480 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
IDM PWR Circuit Operation
Figure 473 IDM PWR circuit diagram
The IDM is grounded to the battery negative terminal
at IDM Pins X3-1, X3-2, X3-3, X3-22 and X3-26.
The IDM receives V
IGN
power at Pin X3-7. The power
signals the IDM to provide a ground path from Pin
X3-27to85toswitchtheIDMmainpowerrelay.
Switching the relay provides power from the battery
positive terminal through a fuse and relay contacts
30 and 87 to Pins X3-4, X3-23, X3-24 and X3-25.
Switching the relay also supplies power th ro ugh a
fuse to Pin X3–8 logic power. See truck Chassis
Electrical Circuit Diagram Manual for c ircu it numbers,
connector and fuse locations.
Fault Detection / Management
The IDM internally monitors battery voltage. When the
IDM continuously receives less than 7 V or more than
16 V a Diagnostic Trouble Code (DTC) will be set.
IDM PWR Diagnostic Trouble Codes (DTCs)
DTCs are read using the EST or by counting the
flashes from the amber and red ENGINE lamp.
DTC 525
IDM fault
• DTC 525 is set by the ECM when there is an
internal IDM failure. When DT C 525 is set,
replace the IDM.
• When DTC 525 is active the amber ENGINE lamp
is illuminated.
DTC 523
IDM V
IGN
voltage low
• DTC 523 is set by the ECM when the voltage from
V
IGN
is less than 7 V.
• DTC 523 can be set due to poor connections
between the IDM Pin X3-7 and the V
IGN
.
• DTC 523 will not illuminate the amber ENGINE
lamp
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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