352 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
CKP Circuit O peration
Figure 407 CKP circuit diagram
The ECM uses the CKP and CMP signal to calculate
engine speed and position. The CKP sensor provides
the ECM with a signal that indicates crankshaft speed
and position. The CKP contains a permanent magnet
that creates a magnetic field. The signal is created
when the timing disk rotates and breaks the magnetic
field created by the sensor. The ECM pins for the CKP
sensor are CKP negative X1-2 and CKP positive X1-1.
NOTE: Engine will not operate without CKP signal.
Fault / Detection Management
An inactive CKP signal during cranking is detectable
by the ECM. During engine cranking the ECM
monitors the CMP signal a nd Injection C ontrol
Pressure (ICP) to verify the engine is rotating. If the
CKP signal is ina c tiv e during this time a DTC will
be set. Electrical noise can also be detecte d by the
ECM, if the level is sufficient to effect engine operation
a corresponding DTC will be set. An inactive CKP
signal will cause a no start condition.
CKP Diagnostic Trouble Codes (DTCs)
DTCs are read using the EST or by counting the
flashes from the amber and red ENGINE lamp.
DTC 146
CKP signal inactive
• DTC 146 is set by the ECM when CKP signal is
not detected while the CMP signal is active or ICP
has increased.
• DTC 146 can be set due to an open short to
ground or voltage source in the CKP circuit. A
failed CKP sensor can also set DTC 146.
DTC 147
Incorrect CKP signal signature
• DTC 147 is set by the ECM when the CKP
signal has too few or many transitions per engine
rotation .
• DTC 147 can be set due to an electrical noise in
the CKP circuit or a failed CKP sensor.
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
• Digital Multimeter (DMM)
• Breakout Box
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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