P0339

DTC P0339 CKP Sensor Circuit Intermittent




Circuit Description
The Crankshaft Position (CKP) Sensor is mounted in the front of the engine behind the harmonic balancer. The CKP sensor works in conjunction with a 3X (4x on V8 applications) reluctor wheel mounted on the front of the crankshaft. The CKP sensor has a B+ power supply, a ground, and a signal circuit.

As the crankshaft rotates, the reluctor wheel teeth interrupt a magnetic field produced by a magnet located in the sensor. The sensor's internal circuitry detects this field and produces a square wave which the VCM monitors on the signal circuit. The VCM uses this signal to accurately measure crankshaft velocity which is important to ignition control spark timing, fuel injector timing and for misfire detection.

If a loss of the CKP signal or an erratic signal is detected by the VCM while the engine is running, this DTC will be set.

Conditions for Running the DTC
- The MAF is 5 g/s or greater.

Conditions for Setting the DTC
- The measured change in engine speed is greater than 1,000 RPM during a 125 ms time period, or
- The measured engine speed is 0 RPM and 4 or more camshaft position sensor pulses have occurred over a period of 2 to 3 seconds

Action Taken When the DTC Sets
The VCM illuminates the MIL after 2 consecutive driving cycles with the fault active.

Conditions for Clearing the MIL/DTC
- The VCM 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 startup 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 metallic particles. This could result in an intermittent DTC.

Check for the following:
- A chipped or damaged reluctor wheel
- An incorrect reluctor wheel
- The incorrect alignment of the CKP sensor to reluctor wheel
- Excessive crankshaft end play, Refer to Symptoms.

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.

If a repair is necessary, then refer to Wiring Repairs or Connector Repairs in Wiring Systems

Steps 1 - 4:

Steps 5 - 9:

Steps 10 - 14:

Steps 15 - 17:

Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. Checks the ignition feed circuit to the crankshaft position sensor
5. This step checks the duty cycle of the crankshaft position sensor