Circuit/System Verification
WARNING: This page is about a different car, the 2012 GMC Yukon, 2012 Chevrolet Tahoe, and 2012 Cadillac Escalade. 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 and fuel cap removed, verify that the FTP sensor parameter is between 1.3-1.7 V.
- If not within the specified range, go to the FTP sensor section in Circuit/System Testing.
- Install the fuel cap.
- With the engine running, the EVAP vent solenoid valve open, use a scan tool to command the EVAP purge solenoid valve to 100 %. The fuel tank vacuum should not increase to more than -15 mm Hg (-8 in H2O).
- If greater than the specified range, go to the restriction section in Circuit/System Testing.
- Using the scan tool, decrease the canister purge duty cycle from 100 % to 0 %. The vacuum should decrease to near zero.
- If the fuel tank vacuum does not return to zero or appears to decrease too slowly go to the restriction section in Circuit/System Testing.
- 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 data.