DTC P1336: CKP System Variation Not Learned: Description

Crankshaft Position (CKP) sensor sends pulses to Powertrain Control Module (PCM) as reluctor wheel teeth rotate past CKP sensor. PCM uses CKP pulses to synchronize ignition and fuel injector operation, and to time 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. Interval between CKP sensor pulses is extremely small. At high engine speeds, slight variations in crankshaft, reluctor wheel, and CKP sensor make misfire detection difficult: PCM learns variations during crankshaft position system variation learning procedure. PCM compensates for these variations when performing misfire calculations. Only a scan tool can command PCM to perform crankshaft position system variation learning procedure again. Perform learning procedure after the following actions:

• A PCM replacement
• Any operation or repair involving crankshaft, CKP sensor, or CKP sensor to reluctor wheel gap relationship.
• An engine replacement.
• Ignition switch is in the ON position until the battery is drained.

Disconnecting PCM will not erase the learned crankshaft position system variation as long as ignition is off. Reprogramming PCM does not require running crankshaft position system variation learn procedure unless PCM is new. DTC P1336 sets if crankshaft position system variation is not within an acceptable range, or cannot be learned.