Circuit/System Testing
WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 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.
- Inspect for any condition that can reduce idle speed by increasing engine load.
- Incorrect torque converter clutch (TCC) operation
- Accessories that require additional torque to operate
- Excessive deposits in the throttle body
- Restricted exhaust
- Mechanical conditions that limit engine speed
Repair any conditions, if necessary.
- Inspect for the following conditions:
- Vacuum leaks
- A faulty positive crankcase ventilation (PCV) valve