Circuit/System Verification
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
- If sent here from DTC P0300-P0308 , , continue with testing. If any other DTCs are set, then repair those DTC first. Refer to Diagnostic System Check - Vehicle (without HP2) .
- Engine idling at the normal operating temperature. Verify there is no abnormal engine noise.
- If there is an abnormal engine noise, refer to Symptoms - Engine Mechanical for further diagnosis.
- Perform the Cylinder Deactivation (Active Fuel Management) System Compression Test . The Cylinder Deactivation System should pass the compression test.
- Road test the vehicle under light throttle and load conditions that will allow the ECM to command V4 mode. If all enabling conditions are met for cylinder deactivation, and if no internal engine hydraulic/mechanical fault conditions are present, the ECM will continue operation in V4 mode.
- If the vehicle passes the Circuit/System Verification test, then review the active fuel management driving information in the Features and Controls section of the owners manual with the vehicle operator, or instruct the vehicle operator in the proper driving techniques to obtain V4 mode.
- If the vehicle does not pass the Circuit/System Verification test, then review the cylinder deactivation inhibit reasons listed on the scan tool.
NOTE:
The engine oil level and the oil pressure are critical to the correct operation of the Cylinder Deactivation System. Verify that the engine has the correct oil level and the correct oil pressure before continuing with this diagnostic. Refer to Oil Pressure Diagnosis and Testing . Inspect the Valve Lifter Oil Filter for a restriction or blockage. Refer to Valve Lifter Oil Filter Replacement .