382 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
ECM PWR Circuit Operation
Figure 425 ECM PWR circuit diagram
The ECM is grounded to the battery negative terminal
at ECM Pin X3-6 and X 3-7.
The ECM receives V
IGN
power at Pin X3-3. The power
signals the ECM to provide a ground path from Pin
X3-5 to 85 to switch the ECM main power relay.
Switching the relay provides power from the battery
positive terminal through 2 fuses and relay contacts
30 and 87 to Pins X4-1 and X4-2. See truck Chassis
Electrical Circuit Diagram Manual for c ircu it numbers,
connector and fuse locations.
Fault Detection / Management
The ECM internally monitors battery voltage. When
the ECM continuously receives less than 7 V or more
than 23 V, a D iagnostic Trouble Code (DTC) will be
set.
ECM PWR Diagnostic Trouble Codes (DTCs)
DTCs are read using the EST or by counting the
flashes from the amber and red ENGINE lamp.
DTC 112
Electrical system voltage B+ out of range high
• DTC 112 is set when the ECM detects an
alternator output greater than 23 V at Pin X3–3
for more than 0.5 second.
• DTC 112 can be set when jump starting the
engine and additional voltage is introduced.
Incorrect external battery connections can ca use
the voltage increase.
• If the condition causing DTC 112 is intermittent,
the code will change from active to inactive status.
DTC 112 will not illumina te 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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