Engine International VT365. Manual - part 11

ENGINE SYSTEMS

The EGR drive module receives the desired EGR
valve position from the ECM across the CAN 2
datalink to activate the EGR valve for exhaust gas
recirculation.

The EGR drive module provides feedback to the ECM
on the valve position. When an EGR control error is
detected, the EGR drive module sends a message to
the ECM and a DTC is set.

Injection Pressure Regulator (IPR)

The IPR valve controls pressure in the Injection
Control Pressure (ICP) system. The IPR valve is a
variable position valve controlled by the ECM. This
regulated pressure actuates the fuel injectors. The
valve position is controlled by switching the ground
circuit in the ECM. The voltage source is supplied by
the ignition switch.

Glow plug relay

The ECM activates the glow plug relay. The relay
delivers V

BAT

to the glow plugs for up to 120 seconds,

depending on ambient temperature and altitude. The
ground circuit is supplied directly from the battery
ground at all times.

The relay is controlled by

switching on a voltage source from the ECM.

Injection Drive Module (IDM)

Figure 33 Injection Drive Module (IDM)

The IDM has three functions:

•

Electronic distributor for injectors

•

Power source for injectors

•

IDM and injector diagnostics

Electronic distributor for injectors

The IDM distributes current to the injectors. The IDM
controls fueling to the engine by sending high voltage
pulses to the OPEN and CLOSE coils of the injector.
The IDM uses information from the ECM to determine
the timing and quantity of fuel for each injector.

The ECM uses CMP and CKP input signals to
calculate engine speed and position.

The ECM

conditions both input signals and supplies the IDM
with CMP and CKP output signals. The IDM uses
CMP and CKP output signals to determine the correct
sequence for injector firing.

The ECM sends information (fuel volume, EOT, and
ICP) through the CAN 2 link to the IDM; the IDM uses
this information to calculate the injection cycle.

Injector Power Source

The IDM creates a constant 48 volt (DC) supply to
all injectors by making and breaking a 12 volt source
across a coil in the IDM. The 48 volts created by the
collapsed field is stored in capacitors until used by the
injectors.

The IDM controls when the injector is turned on and
how long the injector is active. The IDM first energizes
the OPEN coil, then the CLOSE coil. The low side
driver supplies a return circuit to the IDM for each
injector coil (open and close). The high side driver
controls the power supply to the injector. During each
injection event, the low and high side drivers are
switched on and off for each coil.

IDM and injector diagnostics

The IDM determines if an injector is drawing enough
current. The IDM sends a fault to the ECM, indicating
potential problems in the wiring harness or injector,
and the ECM will set a DTC. The IDM also does self
diagnostic checks and sets a DTC to indicate failure
of the IDM.

On demand tests can be done using the Electronic
Service Tool (EST). The EST sends a request to the
ECM, the ECM sends a request to the IDM to do a

ENGINE SYSTEMS

test. Some tests generate a DTC when a problem
exists. Other tests require the technician to evaluate
parameters, if a problem exists.

Engine and Vehicle Sensors

Figure 34

Engine and Vehicle Sensors

Electronic Control Module
(ECM)

Engine Oil Temperature (EOT)

Engine Coolant Temperature
(ECT)

Manifold Air Temperature (MAT)

Intake Air Temperature (IAT)

Injection Control Pressure (ICP)

Exhaust Back Pressure (EBP)

Engine Oil Pressure (EOP)

Manifold Absolute Pressure
(MAP)

10. Camshaft Position (CMP)
11. Crankshaft Position (CKP)
12. Vehicle Speed Sensor (VSS)
13. Barometric Absolute Pressure

(BAP)

14. Driveline Disengagement Switch

(DDS)

15. Engine Coolant Level (ECL)
16. Exhaust Gas Recirculation

(EGR) drive module

17. Accelerator Position Sensor

(APS)

18. EGR valve

ENGINE SYSTEMS

Figure 35

Thermistor

Thermistors

•

ECT

•

EOT

•

IAT

•

MAT

A thermistor sensor changes electrical resistance as
temperature changes. Resistance in the thermistor
decreases as temperature increases, and increases
as temperature decreases. Thermistors work with a
resistor that limits current in the ECM to form a voltage
signal matched with a temperature value.

