Impala V6-3.9L (2007)
Valve Deactivation Solenoid: Testing and Inspection
Cylinder Deactivation (Active Fuel Management) System Diagnosis
Diagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Testing and Inspection/Initial Inspection and Diagnostic
Overview/Diagnostic Starting Point - Vehicle
Circuit/System 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, 3, and 5. The VLOM consists of 3 electrically operated normally closed solenoids, which
directs pressurized engine oil to 6 deactivating valve lifters. All 3 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
V3 mode are met, the ECM will command the low side driver to turn ON, in engine firing order sequence
Diagnostic Aids
The valve lifter oil manifold (VLOM) solenoids are assigned to the following engine cylinders:
*
Solenoid #1 = Cylinder #1
*
Solenoid #2 = Cylinder #3
*
Solenoid #3 = Cylinder #5
Important: This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery
Inspection/Test. See: Starting and Charging/Testing and Inspection/Component Tests and General Diagnostics/Battery Inspection/Test
1. Ignition ON, engine OFF, measure and record the ignition voltage at the fuse for the VLOM assembly.
2. Remove the fuse for the VLOM assembly from the underhood fuse block.
3. Connect a DMM in series with a 15A fused jumper wire and a non-fused jumper wire across the exposed fuse terminals in the underhood fuse
block.
4. Select the 10 A range and zero out the DMM display.
5. Command each VLOM solenoid ON, with a scan tool.
6. Record the amperage reading display on the DMM for each solenoid.
7. Calculate the resistance for each solenoid circuit; divide the previously recorded voltage by the amperage for each VLOM solenoid circuit. The
total resistance for each solenoid circuit should be within 11-22 ohms.
^
If the total circuit resistance exceeds 22 ohms, then an open/high resistance condition exists in the VLOM solenoid circuit.
Circuit/System Verification
1. If any DTCs are set, then repair those DTCs first. Go to Diagnostic System Check - Vehicle. See: Testing and Inspection/Initial Inspection and
Diagnostic Overview/Diagnostic Starting Point - Vehicle
2. Start and idle the engine.
3. Allow the engine to reach normal engine operating temperature. The engine should idle smoothly, without any misfires. If the engine misfires,
refer to DTC P0300. See: Testing and Inspection/Diagnostic Trouble Code Tests and Associated Procedures/P Code Charts/P0300
4. Monitor the cylinder deactivation system data parameters with a scan tool.
5. Road test the vehicle under light throttle and load conditions that will allow the engine control module (ECM) to command V3 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 with V3 mode operation.
^
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 V3
mode.
^
If the vehicle does not pass the Circuit/System Verification, then review the cylinder deactivation inhibit reasons listed on the scan tool.
Circuit/System Testing
Electrical System Testing
Ignition ON, engine OFF, command each valve lifter oil manifold (VLOM) solenoid ON, and OFF, using the scan tool. Standing next to the engine
compartment, you should be able to hear the solenoids energize, and de-energize with each command.
If you cannot here each solenoid energize and de-energize, then refer to DTC P3401, P3417, or P3433. See: Testing and Inspection/Diagnostic Trouble
