Fan Clutch Pin-Point Diagnostics - Navistar International DT 466 Diagnostic/Troubleshooting Manual

400 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS

Fan Clutch Pin-Point Diagnostics

Figure 435 Fan clutch circuit diagram
Voltage Checks at Fan Connector (Disconnect fan connector. Turn the ignition switch to ON.)
Test Point
KOEO
A to gnd
B to gnd
Output State Test - Voltage Check at Fan Connector (Disconnect fan connector. 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
Output State Test - Low
A to gnd
Output State Test - High
A to gnd
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Spec
B+ ± 0.5 V
0 V to 0.25 V
Spec
0 V to 0.25 V
B+ ± 0.5 V
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
Comment
If < B+, check relay. Also check for an open circuit,
short to ground, or short to voltage source. Do Output
State Test - Voltage Check at Fan Connector.
If > 0.25 V, check for an open ground circuit or a short to
voltage source. Do Harness Resistance Checks.
Comment
If > 0.25 V, check relay. Also check for short to voltage
source.
If < B+, check relay. Also check for an open circuit,
short to ground, or a short to voltage source. Do Output
State Test - Voltage Checks at Fan Relay.