Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 880

6E–249

3.2L ENGINE DRIVEABILITY AND EMISSIONS

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–250 3.2L ENGINE DRIVEABILITY AND EMISSIONS

General Description (ECM and
Sensors)

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 reference signal.

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 before turning “ON” the A/C clutch.  The A/C
compressor will be inoperative if this signal is not
available to the ECM.
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 58X
reference pulses which the ECM 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 ECM.  The ECM uses this signal as a “syncpulse” to
trigger the injectors in the proper sequence.  The ECM

uses the CMP signal to indicate the position of the #1
piston during its power stroke.  This allows the ECM to
calculate true sequential fuel injection (SFI) mode of
operation.  If the ECM 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 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 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 P0118.

6E–251

3.2L 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 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.

Fuel Control Heated Oxygen Sensors

The fuel control heated oxygen sensor is 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 a Tech 2.  By
monitoring the voltage output of the oxygen sensor, the
ECM 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.

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 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 IAT sensor signal is used
to adjust spark timing according to the incoming air
density.
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–252 3.2L ENGINE DRIVEABILITY AND EMISSIONS

060RW034

Mass Air Flow (MAF) Sensor

The mass air flow (MAF) sensor measures the difference
between the volume and the quantity of air that enters the
engine.  “Volume” means the size of the space to be filled.
“Quantity” means the number of air molecules that will fit
into the space.  This information is important to the ECM
because heavier, denser air will hold more fuel than
lighter, thinner air.  The ECM adjusts the air/fuel ratio as
needed depending on the MAF value.  The Tech 2 reads
the MAF value and displays it in terms of grams per
second (gm/s).  At idle, the Tech 2 should read between
4-7 gm/s on a fully warmed up engine.  Values should
change quickly on acceleration.  Values should remain
stable at any given RPM.  A failure in the MAF sensor or
circuit will set DTC P0101, DTC P0102, or DTC P0103.

060RW023

Barometric Pressure (BARO) Sensor

The barometric pressure (BARO) sensor responds to
changes in intake manifold pressure (vacuum).

D

Barometric pressure (BARO).

If the ECM detects a voltage that is lower than the
possible range of the BARO sensor, DTC P0107 will be
set.  A signal voltage higher than the possible range of the
sensor will set DTC P0108.  The ECM can detect a shifted
BARO sensor.  The ECM compares the BARO sensor
signal to a calculated BARO based on throttle position
and various engine load factors.

060RW033

Engine Control Module (ECM)

The engine control module (ECM) is located on the
common chamber. The ECM controls the following:

D

Fuel metering system.

D

Ignition timing.

D

On-board diagnostics for powertrain functions.

The ECM constantly observes the information from
various sensors.  The ECM controls the systems that
affect vehicle performance.  The ECM performs the
diagnostic function of the system.  It can recognize
operational problems, alert the driver through the MIL
(Service Engine Soon lamp), and store diagnostic trouble
codes (DTCs).  DTCs identify the problem areas to aid the
technician in making repairs.

ECM Function

The ECM supplies either 5 or 12 volts to power various
sensors or switches.  The power is supplied through
resistances in the ECM which are so high in value that a
test light will not light when connected to the circuit.  In
some cases, even an ordinary shop voltmeter will not give
an accurate reading because its resistance is too low.
Therefore, a digital voltmeter with at least 10 megohms
input impedance is required to ensure accurate voltage
readings. Tool J 39200 meets this requirement.  The ECM
controls output circuits such as the injectors, IAC, cooling
fan relays, etc., by controlling the ground or the power