The top half of the voltage divider is the current limiting
resistor that is internal to the ECM. A thermistor sensor
has two electrical contacts: signal return and ground.
The output of a thermistor sensor is a non-linear
analog signal.

Engine Coolant Temperature (ECT)

The ECT sensor detects engine coolant temperature.

The ECT signal is monitored by the ECM for operation
of the instrument panel temperature gauge, coolant
temperature compensation, optional Engine Warning
Protection System (EWPS), glow plugs, and the wait
to start lamp. The ECM will use ECT sensor input as
a backup, if EOT sensor values are out of range.

The ECT sensor is installed in the left side of the front
cover.

Engine Oil Temperature (EOT)

The EOT sensor detects engine oil temperature.

The EOT signal is monitored by the ECM to control
EGR, VGT, and for engine fueling calculations
throughout the operating range of the engine. The
EOT signal allows the ECM and IDM to compensate
for differences in oil viscosity, due to temperature
changes.

The EOT sensor is installed in the oil filter base.

Intake Air Temperature (IAT)

The IAT signal is monitored by the ECM to control
timing and fuel rate during cold starts.

The IAT sensor is chassis mounted in the air filter
housing.

Manifold Air Temperature (MAT)

The

MAT

sensor

detects

intake

manifold

air

temperature.

The MAT signal is monitored by the ECM for EGR
operation.

The MAT sensor is installed in the right front of the
intake manifold.

ENGINE SYSTEMS

Figure 36

Variable capacitance sensor

Variable capacitance sensors

•

BAP

•

EBP

•

EOP

•

ICP

•

MAP

Variable capacitance sensors measure pressure. The
pressure measured is applied to a ceramic material.
The pressure forces the ceramic material closer to a
thin metal disk. This action changes the capacitance
of the sensor.

The sensor is connected to the ECM by three wires:

•

REF

•

Signal return

•

Signal ground

The sensor receives the V

REF

and returns an analog

signal voltage to the ECM. The ECM compares the
voltage with pre-programmed values to determine
pressure.

The operational range of a variable capacitance
sensor is linked to the thickness of the ceramic disk.
The thicker the ceramic disk the more pressure the
sensor can measure.

Barometric Absolute Pressure (BAP)

The BAP sensor detects altitude.

The BAP sensor provides information to the ECM
for control of fuel quantity, fuel timing, glow plug
operation, and adjustment of the VGT to compensate
for density changes.

The BAP sensor is mounted behind the instrument
panel.

Engine Oil Pressure (EOP)

The EOP sensor detects engine oil pressure.

The EOP signal is monitored by the ECM for operation
of the instrument panel pressure gauge and optional
EWPS.

The EOP sensor is installed in the oil filter base.

Exhaust Back Pressure (EBP)

The EBP sensor measures exhaust back pressure
before the turbocharger.

The EBP sensor provides feedback to the ECM for
closed loop control of the VGT and for EGR position
calculations.

The EBP sensor is mounted on a bracket on the left
side of the engine below the ECM.

Injection Control Pressure (ICP)

The ICP sensor,

a micro-strain gauge sensor,

measures injection control pressure.

The ICP signal is monitored by the ECM for closed
loop control of the IPR valve. The ICP signal is also
used by the IDM for engine fueling calculations.

The ICP sensor is installed in the right high-pressure
oil rail.

Manifold Absolute Pressure (MAP)

The MAP sensor detects intake manifold boost
pressure.

The MAP signal is monitored by the ECM for EGR
position and engine fueling calculations.

The MAP sensor is installed in the top front of the
intake manifold.

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