Circuit/System Verification

WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 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, observe the scan tool DTC information. DTC P0641 or P0651 should not be set.
- If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P0641 or P0651 for further diagnosis.
Verify restrictions do not exist in the exhaust system. Refer to Restricted Exhaust .
Engine idling, observe the scan tool MAF Sensor parameter. The reading should be between 2, 000-3, 900 Hz depending on the ECT.
A wide open throttle (WOT) acceleration from a stop should cause the MAF Sensor parameter on the scan tool to increase rapidly. This increase should be from 4-9 g/s at idle to greater than 180 g/s at the time of the 1-2 shift.
Use the scan tool and compare the MAF Sensor parameter to a known good vehicle under various operating conditions.
Ignition ON, observe the MAP sensor pressure parameter and compare to the Altitude Versus Barometric Pressure table. The MAP sensor reading should be within the specified range.
- If the MAP sensor pressure is not within the specified range, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P0106 for further diagnosis.
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.