DTC Descriptor

DTC P3401: Cylinder 1 Deactivation Solenoid Control Circuit

DTC P3425: Cylinder 4 Deactivation Solenoid Control Circuit

DTC P3441: Cylinder 6 Deactivation Solenoid Control Circuit

DTC P3449: Cylinder 7 Deactivation Solenoid Control Circuit

Diagnostic Fault Information

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

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition 1 Voltage Circuit to Deactivation Solenoids	P3401, P3425, P3441, P3449	P3401, P3425, P3441, P3449	P3401, P3425, P3441, P3449	--
Deactivation Solenoid Control Circuits	P3401, P3425, P3441, P3449	P3401, P3425, P3441, P3449	P3401, P3425, P3441, P3449	--

Typical Scan Tool Data

Cylinder Deactivation Data

Circuit	Normal Range	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running, vehicle traveling at 40 mph, under a light load condition, and steady throttle input
Cylinder Deactivation System Command	V4 or V8 mode	V8 mode	V8 mode	V8 mode
Cylinder 1, 4, 6, 7, Deactivation Solenoid Command	ON or OFF	OFF	OFF	OFF
Cylinder 1, 4, 6, 7, Deactivation Solenoid Circuit Status	Incomplete or OK	Short to GRD/Open	Short to GRD/Open	Short to B+
Cylinder Deactivation Performance	OK	Fault	Fault	Fault

Circuit/System Description

Each of the four valve lifter oil manifold (VLOM) solenoid windings are connected in parallel to a fused ignition 1 voltage circuit, supplied by the powertrain relay, in the underhood fuse block. The ground or control circuit for each solenoid is connected to an individual low side driver, internal to the engine control module (ECM). Each low side driver has its own fault detection circuit, which monitors the solenoid control circuit for an incorrect voltage level. If an incorrect voltage level, such as an open, high resistance, short to ground, or a short to voltage is detected, the low side driver will turn OFF and the fault detection circuit will communicate the condition to the central processor internal to the ECM. This DTC will set when the ECM detects an incorrect voltage level on the ignition 1 voltage circuit to the solenoids, or a solenoid control circuit, after the ignition switch is turned ON. This DTC could also set if an incorrect voltage level is detected when the ignition switch is turned OFF, before the ECM powers down.

Conditions for Running the DTC

Conditions for Setting the DTC

Action Taken When the DTC Sets

Conditions for Clearing the DTC

Diagnostic Aids

Reference Information

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

Circuit/System Verification

Electrical Verification

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-energize with each scan tool output control command.

Mechanical Verification

1. Connect a vacuum gage to the EVAP vacuum tube fitting on the electronic throttle body. Do not use a compound pressure and vacuum gauge. 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 Displacement on Demand (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 de-activated for that cylinder. Also the engine will have a misfire when that cylinder is de-activated. For additional DoD mechanical testing, refer to Displacement on Demand (DoD) System Diagnosis .

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If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List. The other option is to refer to Testing for Intermittent Conditions and Poor Connections .

Circuit/System Testing

1. Remove the underhood fuse block cover
2. With the ignition ON and the engine OFF, test for ignition 1 voltage at both test points of the ENG 1 fuse.

⇒	If ignition 1 voltage is available to only one test point of the ENG 1 fuse, test and repair for a short to ground in the ignition 1 voltage circuit to the valve lifter oil manifold (VLOM) assembly.

⇒	If ignition 1 voltage is not available to either test point of the ENG 1 fuse, test and repair the powertrain relay or the relay load circuit for an open or high resistance condition.

Important: The presence of battery voltage on the ignition 1 voltage circuit to the VLOM connector does not assume that the circuit is free of any high resistance. High resistance could develop anywhere within a circuit, such as in connectors, wiring, relays, solenoids, sensors, modules, or controllers. The first place to test for high resistance would be at any connection point in the circuit. Particular attention should be focused on loose fitting, corroded, or dirty terminals.

3. To test for total circuit resistance or normal circuit operation, perform the following test:

•	With the ignition ON and the engine OFF, measure and record the ignition 1 voltage at the ENG 1 fuse.

•	Remove the ENG 1 fuse from the underhood fuse block.

•	Install a DMM, in series with one 15-amp fused jumper wire and one none fuse jumper wire, across the exposed ENG 1 fuse terminals in the underhood fuse block.

•	Set-up and select the 10-amp range on the DMM.

•	Zero out the DMM display.

•	With a scan tool, command each DoD cylinder ON, one at a time.

•	Record each amperage reading displayed on the DMM.

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To calculate the resistance for each solenoid circuit, divide the previously recorded voltage by the amperage for each DoD solenoid circuit. For example, 12 volts divided by 1-amp of current equals 12 ohms of circuit resistance. The total resistance for each solenoid circuit should be within 11-22 ohms.

⇒	If the total circuit resistance exceeds 22 ohms, an open or a high resistance condition exists somewhere in the ignition 1 voltage circuit, control circuit, solenoid, or the ECM.

4. 4. With the ignition OFF, reinstall the ENG 1 fuse into the underhood fuse block.
5. Disconnect the wire harness electrical connector at the VLOM assembly. With the ignition ON and the engine OFF, test for battery voltage on the ignition 1 voltage circuit at the VLOM wire harness electrical connector.

⇒	If the voltage measures less than battery voltage, test and repair the open/high resistance condition in the ignition 1 voltage circuit. All wire circuit resistance should measure less than 2 ohms.

6. With the ignition ON and the engine OFF, connect one end of a test lamp to the battery positive terminal at the battery. Probe the control circuit for each solenoid at the VLOM wire harness electrical connector.

⇒	If the test lamp illuminates ON for any control circuit, test and repair that control circuit for a short to ground condition. If each control circuit tests normal, replace the ECM.

7. With the ignition ON and the engine OFF, connect one end of the test lamp to the battery positive terminal at the battery. Probe each solenoid control circuit at the VLOM wire harness electrical connector. With a scan tool, command the solenoid ON for the circuit that is being probed.

⇒	If the test lamp does not illuminate when commanded ON, test and repair the control circuit for an open or high resistance condition. All wire circuit resistance should measure less than 2 ohms. If each control circuit tests normal, replace the ECM.

8. With the ignition ON and the engine OFF, connect one end of the test lamp to the battery negative terminal at the battery. Probe the control circuit for each solenoid at the VLOM wire harness electrical connector.

⇒	If the test lamp illuminates ON for any control circuit, test and repair the control circuit for a short to battery voltage condition. If each control circuit tests normal, replace the ECM.

Component Testing

1. With the ignition OFF, disconnect the VLOM wire harness electrical connector. Connect the cable that is labeled POWER from the displacement on demand (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 time, on the DoD tester. Monitor the DMM display.

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

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.