Circuit/System Verification

WARNING: This page is about a different car, the 2010 GMC Sierra and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description .
Ignition ON, verify the scan tool hood position parameter displays Open.
- If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.
Verify that no other DTCs are set.
- If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
Engine idling, verify there is no abnormal engine noise.
- If there is an abnormal engine noise, refer to Symptoms - Engine Mechanical .
Observe the Misfire Current Counters with a scan tool. The Misfire Current Counters should not be incrementing. Random misfires that are not steadily incrementing may be normal.
Operate the vehicle within the Conditions for Running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.