DTC P1336: Crankshaft Position Sensor Variation Not Learned: Description

Crankshaft Position (CKP) sensor sends pulses to Powertrain Control Module (PCM) when reluctor wheel teeth rotate past CKP sensor. PCM uses CKP pulses to synchronize ignition and fuel injector operation, and to time the interval between each CKP pulse. PCM determines when an excessive change in crankshaft speed occurs by comparing each new time interval with previous interval. A misfire causes an unexpected change in crankshaft speed. A certain amount of acceleration or deceleration is expected between each firing stroke, but if crankshaft speed changes more than an expected amount, PCM interprets this as a misfire. The interval between CKP sensor pulses is extremely small. At high engine speeds, slight variations in the following components make misfire detection difficult:

• Crankshaft
• Reluctor Wheel
• CKP Sensor

PCM learns variations during crankshaft position sensor variation learn procedure. PCM compensates for these variations when performing detect misfire calculations. Only a scan tool can command PCM to perform CKP variation learn procedure again. See CRANKSHAFT POSITION SENSOR VARIATION LEARN PROCEDURE  under PROGRAMMING. Perform learn procedure after the following actions:

• PCM replacement.
• Any operation or repair involving crankshaft, CKP sensor or CKP sensor-to-reluctor wheel gap relationship.
• Engine replacement.
• Ignition switch left in ON position until battery is drained.

Reprogramming PCM does not require running the CKP variation learn procedure unless PCM is new or from another vehicle.