present but cannot
be used to clear codes or read history codes. Flash code
diagnostics is enabled by grounding by terminal 4
shorting to terminal 13 of the DLC connector with the
ignition switch ªONº. Grounding terminal 4 of the DLC
connector pulls the ªDiagnostics Requestº input (Terminal
1) of the SDM low and signals the SDM to enter the flash
code diagnostic display mode.