P0337

Schematic:

The crankshaft position (CKP) sensor produces an AC voltage of different amplitude and frequency depending on the velocity of the crankshaft. The CKP sensor works in conjunction with a 58 tooth reluctor wheel on the crankshaft. Each tooth is spaced six degrees apart with one span having a 12 degree space that is uncut. This uncut portion creates a pattern that enables the ECM to determine top dead center for cylinder # 1 and its mating cylinder, cylinder # 4. The camshaft position (CMP) sensor is then used to determine when cylinder # 1 is on its compression stroke. With both CKP sensor and CMP sensor inputs, the ECM can properly synchronize ignition timing, fuel delivery and spark knock control. The ECM uses a pull-up voltage of 2.5 volts on each CKP sensor wire used for the reduction of noise interference from electromagnetic generating devices. DTC P0337 will set if the ECM detects less CKP sensor signal pulses within a certain number of crankshaft revolutions when the engine is cranking or running. This indicates that the CKP sensor pulse frequency is lower than expected, which is most likely due to missing, broken or damaged crankshaft reluctor teeth or electromagnetic interference.

DTC PARAMETERS
DTC P0337 will set if the ECM detects less pulses per crankshaft revolution then expected (less than 58 pulses) from the CKP sensor A/C voltage signal when:
^ Condition exists for eight consecutive crankshaft revolutions in which the same number of missing pulses (+/-1 pulse) are being detected each crankshaft revolution
^ A valid CMP sensor signal is being received
^ Engine is cranking or running

DTC P0337 diagnostic runs continuously with engine running or cranking.

P0337 is a type B DTC.

DIAGNOSTIC AIDS

NOTE: A short to ground on either circuit 5024 or 5039 will not affect the CKP sensor signal to the ECM and will NOT set any CKP sensor circuit DTCs.

Make sure the battery cables are clear of the CKP sensor wiring, which may cause electromagnetic interference. Make sure that 2.5 volts are present on circuit 5024 and 5039 from the ECM with the CKP sensor disconnected. This voltage protects against EM interference.

Missing, damaged or broken teeth on the crankshaft reluctor wheel can set this DTC. If the crankshaft was recently replaced or the vehicle/engine is new and this DTC is set, check all teeth on crankshaft reluctor wheel.

If the above checks out OK, replace the CKP sensor.