1995 ISUZU TROOPER Workshop Manual

DRIVEABILITY AND EMISSIONS 6E2-17
I OPERATING CONDITIONS READ I
I SYSTEMS CONTROLLED I
• Air Conditioning "On" or "Off" • Evaporative Emission Canister
• Engine Coolant Temperature Purge
• Crankshaft Position • Exhaust Gas Recirculation
• Exhaust Heated Oxygen Sensor • Ignition Control
• Electronic Ignition Reference • Fuel Control
• Crankshaft Position
ENGINE • Idle Air Control
• Engine Speed (RPM} CONTROL • Electric Fuel Pump
• Manifold Absolute Pressure (MAP)
MODULE • Air Conditioning
• Battery Positive Voltage (ECM) • Diagnostics
• Throttle Position Sensor • Malfunction Indicator Lamp
• Vehicle Speed Sensor • Diagnostic Test Terminal
• Fuel Pump Voltage • Data Output
• Power Steering Pressure • Transmission Control Module
• Intake Air Temperature • Knock Sensor (DOHC)
• Differential Pressure • Induction Air Control Plate System
• Knock Sensor (DOHC)
(DOHC)
• Exhaust Gas Recirculation Vacuum
• Air Conditioning High Side Pressure
Fig. 6E2-3
ENGINE CONTROL MODULE (ECM) AND
SENSORS
This Section describes the Engine Control Module
(ECM) and the information sensors in the system.
Figure (Fig. 6E2-3) shows the operating conditions
which the
ECM may read and the systems thatthe ECM
may control.
FUEL CONTROL SYSTEM
The ECM controls the air/fuel delivery to the combus­
tion chamber by
controlling the fuel flow through the
injector(s).
ELECTRIC FUEL PUMP (IN-TANK)
The in-tank fuel pump is controlled by the ECM. When
ignition is turned on, the
pump will run for 2 seconds,
then stop
unless the engine is cranking or running.
EVAPORATIVE EMISSION (EVAP) CONTROL
SYSTEM
This system has a canister which stores fuel vapor
from the fuel tank. The fuel vapor is removed from the
canister and consumed in the
normal combustion
process when the engine
is running.
IGNITION CONTROL (IC)
This system is controlled by the ECM which controls
spark advance (timing) and is used on all engines.
EXHAUST GAS RECIRCULATION (EGR)
The exhaust gas recirculation system uses ECM
controlled valve to feed a small amount of exhaust gas
back into the intake
manifold to control formation of
NOx.
AIR CONDITIONING (A/C) CLUTCH CONTROL
The ECM may control the air conditioning clutch on the
compressor
to improve idle quality.
POSITIVE CRANKCASE VENTILATION (PCV)
The PCV system passes crankcase vapors into the
intake
manifold. This system is not controlled by the
ECM and is used on all engines.

6E2-18 DRIVEABILITV AND EMISSIONS
TOOLS NEEDED TO SERVICE THE SVSJEM
The system requires a data link connector read-out (Scan) tool, tachometer, test light, ohmmeter, digital voltmeter
with 10 megohms impedance (J-39200), vacuum gage and jumper wires for diagnosis. A test light or voltmeter
must be used when specified in the procedures. They must NOT be interchanged. For more complete information
on the operation
of these tools, see the manufacturer's instructions.
Voltmeter
Voltage position measures amount of voltage when
connected in
parallel to an existing circuit. A digital
voltmeter
with 10 megohm input impedance is used
because this type
of meter will not load down the
circuit and
result in faulty readings. Some circuits
require accurate
low voltage readings, and some
circuits in the engine
control module have a very high
resistance.
Digital multimeter: J-39200 or equivalent
Fig. 6E2-4
Ammeter
When used as ammeter, this meter also accurately
measures extremely low current flow. Refer to meter
instructions
for more information.
• Selector must be set properly for both function
and range.
DC is used for most automotive
measurements.
Digital multimeter: J-39200 or equivalent
Ohmmeter
Measures resistance of circuit directly in ohms.
Refer to meter instructions
for more information.
• OL Display in all ranges indicates open circuit.
• Zero display in all ranges indicates a short circuit.
• Intermittent connection in circuit may be
indicated by digital reading that will not stabilize
on circuit.
• Range Switch
200 -Reads ohms
directly
2K, 20K, 200K -Reads ohms in thousands
2M and 20M -Reads ohms in
millions
Digital multimeter:
J-39200 or equivalent
Vacuum pump (20 in. hydragyrum minimum)
Use gage to monitor manifold engine vacuum and the
hand pump to check vacuum sensors,
solenoids and
valves.
Vacuum pump: J-23738
Fig. 6E2-5
Unpowered test light
Used to check wiring for complete circuit and short to
ground
or voltage.
Unpowered test light: J-34142-A
Fig. 6E2-6
•

Tachometer
Use inductive trigger signal pickup type to check
revolution per minute.
Fig. 6E2-7
Multiport fuel injection (MFI) diagnostic kit
Used to diagnose MFI systems.
The kit
includes:
• Fuel
Pressure Gage-to check fuel pump pressure
and compare injector pressure
drop for equal fuel
distribution.
• Injector Test Light-to check electrical circuit to an
injector.
• Injector Test-to energize each fuel injector for a
precise
amount of time to perform injector
balance test in CHART C-2A by checking each
injector's pressure
drop using pressure gage.
MFI test kit: J-34730-8
Fuel pressure gage
Used to check and monitor fuel line pressure of port
fuel system.
MFI test kit: J-34730-8
Injector test light
Used to check electrical circuit to a port fuel injector.
MFI test kit: J-34730-8
Injector tester
Used to energize each fuel injector for a precise
amount of time to perform injector balance test in
CHART C-2A by checking each injector's pressure drop
using pressure gage.
MFI test kit: J-34730-8
DRIVEABILITY AND EMISSIONS 6E2-19
Fig. 6E2-8
Spark tester
Use to check available secondary ignition voltage.
Also called
an ST125.
Spark
tester: J-26792
Fig. 6E2-9
Connector test adapter kit
Used to make electrical test connections in current
Weather Pack, Metri-Pack and Micro-Pack
style
terminals.
Terminal test adapter kit: J-35616
Fig. 6E2-10

6E2-20 DRIVEABILITV AND EMISSIONS
Circuit tester
Used to check all relays and solenoids before
connecting them to a
new engine control module.
Measures the circuit resistance and indicates pass or
fail via green or red LED. Amber LED indicates current
polarity. Can also be used as a non-powered continuity
checker.
Engine
control module circuit tester: J-34636
Fig.
6E2-11
Metri-pack terminal remover
Used to remove 150 series Metri-Pack "pull-to-seat"
terminals
from connectors.
Terminal remover: J-35689-A
Fig. 6E2-12
Idler air control (lAC) system driver
Used to test lAC motor for correct functioning and
proper response to commands.
lAC system driver: J-37027-A
Fig. 6E2-13
Weather pack terminal remover
Used to remove Terminals from Weather Pack
connectors.
Weather pack terminal remover: J-28742-A
Fig. 6E2-13
•