GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Alero Export 🢒 Engine 🢒 Engine Controls - 3.4L 🢒 Crankshaft Position System Variation Learn

The crankshaft position system variation compensating values are stored in the PCM non-volatile memory after a learn procedure has been performed. If the actual crankshaft position system variation is not within the crankshaft position system variation compensating values stored in the PCM, DTC P0300 may set. Refer to Diagnostic Aid for DTC P0300.

The Crankshaft Position System Variation Learn Procedure should be performed if any of the following conditions are true:

    •  DTC P1336 is set.
    •  The PCM has been replaced.
    •  The engine has been replaced.
    •  The crankshaft has been replaced.
    •  The crankshaft harmonic balancer has been replaced.
    •  The crankshaft position sensor has been replaced.

Important :  The scan tool crankshaft position system variation learn function will be inhibited if engine coolant temperature is less than 70°C (158°F). Allow the engine to warm to at least 70°C (158°F) before attempting the crankshaft position system variation learn procedure.

The scan tool crankshaft position system variation learn function will be inhibited if any powertrain DTCs other than DTC P1336 are set before or during the crankshaft position system variation learn procedure. Diagnose and repair any DTCs if set.

The crankshaft position system variation learn function will be inhibited if the PCM detects a malfunction involving the camshaft position signal circuit, the 3X reference circuit, or the 24X reference circuit.

   •  If the scan tool indicates a problem with the Cam signal, refer to DTC P0341 Camshaft Position (CMP) Sensor Performance .
   •  If the scan tool indicates a problem with the 3X crank signal, refer to DTC P1374 Crankshaft Position (CKP) High to Low Resolution Frequency Correlation .
   •  If the scan tool indicates a problem with the 24X crank signal, refer to DTC P0336 Crankshaft Position (CKP) Sensor Circuit .

  1. Depress and hold the service brake pedal.
  2. Block the drive wheels.
  3. Ensure the hood is closed.
  4. Start the engine and allow engine coolant temperature to reach at least 70°C (158°F).
  5. Turn OFF the ignition switch.
  6. Select the crankshaft position variation learn procedure from the scan tool special functions list.
  7. Follow the instructions displayed on the scan tool. If the procedure is terminated, refer to Important above for instructions.
  8. Observe DTC status for DTC P1336.
  9. If the scan tool indicates that DTC P1336 ran and passed, the crankshaft position system variation learn procedure is complete. If the scan tool indicates DTC P1336 failed or not run, check for other DTCs. If no DTCs other than P1336 are set, repeat the crankshaft position system variation learn procedure as necessary.