P0337

Circuit Description
The Crankshaft Position (CKP) Sensor is a sensor designed to detect changes in a magnetic field. The Control Module (PCM/VCM) supplies the CKP sensor a signal and ground circuits. Ignition voltage is supplied to the sensor by an independent circuit. The CKP sensor produces a magnetic field whenever the ignition is ON. The CKP sensor is mounted near a reluctor wheel that is attached to the crankshaft. When the crankshaft rotates (the engine is cranking or running) the toothed reluctor wheel changes the magnetic field. The CKP sensor converts each change in the magnetic field into a "pulse". The number of teeth on the reluctor wheel determines how many pulses the CKP sensor detects per crankshaft rotation. The CKP sensor signal is used to determine engine speed, crankshaft position, and detect misfire.
If the frequency of the CKP is less than expected by the VCM, this DTC will be set.

Conditions for Running the DTC
^ The engine speed is less than 4,000 RPM
^ The MAF is 5 g/s or greater

Conditions for Setting the DTC
The crankshaft position sensor duty cycle is less than a calibrated percent

Action Taken When the DTC Sets
^ The Control Module illuminates the Malfunction Indicator Lamp (MIL) if a failure is detected during 2 consecutive key cycles.
^ The Control Module will set the DTC and records the operating conditions at the time the diagnostic fails. The Control Module stores the failure information in the scan tools Freeze Frame and/or the Failure Records.

Conditions for Clearing the MIL/DTC
^ The Control Module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the Engine Coolant Temperature is more than 70°C (158°F) during the same ignition cycle).
^ Use the scan tool Clear Information function.

Diagnostic Aids
Inspect the face of the CKP sensor for metal shavings. Also check for the following conditions:
^ A chipped or damaged reluctor wheel
^ An incorrect reluctor wheel
^ Incorrect alignment of the CKP sensor to the reluctor wheel
^ Excessive crankshaft end play

Check for Electro-magnetic Interference.
Refer to Symptoms. Symptom Related Diagnostic Procedures

An intermittent may be caused by any of the following conditions:
^ A poor connection
^ Rubbed through wire insulation
^ A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. All three circuits must be jumped so that the engine will run. This test checks the duty cycle output of the crankshaft position (CKP) sensor. An engine will start with a low duty cycle failure but will not run very well.