GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The crankshaft position (CKP) system variation learn feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft and the crankshaft position sensor. The calculated error allows the engine control module (ECM) to accurately compensate for reference period variations. This enhances the ability of the ECM to detect misfire events over a wider range of engine speed and load.

The ECM stores the CKP system variation values after a learn procedure has been performed. If the actual CKP variation is not within the CKP system variation compensating valves stored in the ECM, DTC P0300 may set. If the CKP system variation values are not stored in the ECM memory, DTC P1336 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1336 Crankshaft Position (CKP) System Variation Not Learned

Conditions for Running the DTC

    • DTCs P0106, P0107, P0108, P0117, P0118, P0122, P0123, P0132, P0201, P0202, P0203, P0204, P0325, P0327, P0336, P0337, P0341, P0342, P0351, P0352, P0402, P0404, P0405, P0406, P0502, P0700, and P1404 are not set.
    • DTC P1336 runs continuously once the above conditions are met.

Conditions for Setting the DTC

    • The CKP system variation values are not stored in the ECM memory.
    • The manufacturer enable counter is set to zero.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

Conditions for Clearing the MIL/DTC

    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. The Crankshaft Position Variation Learn Procedure may have to be repeated up to 5 times before the procedure is learned.

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check - Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Perform the crankshaft position system variation learn procedure. Refer to Crankshaft Position System Variation Learn .

Does the scan tool display Learned This Ignition?

Go to Step 4

Go to Step 3

3

Inspect for the following conditions:

    • Worn crankshaft bearings
    • A damaged reluctor wheel
    • Debris between the CKP sensor and the reluctor wheel
    • Excessive crankshaft runout
    • A damaged Crankshaft
    • Interference in the signal circuit of the CKP sensor
    • A coolant temperature that is not within the Conditions For Running the DTC
    • The ignition switch is in the ON position until the battery has insufficient voltage
    • An ECM power disconnect with the ignition ON may erase the stored values and set DTC P1336

Did you complete the inspection?

Go to Step 4

--

4

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 5

5

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK