P1335 GMC Code - Crankshaft Position Circuit

The Crankshaft Position (CKP) sensor sends pulses to the Powertrain Control Module (PCM) as the reluctor wheel teeth rotate past the CKP sensor. The PCM uses the CKP pulses to synchronize the ignition and fuel injector operation, and to time the interval between each CKP pulse. The PCM determines when an excessive change in crankshaft speed occurs by comparing each new time interval with the previous interval. A misfire causes an unexpected change in the crankshaft speed. A certain amount of acceleration/deceleration is expected between each firing stroke, but if the crankshaft speed changes more than an expected amount, the 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
The PCM learns variations during the Crankshaft Position System Variation Learning Procedure. The PCM compensates for these variations when performing detect misfire calculations. Only a scan tool can command the PCM to perform the Crankshaft Position System Variation Learning Procedure again.
Perform the learning procedure after the following actions:
- A PCM replacement
- Any operation or repair involving the crankshaft, the CKP sensor, or the CKP sensor to reluctor wheel gap relationship.
- An engine replacement.
- The ignition switch is in the ON position until the battery is drained.

• Faulty Crankshaft Position Sensor
• Crankshaft Position (CKP) Sensor harness is open or shorted
• Crankshaft Position (CKP) Sensor circuit poor electrical connection