GM Service Manual Online
For 1990-2009 cars
Makes 🢒 Chevrolet 🢒 2004 🢒 C-Series Medium Duty Truck C6/7/8 - Mexico 🢒 Engine 🢒 Engine Controls - 8.1L 🢒 Crankshaft Position System Variation Learn

    Important: For additional diagnostic information, refer to DTC P1336 .

  1. Install a scan tool.
  2. With a scan tool, monitor the powertrain control module for DTCs. If other DTCs are set, except DTC P1336, refer to Diagnostic Trouble Code (DTC) List for the applicable DTC that set.
  3. With a scan tool, select the crankshaft position variation learn procedure.
  4. Observe the fuel cut-off for the engine that you are performing the learn procedure on.
  5. The scan tool instructs you to perform the following items:
    6. • Block the drive wheels.
    • Apply the vehicles parking brake.
    • Cycle the ignition from OFF to ON.
    • Apply and hold the brake pedal.
    • Start and idle the engine.
    • Place the vehicles transmission in Park (A/T) or Neutral (M/T).
    • The scan tool monitors certain component signals to determine if all the conditions are met to continue with the procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components:
       - Crankshaft position (CKP) sensors activity--If there is a CKP sensor condition, refer to the applicable DTC that set.
       - Camshaft position (CMP) sensor activity--If there is a CMP sensor condition, refer to the applicable DTC that set.
       - Engine coolant temperature (ECT)--If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.
  6. With the scan tool, enable the crankshaft position system variation learn procedure.

    7. Important: While the learn procedure is in progress, release the throttle immediately when the engine starts to decelerate. The engine control is returned to the operator and the engine responds to throttle position after the learn procedure is complete.

  7. Slowly increase the engine speed to the RPM that you observed.
  8. Immediately release the throttle when fuel cut-off is reached.
  9. The scan tool displays Learn Status: Learned this ignition. If the scan tool does NOT display this message and no additional DTCs set, refer to Symptoms - Engine Mechanical in Engine Mechanical - 8.1L. If a DTC set, refer to Diagnostic Trouble Code (DTC) List for the applicable DTC that set.
  10. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.