Circuit DescriptionThe crankshaft position and camshaft position sensors are Hall effect type sensors. The engine control module (ECM) provides a 5 volt supply to the position sensor and a return circuit. As the teeth on the crankshaft speed ring or the dimples in the back of the camshaft gear move past the position sensor, a signal is generated on the position sensor signal circuit. The ECM interprets this signal and converts it to an engine speed. A missing tooth on the crankshaft gear is used by the ECM to determine the position of the engine.

Component LocationThe crankshaft position and camshaft position sensor location varies, depending on engine model.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault CodesThe Engine Control Module (ECM) detected a loss of the crankshaft speed/position sensor while the engine was running.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.The backup engine speed sensor will be used by the ECM for the engine speed signal.Exhaust Gas Recirculation (EGR) valve operation will be disabled.Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.Conditions for Clearing the Fault CodeTo validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop TalkCauses of this fault include:

Open or short circuit of the +5-VDC supply, signal, or return wire in the engine harnessDamaged or malfunctioning engine speed sensorDamaged tone wheelSensor air gap that is too small or too large.

Possible Cause:1) Engine Wiring harness failure2) Sensor failure3) ECM calibration