2004 ISUZU TF SERIES coolant temperature

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-5
ABBREVIATION CHARTS

Abbreviations Appellation
A/C Air conditioner
A/T Automatic transmission
ACC Accessory
BLK Black
BLU Blue
BRN Brown
CAN Controller Area Network
CEL Check engine lamp
CKP Crankshaft position
CMP Camshaft position
DLC Data link connector
DTC Diagnosis trouble code
DVM Digital voltage meter
ECM Engine control module
ECT Engine coolant temperature
EEPROM Electrically erasable & programmable read only memory
EGR Exhaust gas recalculation
GND Ground
GRY Gray
HO2S Heated Oxygen Sensor
IAT Intake air temperature
IAC Idle air control
IG Ignition
M/T Manual transmission
MAF Mass air flow
MIL Malfunction indicator lamp
OBD On-board diagnostic
ORN Orange
PNK Pink
PROM Programmable read only memory
RED Red
SW Switch
TPS Throttle position sensor
TCM Transmission control module
VCC Voltage Constant Control
VIO Violet
VSS Vehicle speed sensor
WHT White
WOT Wide open throttle
YEL Yellow

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-7











Legend
(1) Injector #1 Cylinder
(2) Injector #3 Cylinder
(3) Injector #5 Cylinder
(4) EGR Valve
(5) Ignition Coil #1 Cylinder
(6) Ignition Coil #3 Cylinder
(7) Ignition Coil #5 Cylinder
(8) Engine Coolant Temperature (ECT) Sensor












Legend
(1) Injector #2 Cylinder
(2) Injector #4 Cylinder
(3) Injector #6 Cylinder
(4) Idle Air Control (IAC) Valve
(5) Throttle Position Sensor
(6) Ignition Coil #2 Cylinder
(7) Ignition Coil #4 Cylinder
(8) Ignition Coil #6 Cylinder
(9) Canister Purge Solenoid Valve

6E-44 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Signal or Continuity Tester Position Pin
No.

B/Box
No.
Pin Function Wire
Color
Key SW
Off Key SW
On Engine
Idle Engine
2000rpmECM
Connection Range(+) (-)
A14 A14 No Connection - - - - - - - - -
A15 A15 No Connection - - - - - - - - -
A16 A16 No Connection - - - - - - - - -
A17 A17 No Connection - - - - - - - - -
A18 A18 No Connection - - - - - - - - -
A19 A19 Intake Air
Temperature
(IAT) Sensor
Signal YEL/
GRN Less than 1V0 deg. C: Approx. 3.5V / 20 deg. C: Approx.
2.5V / 40 deg. C: Approx. 1.6V / 60 deg. C:
0.9V / 80 deg. C: 0.6V Connect DC V A19 B39
A20 A20 No Connection - - - - - - - - -
A21 A21 Engine Coolant
Temperature
(ECT) Sensor
Signal BLU/
RED Less than 1V0 deg. C: Approx. 3.6V / 20 deg. C: Approx.
2.4V / 40 deg. C: Approx. 1.4V / 60 deg. C:
3.4V / 80 deg. C: 2.6V Connect DC V A21 A22
A22 A22 EGR Valve &
ECT Sensor
Ground YEL/
BLK Continuity
with ground - - - Connect Ohm A22 GND
A23 A23 Crank Position
(CKP) Sensor
Signal YEL - - Wave form or approx. 1.9V Connect AC V A23 A25
A24 A24 Crank Position
(CKP) Sensor &
EGR Valve +5V
Supply RED/
BLU Less than 1V Approx. 5V Connect DC V A24 A25
A25 A25 Crank Position
(CKP) Sensor
Ground YEL/
BLK Continuity
with ground - - - Connect Ohm A25 GND
A26 A26 No Connection - - - - - - - - -
A27 A27 No Connection - - - - - - - - -
A28 A28 ECM Main
Relay BLU/
RED While main
relay is
activated:
Less than 1V
Main relay is
not activated:
10-14V Less than 1V Connect DC V A28 GND
A29 A29 No Connection - - - - - - - - -
A30 A30 No. 5 Ignition
Coil RED/
YEL - - Wave form - - - -

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-51

GENERAL DESCRIPTION FOR ECM AND
SENSORS
Engine Control Module (ECM)


1 2
(1) A Port
(2) B Port


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

Fuel metering system

Ignition timing

On-board diagnostics for powertrain functions.

The ECM constantly observes the information from
various sensors. The ECM controls the systems tha
t
affect vehicle performance. And it performs the
diagnostic function of the system.
The function can recognize operational problems, and
warn to the driver through the check engine lamp, and
store diagnostic trouble code (DTC). DTCs identify the
problem areas to aid the technician in marking repairs.

The input / output devices in the ECM include analog to
digital converts, signal buffers, counters and drivers.
The ECM controls most components with electronic
switches which complete a ground circuit when turned
on.

