Cylinder Deactivation (Active Fuel Management) System Diagnosis
Cylinder Deactivation (Active Fuel Management) System Diagnosis
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides an overview of each diagnostic category.
Circuit Description
To provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the valve lifter oil manifold (VLOM) solenoids ON, to deactivate engine cylinders 1 and 7 on the left bank, and cylinders 4 and 6 on the right bank. The VLOM consists of 4 electrically operated normally closed solenoids, which directs pressurized engine oil to 8 deactivating valve lifters. All 4 VLOM solenoids are connected in parallel to a fused ignition circuit supplied by the powertrain relay. The control circuit for each solenoid is connected to an individual low side driver internal to the ECM. When enabling conditions for V4 mode are met, the ECM will command each low side driver to turn ON, in engine firing order sequence.
Diagnostic Aids
The VLOM solenoids are assigned to the following engine cylinders:
* Solenoid #1-Cylinder #1
* Solenoid #2-Cylinder #4
* Solenoid #3-Cylinder #6
* Solenoid #4-Cylinder #7
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Connector End Views By Name
Description and Operation
Cylinder Deactivation (Active Fuel Management) System Description Cylinder Deactivation (Active Fuel Management) System
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Programming and Relearning for scan tool information
Special Tools
EN-46999
For equivalent regional tools, refer to Special Tools Tools and Equipment
Circuit/System Verification
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 Oil Pressure Diagnosis and Testing. Inspect the Valve Lifter Oil Filter for a restriction or blockage. Refer to Valve Lifter Oil Filter Replacement Valve Lifter Oil Filter Replacement.
1. If sent here from DTC P0300-P0308 P0300 , continue with testing. If any other DTCs are set, then repair those DTC first. Refer to Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle.
2. 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 Symptoms - Engine Mechanical for further diagnosis.
3. Perform the Cylinder Deactivation (Active Fuel Management) System Compression Test Cylinder Deactivation (Active Fuel Management) System Compression Test. The Cylinder Deactivation System should pass the compression test.
4. 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.
Circuit/System Testing
1. Ignition OFF, remove the valve lifter oil manifold assembly ignition fuse from the underhood fuse block.
Note: Probe each terminal at the underhood fuse block with a test lamp connected to ground to determine what terminal to connect the DMM. The test lamp should not illuminate on the circuit that needs to be tested.
2. Connect a DMM between the ignition circuit fuse terminal going to the valve lifter oil manifold assembly and the ECM housing.
3. Ignition ON, command each Cylinder 1, 4, 6, and 7 Deactivation solenoid ON and OFF with the scan tool. Verify the resistance of each solenoid is between 11-18 ohm with the solenoid commanded ON.
• If greater than the specified range for all cylinder deactivation solenoids, test the ignition circuit for an open/high resistance.
• If greater than the specified range for one or more but not all cylinder deactivation solenoids, test both the control circuit and ignition circuit for an open/high resistance or an open/high resistance in the cylinder deactivation solenoid. If the circuits and solenoid test normal replace the engine control module.
4. If all circuits and components test normal, refer to Cylinder Deactivation (Active Fuel Management) Valve Lifter Oil Manifold Diagnosis and Testing Cylinder Deactivation (Active Fuel Management) Valve Lifter Oil Manifold Diagnosis and Testing for further mechanical diagnosis of valve lifter oil manifold assembly.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Valve Lifter Oil Manifold Replacement Valve Lifter Oil Manifold Replacement
* Control Module References Programming and Relearning for engine control module replacement, programming and setup.