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7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
IPR Circuit Operation
Figure 481 IPR circuit diagram
The IPR valve is supplied with voltage at Pin A of
the IPR connector through 12–pin connector (Pin 9)
from V
. The control of the injection control system
IGN
is gained by the ECM grounding Pin B of the IPR
valve through Pin X1-12 of the ECM. Precise control
is gained by varying the percentage of ON/OFF time
of the IPR solenoid. A high duty cycle indicates a
high amount of injection control pressure is being
commanded. A low duty cycle indicates less pressure
being commanded.
Fault Detection / Management
An open or short to ground in the ICP control circuit
can be detected by an on demand output circuit
check during KOEO Standard Test. If there is a circuit
fault detected a Diagnostic Trouble Code (DTC) will
be set. When the engine is running, the ECM can
detect if the injection control pressure is equal to
the desired pressure. When the measured injection
control pressure does not compare to the desired
pressure, the ECM will ignore the measured ICP
signal and controls the engine with the desired value.
IPR Diagnostic Trouble Codes (DTCs)
DTCs are read using the EST or by counting the
flashes from the amber and red ENGINE lamp.
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
DTC 241
IPR OCC self-test failed
•
DTC 241 is set by the ECM when the Output
Circuit Check (OCC) test has failed after the
KOEO Standard Test has been run.
•
DTC 241 can be set when a poor connection to
the IPR solenoid or inoperative IPR coil exists.
•
When DTC 241 is active the engine will not
run and the amber ENGINE lamp will not be
illuminated.
Tools
•
EST with MasterDiagnostics® software
•
EZ-Tech® interface cable
•
Digital Multimeter (DMM)
•
Breakout Box
•
Actuator Breakout Harness
•
Terminal Test Adapter Kit
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
495
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