404 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
Fan Air Solenoid Pin-Point Diagnostics
Voltage Checks a t Fan Solenoid Connector (Disconnect solenoid. Turn the ignition switch to ON.)
Test Point
Spec Comment
KOEO
Atognd B+±0.5V
If < B+, check for open circuit. Do Harness Resistance
Checks.
B to gnd 0 V to 0.25 V
If > 0.25 V, check ECM programming or open circuit.
Output State Test - Voltage Check at Fan Solenoid Connector (Disconnect solenoid. Turn the ignition
switch to ON. Run the Output State Tests. For help, see “Diagnostic Software Operation” in Section 3 (page
68) for procedure to run the Low and High Output State Tests.)
Test State/Point Spec Comment
Output State Test - Low
B+ to Pin B B+ ± 0.5 V
If < B+, check ECM programming and check for open
circuit.
Output State Test - High
B+ to Pin B 0 V to 0.25 V
If > 0.25 V, check ECM programming and check f
or
short to voltage source.
Output State Test - Voltage Checks at ECM (Disconnect X3 and X4 from ECM. Connect breakout box
X3 and X4 to ECM and wiring harness. Turn the ignition switch to ON. Run the Output State Tests. For
help, see “Diagnostic Software Operation” in Section 3 (page 68) for procedure to run the Low and High
Output State Tests.)
Output State Test - Low
X3–3 to X4–14 B+ ± 0.5 V
If < B+, verify that ECM is progr
ammed correctly. If
ECM is programmed correctly,
replace ECM.
Output State Test - High
X3–3 to X4–14 0 V to 0.25 V
If > 0.25 V, verify that ECM is programmed correctly.
If ECM is programmed correctly, replace ECM.
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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