International VT 365 Service Manual page 47

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.
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
ENGINE SYSTEMS
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.
EGES295-2
Follow all warnings, cautions, and notes.
© 2006 International Truck and Engine Corporation
43