Begin the system diagnosis by reviewing the Disassembled Views , Engine Component Description , Lubrication Description - Main Pressure Below 55 psi with Cylinder Deactivation (Active Fuel Management) Off , Lubrication Description - Main Pressure Above 55 psi with Cylinder Deactivation (Active Fuel Management) Off , Lubrication Description - Main Pressure Below 55 psi with Cylinder Deactivation (Active Fuel Management) On Lubrication Description - Main Pressure Above 55 psi with Cylinder Deactivation (Active Fuel Management) On and Cylinder Deactivation (Active Fuel Management) System Description . Reviewing the description and operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the description and operation information will also help you determine if the condition described by the customer is normal operation. Refer to Symptoms - Engine Mechanical in order to identify the correct procedure for diagnosing the system and where the procedure is located.