528 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
VGT Pin-Point Diagnostics
Figure 500 VGT circuit diagram
NOTE: Turn the ignition switch to OFF before disconnecting engine wiring harness connectors from
components.
See truck Ch assis Electrical Circu it D iag ram Manual for circuit numbers, connector and fuse locations.
Actuator Control Voltage Check (Disc
onnect actuator harness from engine harness. Connect Turbo
Breakout Ha rn ess to e ng ine and actua
tor harness. Turn the ignition switch to ON.)
Test Point
Spec Comment
1to2 B+±0.5V
If < B+, continue with next test point, 1 to chassis gnd.
If equal to B+, check test point 3 to gnd (KOEO).
1tochassisgnd B+±0.5V
If equal to B+, but 1 to 2 did not eq
ual B+, check for
high resistance or open in grou
nd circuit. Do Harness
Resistance Checks – ECM to ECM
Chassis Ground
(page 537).
If < B+, disconnect the actuat
or harness from Turbo
Breakout Harness and rete
st.
• If < B+, do 12-pin Actuator P
ower Voltage Check
(page 532).
• If equal to B+, the concern
is either high resistance
in wiring or the VGT actuat
or. Do Harness
Resistance Checks (pag
e 537) to confirm integrity
of wiring. See truck Ch
assis Electrical Circuit
Diagram Manual.
If integrity of wiring
is confirmed to be in good
condition, replace V
GT actuator.
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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