Inputs (Operating condition read):

Battery voltage

Electrical ignition

Exhaust oxygen content

Mass air flow

Intake air temperature

Engine coolant temperature

Crankshaft position

Camshaft position

Throttle position

Vehicle speed

Power steering pressure

Air conditioning request on or off

EGR valve position

Outputs (Systems controlled):

Ignition control

Fuel control

Idle air control

Fuel pump

EVAP canister purge

Air conditioning

Diagnostics functions

The vehicle with automatic transmission, the
interchange of data between the engine control module
(ECM) and the transmission control module (TCM) is
performed via a CAN-bus system.
The following signals are exchanged via the CAN-bus:

ECM to TCM:

ECM CAN signal status

Engine torque

Coolant temperature

Throttle position

Engine speed

A/C status

CAN valid counter

TCM to ECM:

Ignition timing retard request

Garage shift status

CAN valid counter

6E-52 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Mass Air Flow (MAF) Sensor & Intake Air
Temperature (IAT) Sensor





The MAF sensor is part of the intake air system.
It is fitted between the air cleaner & throttle body and
measure the mass air flowing into the engine.
The MAF sensor uses a hot wire element to determine
the amount of air flowing into the engine. (The wire
temperature reaches to 170 - 300C)
The MAF sensor assembly consist of a MAF senso
r
element and an intake air temperature sensor that are
both exposed to the air flow to be measured.
The MAF sensor element measures the partial air mass
through a measurement duct on the sensor housing.
Using calibration, there is an extrapolation to the entire
mass air flow to the engine.


















The IAT sensor is a thermistor. A temperature changes
the resistance value. And it changes voltage. In othe
r
words it measures a temperature value. Low air
temperature produces a high resistance.
The ECM supplies 5 volts signal to the IAT senso
r
through resisters in the ECM and measures the voltage.
The signal voltage will be high when the air temperature
is cold, and it will be low when the air temperature is
hot. Throttle Position Sensor (TPS)





1
2
(1) Throttle Position Sensor (TPS)
(2) Idle Air Control Valve (IACValve)


The TPS is a potentiometer connected to throttle shaf
t
on the throttle body.
The engine control module (ECM) monitors the voltage
on the signal line and calculates throttle position. As the
throttle valve angle is changed when accelerator pedal
moved. The TPS signal also changed at a moved
throttle valve.
As the throttle valve opens, the output
increases so that the output voltage should be high.

The throttle body has a throttle plate to control the
amount of air delivered to the engine. Engine coolant is
directed through a coolant cavity in the throttle body to
warm the throttle valve and to prevent icing.
Charac teristic of IA T Sens or
10 100 1000 10000 100000-3010 50 90130Temper atur e (

)
Resistance (Ω)

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-53
Idle Air Control (IAC) Valve








Step
CoilAB CD
Coil A High
(EC M B13)On On
Coil A Low
(EC M B16)On On
Coil B High
(EC M B14)On On
Coil B Low
(EC M B17)On On

(IAC Valve Close Direction)
(IAC Valve Open Direction)



The idle air control valve (IAC) valve is two directional
and gives 2-way control. It has a stepping moto
r
capable of 256 steps, and also has 2 coils. With power
supply to the coils controlled steps by the engine control
module (ECM), the IAC valve's pintle is moved to adjus
t
idle speed, raising it for fast idle when cold or there is
extra load from the air conditioning or power steering.
By moving the pintle in (to decrease air flow) or out (to
increase air flow), a controlled amount of the air can
move around the throttle plate. If the engine speed is
too low, the engine control module (ECM) will retract the
IAC pintle, resulting in more air moving past the throttle
plate to increase the engine speed.
If the engine speed is too high, the engine control
module (ECM) will extend the IAC pintle, allowing less
air to move past the throttle plate, decreasing the
engine speed.

The IAC pintle valve moves in small step called counts.
During idle, the proper position of the IAC pintle is
calculated by the engine control module (ECM) based
on battery voltage, coolant temperature, engine load,
and engine speed.
If the engine speed drops below a specified value, and
the throttle plate is closed, the engine control module
(ECM) senses a near-stall condition. The engine control
module (ECM) will then calculate a new IAC pintle valve
position to prevent stalls. If the IAC valve is disconnected and reconnected with
the engine running, the idle speed will be wrong. In this
case, the IAC must be reset. The IAC resets when the
key is cycled "On" then "Off". When servicing the IAC, i
t
should only be disconnected or connected with the
ignition "Off".
The position of the IAC pintle valve affects engine start-
up and the idle characteristic of the vehicle.
If the IAC pintle is fully open, too much air will be
allowed into the manifold. This results in high idle
speed, along with possible hard starting and lean
air/fuel ratio.

Camshaft Position (CMP) Sensor








12
(1) Camshaft Position (CMP) Sensor
(2) EGR Valve


With the use of sequential multi-point fuel injection, a
hall element type camshaft position (CMP) is adopted to
provide information to be used in making decisions on
injection timing to each cylinder. It is mounted on the
rear of the left-hand cylinder head and sends signals to
the ECM.
One pulse is generated per two rotations of crankshaft.

