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.
- Ignition ON, observe the DTC information with a scan tool. Verify that no HO2S heater DTCs are set.
- If any HO2S heater DTCs are set, perform those diagnostics first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Engine idling, move the appropriate HO2S 2 harness connector and the engine control module (ECM) harness connector while monitoring the HO2S 2 voltage parameter with a scan tool. Verify that the HO2S parameter does not change abruptly while moving the related harnesses.
- If the HO2S parameter does change abruptly while moving the related harnesses repair the circuit as necessary.
- Engine idling at operating temperature, observe the appropriate HO2S 2 parameter with a scan tool. The HO2S 2 value should change greater than 200 mV when the throttle is quickly cycled 3 times from closed to wide open and back to closed after running the engine at 1,500 RPM for 30 seconds.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.