The ECM uses the CKP and CMP signal to calculate engine speed and position. The CMP sensor provides the ECM with a signal that indicates camshaft position.
The CMP contains a permanent magnet which creates a magnetic field. The signal is created when the camshaft peg rotates past the sensor breaking the magnetic field. The ECM pins for the CMP sensor are CMP positive X1-9 and CMP negative X1-10.
NOTE: Engine will not operate without CMP signal.
Fault Detection / Management
An inactive CMP signal during cranking is detectable by the ECM. During engine cranking the ECM monitors the CKP signal and Injection Control Pressure (ICP) to verify the engine is rotating. If the CMP signal is inactive during this time a DTC will be set. Electrical noise can also be detected by the ECM. When the level is sufficient to effect
engine operation a corresponding DTC will be set. An inactive CMP signal will cause a no start condition.
CMP Diagnostic Trouble Codes (DTCs)
DTCs are read using the EST or by counting the flashes from the amber and red ENGINE lamp.
DTC 143
Incorrect CMP signal signature
• DTC 143 is set by the ECM when the CMP transition occurs at the wrong CKP location.
• DTC 143 can be set due to a mistimed camshaft to crankshaft, electrical noise in the CMP circuit, or a failed CMP sensor.
DTC 145
CMP signal inactive
• DTC 145 is set by the ECM when CMP signal is not detected while CKP signal is active or ICP has increased.
• DTC 145 can be set due to an open, short to ground or open voltage source in the CMP circuit. A failed CMP sensor can cause DTC 145 to be set.
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
• Digital Multimeter (DMM)
• Breakout Box