6E-54 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Crankshaft Position (CKP) Sensor





The crankshaft position (CKP) sensor, which sends a
signal necessary for deciding on injection timing to the
ECM, is mounted on the right-hand side of the cylinde
r
block.
The crankshaft has a 58 teeth press-fit timing disc, from
which the CKP sensor reads the position of the
crankshaft at all the times. It converts this to an
electrical signal, which it sends to the ECM.
Of the 58 teeth, 57 have a base with of 3°, and are
evenly spaced, but tooth No. 58 is 15° wide at its based
to serve as a timing mark, allowing the sensor to repor
t
the standard crankshaft position.
Using the 58 X signals per rotation and the timing-mark
signal sent by the CKP sensor, the ECM is able to
accurately calculate engine speed and crank position.
Also, the position of each cylinder is precisely known by
the ECM from signals sent by the camshaft position
(CMP) sensor, so the sequential multi-point fuel
injection can be controlled with accuracy.

The 58 X signals are converted by the ECM into a
retangle wave signal. This converted signal is sent from
the ECM terminal B12 to the tachometer and transfe
r
case control module (TCCM) terminal 15 (if 4WD
model).
Engine Coolant Temperature (ECT) Sensor




















The ECT sensor is a thermistor. A temperature
changes the resistance value. And it changes voltage.
In other words it measures a temperature value. It is
installed on the coolant stream. Low coolan
t
temperature produces a high resistance.
The ECM supplies 5 volts signal to the ECT senso
r
through resisters in the ECM and measures the voltage.
The signal voltage will be high when the engine
temperature is cold, and it will be low when the engine
temperature is hot.

Characteris tic of ECT Sens or
10 100 1000 10000 100000-3010 50 90130Temperature (

)
Resistance (Ω)

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-57
Starting Mode
When the ignition is first turned "ON," the ECM
energizes the fuel pump relay for two seconds to allo
w
the fuel pump to build up pressure. The ECM then
checks the engine coolant temperature (ECT) senso
r
and the throttle position sensor to determine the proper
air/fuel ratio for starting.
The ECM controls the amount of fuel delivered in the
starting mode by adjusting how long the fuel injectors
are energized by pulsing the injectors for very short
times.

Fuel Metering System Components
The fuel metering system is made up of the following
parts.

Fuel injector

Throttle Body

Fuel Rail

Fuel Pressure regulator

ECM

Crankshaft position (CKP) sensor

Camshaft position (CMP) sensor

Idle air control valve

Fuel pump

Fuel Injector
The sequential multi-port fuel injection fuel injector is a
solenoid operated device controlled by the ECM. The
ECM energizes the solenoid, which opens a valve to
allow fuel delivery.
The fuel is injected under pressure in a conical spray
pattern at the opening of the intake valve. Excess fuel
not used by the injectors passes through the fuel
pressure regulator before being returned to the fuel
tank.

Fuel Pressure Regulator
The fuel pressure regulator is a diaphragm-operated
relief valve mounted on the fuel rail with fuel pump
pressure on one side and manifold pressure on the
other side. The fuel pressure regulator maintains the
fuel pressure available to the injector at three times
barometric pressure adjusted for engine load. It may be
serviced separate.
If the pressure is too low, poor performance and a DTC
P0131, P0151, P0171, P0174, P1171 or P1174 will be
the result. If the pressure is too high, excessive odo
r
and/or a DTC P0132, P0152, P0172 or P0175 will be
the result. Refer to Fuel System Diagnosisfo
r
information on diagnosing fuel pressure conditions.
Fuel Rail
The fuel rail is mounted to the top of the engine and
distributes fuel to the individual injectors. Fuel is
delivered to the fuel inlet tube of the fuel rail by the fuel
lines. The fuel goes through the fuel rail to the fuel
pressure regulator. The fuel pressure regulato
r
maintains a constant fuel pressure at the injectors.
Remaining fuel is then returned to the fuel tank.







055RV009
Fuel Pump Electrical Circuit
When the key is first turned "ON," the ECM energizes
the fuel pump relay for two seconds to build up the fuel
pressure quickly. If the engine is not started within two
seconds, the ECM shuts the fuel pump off and waits
until the engine is cranked. When the engine is cranked
and the 58 X crankshaft position signal has been
detected by the ECM, the ECM supplies 12 volts to the
fuel pump relay to energize the electric in-tank fuel
pump.
An inoperative fuel pump will cause a "no-start"
condition. A fuel pump which does not provide enough
pressure will result in poor performance.

Camshaft Position (CMP) Sensor Signal
The ECM uses this signal to determine the position o
f
the number 1 piston during its power stroke, allowing
the ECM to calculate true sequential multiport fuel
injection. Loss of this signal will set a DTC P0341. If the
CMP signal is lost while the engine is running, the fuel
injection system will shift to a calculated sequential fuel
injection based on the last fuel injection pulse, and the
engine will continue to run. The engine can be restarted
and will run in the calculated sequential mode as long
as the fault is present, with a 1-in-6 chance of being
correct.