7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS 529
2tochassisgnd 0Vto0.25V
If > 0.25 V disconnect the actuator harness and retest.
• If > 0.25 V, do 12-pin Actuator Power Voltage Check
(page 532).
• If < 0.25 V, the concern is either high resistance in
wiring or the VGT actuator. Do Harness Resistance
Checks (page 537) to confirm inte grity of wiring.
See truck Chassis Electrical Circuit Diagram
Manual.
If integrity of w iring is confirmed to be in good
condition, replace VGT actuator.
3 to gnd (KOEO) DMM set to V - DC
1
DMM s et to Duty Cycle
2
Iftestpoint1to2istospecific ation an d no volt age or
duty cycle is m easured, disconnect actuator harness.
Connect 500 Ohm Resistor Harness between Pin 3 and
Pin 2. Retest by measuring across Pin 3 and Pin 2.
• If after retesting and values are not to specifications,
do Actuator Control Voltage Check at ECM (page
534).
• If values are to specifications, the concern is either
high resistance in the wiring or the VGT actuator.
Do Harness Resistance C hecks (page 537) to
confirm integrity of wiring .
If integrity of w iring is confirmed to be in good
condition, replace VGT actuator.
1
Values are c alibration depende nt. See “DT 466 Performance Speci fi cations” – Appendix A (page 595) or “DT 570 and
HT 570 P erforman ce Specifications – Appe
ndix B ( page 619).
2
Use the EST with MasterDiagnostics® software to view VGT duty cycle with key-on engine-off. When using the Fluke
88 DMM, measurement is typically within 2% of what MasterDiagnostics® reads.
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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