398 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
EFAN Control (Engine Fan Control)
Figure 433 Function diagram for EFAN
The function diagram for EFAN includes the following:
• Electronic Control Module (ECM)
• Engine Coolant Temperature (ECT) sensor
• Intake Air Temperature (IAT) sensor
• Electronic S ystem C on troller (ESC)
• Engine fan relay
Function
The EFAN control provides ON/OFF control of
theenginecoolingsystemfan. TheECMcanbe
programmed to set and monitor limits for engine
coolant temperature, intake air temperature, engine
mode selection (operating or diagnostic).
EFAN is accessible with the EST. Fan on and off
temperature can be programmed by technician, but
the mode of operation must be done by Tech Services.
The purpose of the engine fan control is to provide
the correct logic to determine when the fan should
be turned on or off by energizing/deenergizing the fan
drive relay. The purpose of the engine fan is to allow a
higher air flow for heat exchange between the radiator
and the ambient air when needed.
Engine Fan Control – This parameter indicates to the
on-board electronics whether or not the truck has the
electronic engine fan control feature.
ACFanActivation–This feature will allow fa n
activation through the ECM when r equested from the
ESC during AC operation.
Disable – Feature is turned off at all times.
Fan On Temperature – This parameter indicates the
coolant temperature that th e fan will be electronically
activated.
Fan Off Temp erature – This parameter indicates the
coolant temperature that th e fan will be electronically
deactivated.
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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