Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

To provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the displacement on demand (DoD) system ON to deactivate engine cylinders 1 and 7 on the left bank, and cylinders 4 and 6 on the right bank, switching to V4 mode. The DoD system consists of an electro-hydraulic actuator device called the VLOM assembly. All 4 VLOM solenoids are connected in parallel to a fused ignition 1 voltage circuit supplied by the powertrain relay. The ground or control circuit for each solenoid is connected to an individual low side driver internal to the ECM. When all enabling conditions for V4 mode are met, the ECM will command the low side driver to turn ON, grounding each VLOM solenoid control circuit in engine firing order sequence.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

Mechanical Information Reference

Displacement on Demand (DoD) System Diagnosis

Scan Tool Reference

Special Tools Required

1. If DTC P1101 is set, refer to Displacement on Demand (DoD) System Diagnosis .
2. With the ignition ON and the engine OFF, command each VLOM solenoid ON and OFF several times using the scan tool Output Control function. You should be able to hear the solenoid energize and de-energized with each scan tool output control command.

1. Connect a vacuum gage to the evaporative emission (EVAP) vacuum tube fitting on the intake manifold. Do not use a compound pressure and vacuum gage. The vacuum gage on a hand held vacuum pump or Mityvac will work fine for this test.
2. Allow the engine to reach normal operating temperature.
3. With a scan tool, command each DoD solenoid ON, one at a time. Each time a DoD solenoid is commanded ON, you should observe a fluctuating drop of 0.5-2 inches of Hg or vacuum on the gage. The drop in vacuum occurs because both the intake and exhaust valves are deactivated for that cylinder. Also, the engine will have a misfire when that cylinder is deactivated. For additional DoD mechanical testing, refer to Displacement on Demand (DoD) System Diagnosis .
4. Clear any DTCs with a scan tool.
5. With a scan tool, monitor the following parameters in the Cylinder Deactivation Data menu:

•	The Cylinder Deactivation System command

•	The Cylinder #1, 4, 6, and 7 Deactivation Solenoid command

•	The Cylinder Deactivation Performance test

6. Road test the vehicle at 40 mph, under a light load condition with a steady throttle input that will allow V4 mode. The scan tool should display V4 mode for the Cylinder Deactivation System command, ON for each Cylinder Deactivation Solenoid command, and OK for the Cylinder Deactivation Performance test.

⇒	If the engine does not switch to V4 mode, then review the DoD inhibit fault listing at the end of the Cylinder Deactivation Data menu, or refer to Displacement on Demand (DoD) System Description for inhibit reasons.

⇒	If the engine does switch to V4 mode, review the DoD driving information in the Features and Controls section of the owner’s manual with the vehicle operator, or instruct the vehicle operator in the proper driving techniques to obtain V4 mode.

1. With the ignition OFF, disconnect the VLOM wire harness electrical connector. Connect the cable that is labeled POWER from the DoD tester to the electrical connector on the VLOM assembly. Connect both the positive and the negative power leads of the DoD tester to the respective battery terminals at the battery. Command each VLOM solenoid ON and OFF several times using the DoD tester. You should be able to hear the solenoids being energized and de-energized with each ON and OFF command.

⇒	If you cannot hear each solenoid being energized, replace the VLOM assembly.

2. Disconnect the cable that is labeled POWER from the VLOM assembly. Connect the cable that is labeled RESISTANCE to the VLOM assembly. Connect the test leads from a DMM to the resistance test ports on the DoD tester. Set the DMM to measure resistance and zero out the DMM display. Press and hold each solenoid switch pad for solenoids #1 through #4, one at a time, on the DoD tester. Monitor the DMM display.

⇒	If each solenoid does not measure within 11-18 ohms of resistance, replace the VLOM assembly.

3. Remove one DMM test lead from the DoD tester. Connect the DMM test lead to a good ground on the engine. Press and hold each solenoid switch pad for solenoids #1 through #4, one at a time, on the DoD tester. Monitor the DMM display.

⇒	If continuity or resistance is detected for any VLOM solenoid, replace the VLOM assembly.

1. Install any components or connectors that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.
3. Clear the DTCs.
4. Turn OFF the ignition for 60 seconds.

⇒	If the repair was related to a DTC, duplicate the condition for running the DTC and use the Freeze Frame/Failure Records, if applicable, in order to verify the DTC does not reset.

⇒	If the DTC resets or another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.

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OR

⇒	If the repair was symptom related, duplicate the conditions under which the customer concern occurred to verify the repair. If the customer concerns reoccurs, return to Symptoms - Vehicle and perform the appropriate symptom diagnostic.