International VT 365 Service Manual page 31

ICP Closed Loop System
Figure 22 ICP closed loop system
The ICP is a closed loop system that uses the ICP
sensor to provide feedback to the ECM. The ECM
uses the ICP sensor to continuously monitor ICP
and adjust the duty cycle to the IPR to match engine
requirements.
ICP control
Figure 23 ICP control
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
ENGINE SYSTEMS
ICP system operation
The solenoid receives a pulse width modulated signal
from the ECM that indicates the on/off time the control
valve is energized. The pulse is modulated to control
ICP pressure in the range of 3 to 20 MPa (500 to 3,000
psi).
The IPR valve is mounted in the high-pressure
pump cover. The IPR valve maintains the desired
ICP by dumping excess oil out the bottom of the
high-pressure pump cover.
High-pressure oil is routed to the IPR valve and ICP
sensor through the discharge tube and passages in
the high-pressure pump cover.
As the demand for ICP increases, the ECM increases
the pulse width to the IPR solenoid.
demand decreases, the ECM decreases the (duty
cycle) to the solenoid, allowing oil to flow from the
drain orifice.
The ECM sets Diagnostic Trouble Codes (DTCs), if
the ICP electrical signal is out of range. DTCs are
also set if an ICP signal corresponds to an out of
range value for injection control pressure for a given
operating condition.
The ECM will ignore ICP signals that are out of range.
The IPR valve will operate from preprogrammed
default values. This is called an Open Loop Operation.
EGES295-2
Follow all warnings, cautions, and notes.
© 2006 International Truck and Engine Corporation
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When ICP