Isuzu Trooper (1998-2002 year). Manual - part 355

6E–333

ENGINE DRIVEABILITY AND EMISSIONS

2. Use tool J 28742-A or the equivalent to remove the

pin and the sleeve terminals.  Push on J 28742-A to
release.

NOTE: Do the use an ordinary pick or the terminal may
be bent or deformed.  Unlike standard blade terminals,
these terminals cannot be straightened after they have
been improperly bent.

071

3. Cut the wire immediately behind the cable seal.

072

Installation Procedure

Make certain the connectors are properly seated and all
of the sealing rings are in place when you reconnect the
leads.  The secondary lock hinge provides a backup
locking feature for the connector.  The secondary lock
hinge is used for added reliability.  This flap should retain
the terminals even if the small terminal lock tangs are not
positioned properly.
Do not replace the Weather-Pack connections with
standard connections.  Read the instructions provided
with the Weather-Pack connector and terminal packages.
1. Replace the terminal.

2. Slip the new seal onto the wire.
3. Strip 5 mm (0.2”) of insulation from the wire.
4. Crimp the terminal over the wire and the seal.

073

5. Push the terminal and the connector to engage the

locking tangs.

070

6. Close the secondary locking hinge.

Com-Pack III

General Information

The Com-Pack III terminal looks similar to some
Weather-Pack terminals.  This terminal is not sealed and
is used where resistance to the environment is not
required.  Use the standard method when repairing a
terminal.  Do not use the Weather-Pack terminal tool J
28742-A or equivalent.  These will damage the terminals.

Metri-Pack

Tools Required

J 35689 Terminal Remover

6E–334

ENGINE DRIVEABILITY AND EMISSIONS

Removal Procedure

Some connectors use terminals called Metri-Pack Series
150.  These may be used at the engine coolant
temperature (ECT) sensor.
1. Slide the seal (1) back on the wire.
2. Insert the J 35689 tool or equivalent (3) in order to

release the terminal locking tang (2).

060

3. Push the wire and the terminal out through the

connector.  If you reuse the terminal, reshape the
locking tang.

Installation Procedure

Metri-Pack terminals are also referred to as “pull-to-seat”
terminals.
1. In order to install a terminal on a wire, the wire must be

inserted through the seal (2) and through the
connector (3).

2. The terminal (1) is then crimped onto the wire.

061

3. Then the terminal is pulled back into the connector to

seat it in place.

6E–335

ENGINE DRIVEABILITY AND EMISSIONS

General Description

General Description (PCM and
Sensors)

58X Reference PCM Input

The powertrain control module (PCM) uses this signal
from the crankshaft position (CKP) sensor to calculate
engine RPM and crankshaft position at all engine speeds.
The PCM also uses the pulses on this circuit to initiate
injector pulses.  If the PCM receives no pulses on this
circuit, DTC P0337 will set.  The engine will not start and
run without using the 58X reference signal.

A/C Request Signal

This signal tells the PCM when the A/C mode is selected
at the A/C control head.  The PCM uses this to adjust the
idle speed before turning “ON” the A/C clutch.  The A/C
compressor will be inoperative if this signal is not
available to the PCM.
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 powertrain control module (PCM) to calculate
the ignition sequence.  The CKP sensor initiates the 58X
reference pulses which the PCM uses to calculate RPM
and crankshaft position.
Refer to 

Electronic Ignition System for additional

information.

0013

Camshaft Position (CMP) Sensor and
Signal

The camshaft position (CMP) sensor sends a CMP signal
to the PCM.  The PCM uses this signal as a “sync pulse” to

trigger the injectors in the proper sequence.  The PCM
uses the CMP signal to indicate the position of the #1
piston during its power stroke.  This allows the PCM to
calculate true sequential fuel injection (SFI) mode of
operation.  If the PCM detects an incorrect CMP signal
while the engine is running, DTC P0341 will set.  If the
CMP signal is lost while the engine is running, the fuel
injection system will shift to a calculated sequential fuel
injection mode based on the last fuel injection pulse, and
the engine will continue to run.  As long as the fault is
present, the engine can be restarted.  It will run in the
calculated sequential mode with a 1-in-6 chance of the
injector sequence being correct.
Refer to 

DTC P0341 for further information.

0014

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 PCM supplies a 5-volt signal to the ECT sensor
through  resistors in the PCM 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
PCM calculates the engine coolant temperature.  Engine
coolant temperature affects most of the systems that the
PCM controls.
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 coolant
temperature and intake air temperature displays should
be close to each other.  A hard fault in the engine coolant
sensor circuit will set DTC P0177 or DTC P0118.  An
intermittent fault will set a DTC P1114 or P1115.

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ENGINE DRIVEABILITY AND EMISSIONS

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 PCM.  The EEPROM
contains the program and the calibration information that
the PCM needs to control powertrain operation.
Unlike the PROM used in past applications, the EEPROM
is not replaceable.  If the PCM is replaced, the new PCM
will need to be programmed.  Equipment containing the
correct program and calibration for the vehicle is required
to program the PCM.

Fuel Control Heated Oxygen Sensors

The fuel control heated oxygen sensors (Bank 1 HO2S 1
and Bank 2 HO2S 1) are mounted in the exhaust stream
where they can monitor the oxygen content of the exhaust
gas.  The oxygen present in the exhaust gas reacts with
the sensor to produce a voltage output.  This voltage
should constantly fluctuate from approximately 100 mV to
900 mV.  The heated oxygen sensor voltage can be
monitored with Tech 2.  By monitoring the voltage output
of the oxygen sensor, the PCM calculates the pulse width
command for the injectors to produce the proper
combustion chamber mixture.

D

Low HO2S voltage is a lean mixture which will result in
a rich command to compensate.

D

High HO2S voltage is a rich mixture which will result in
a lean command to compensate.

An open Bank 1 HO2S 1 signal circuit will set a DTC
P0134 and Tech 2 will display a constant voltage between
400-500 mV.  A constant voltage below 300 mV in the
sensor circuit (circuit grounded) will set DTC P0131.  A
constant voltage above 800 mV in the circuit will set DTC
P0132.  Faults in the Bank 2 HO2S 1 signal circuit will
cause DTC 0154 (open circuit), DTC P0151 (grounded
circuit), or DTC P0152 (signal voltage high) to set.

0012

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 PCM supplies a 5-volt signal to the sensor

through a resistor in the PCM 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 PCM calculates the
incoming air temperature.  The IAT sensor signal is used
to adjust spark timing according to the incoming air
density.
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.