1 ENGINE SYSTEMS 43
Electronic Control System
Electronic Control System Components
Figure 36 Electronic Control System
Operation and Function
The Electronic Control Module (ECM) monitors and
controls engine performance to ensure maximum
performance and adherence to emissions standards.
The ECM has four primary functions:
1. Provides Reference Voltage (V
REF
)
2. Conditions input signals
3. Processes and stores control strategies
4. Controls actuators
1. Voltage reference(V
REF
)
TheECMsuppliesa5voltV
REF
signal to input sensors
in the electronic control system. By comparing
the 5 volt V
REF
signal sent to the sensors with their
respective returned signals, the ECM determines
pressures, positions, and other variables important to
engine and vehicle functions.
The ECM supplies two independent circuits for V
REF
:
•V
REF
A supplies 5 volts to engine sensors
•V
REF
B supplies 5 vo lts to v ehicle senso rs
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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