434 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
signal which the EOT sensor uses to produce an
analog voltage that indicates temperature.
The EOT changes resistance when exposed
to different tem p eratures. As oil temperature
decreases, the resistance of the thermistor increases.
This causes the signal v oltage to increase. As
oil temperature increases, the resistance of the
thermistor decreases. This causes the signal voltage
to decrease.
The EOT sensor provides a feedback signal to the
ECM indicating engine oil temperature. The ECM
monitors the EOT signal to control fuel quantity and
timing throughout the operating range of the engine.
The EOT signal allows the ECM to compensate for oil
viscosity variations due to temperat ure changes in the
operating environment, ensuring that adequate power
and torque are available for all operating conditions.
During engine operation, if the ECM recognizes that
the EOT signal is greater or less than the expected
value it will set a DTC.
Fast Idle Advance
Fast idle advance increases engine cold idle speed up
to 750 rpm (normally 700 rpm) for faster warm-up to
operating temperature. This is accomplished by the
ECM monitoring the EOT sensor input and adjusting
the fuel injector operation accordingly.
Low idle speed is increased proportionally when the
engine oil temperature is between 15 °C (59 °F) at
700 rpm to below -10 °C (14 °F) a t 750 r p m .
EOT Circuit Operation
Figure 449 EOT circuit diagram
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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