Diagnostic Instructions

DTC Descriptors

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

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 System Command

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Vehicle traveling at 40 mph, under a light load and steady throttle input Normal Range: V4 mode
Cylinder Deactivation System Command	V8 mode	V8 mode	--

Cylinder 1, 4, 6, 7 Deactivation Solenoid Command

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Vehicle traveling at 40 mph, under a light load and steady throttle input Normal Range: ON
Cylinder 1, 4, 6, 7 Deactivation Solenoid Command	OFF	OFF	--

Cylinder 1, 4, 6, 7 Deactivation Solenoid Circuit Status

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Vehicle traveling at 40 mph, under a light load and steady throttle input Normal Range: Incomplete or OK
Cylinder 1, 4, 6, 7 Deactivation Solenoid Circuit Status	Short to GRD/Open	Short to GRD/Open	--

Cylinder Deactivation Performance

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Vehicle traveling at 40 mph, under a light load and steady throttle input Normal Range: OK
Cylinder Deactivation Performance	Fault	Fault	--

Circuit/System Description

Each of the four valve lifter oil manifold (VLOM) solenoid windings, are connected in parallel to a fused ignition circuit, supplied by the powertrain relay, in the underhood fuse block. The 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, or short to ground 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. These DTCs will set when the ECM detects an incorrect voltage level on the ignition circuit, the solenoids, or a solenoid control circuit, after the ignition switch is turned ON. If a VLOM solenoid control circuit DTC is set, the ECM will command V8 mode, turn ON the malfunction indicator light (MIL), and turn OFF the fuel injector for that cylinder, resulting in an engine misfire.

Conditions for Running the DTC

Conditions for Setting the DTC

Action Taken When the DTC Sets

Conditions for Clearing the DTC

DTC P3401, P3425, P3441, and P3449 are type B DTCs.

Diagnostic Aids

The VLOM solenoids are assigned to the following engine cylinders:

Important: This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to 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 10A 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, an open/high resistance condition exists in the VLOM solenoid circuit.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Description and Operation

Cylinder Deactivation (Active Fuel Management) System Description

Electrical Information Reference

Mechanical Information Reference

Cylinder Deactivation (Active Fuel Management) System Diagnosis

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Special Tools Required

EN-46999 Displacement On Demand Tester

Circuit/System Verification

Ignition ON, engine OFF, command each VLOM solenoid ON and OFF several times using the scan tool. Listen for the VLOM solenoids to turn ON and OFF.

Circuit/System Testing

Important: Perform the Circuit/System Verification first.

1. Ignition OFF, remove the fuel pump fuse or the fuse for the fuel system control module.
2. Perform the Fuel Pressure Relief .
3. Remove the Intake Manifold.
4. Disconnect the VLOM harness connector.
5. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal E, and ground.

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test or replace the VLOM assembly.

6. Connect a test lamp between the appropriate control circuit terminal and the ignition circuit terminal E.
7. Command the VLOM solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to ground. If the circuit test normal, replace the ECM.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ECM.

8. If all circuits test normal, test or replace the VLOM assembly.

Component Testing

Important: Perform the Circuit/System Testing first.

Static Test

1. Ignition OFF, disconnect the VLOM harness connector at the VLOM assembly.
2. Connect the cable that is labeled resistance from the EN-46999 to the VLOM connector.
3. Connect the power leads from the EN-46999 to B+ and ground. Test for 11-18 ohms of resistance on each VLOM solenoid.

⇒	If the resistance is not within the specified range for each solenoid, replace the VLOM assembly.

4. Test for infinite resistance between each VLOM circuit terminal and the VLOM housing.

⇒	If less than infinite resistance, replace the VLOM assembly.

Dynamic Test

1. Ignition OFF, disconnect the VLOM harness connector at the VLOM assembly.
2. Connect the cable that is labeled power from the displacement on demand EN-46999 to the VLOM connector.
3. Connect the power leads from the EN-46999 to B+ and ground.
4. Command each VLOM solenoid ON and OFF using the EN-46999 . You should be able to hear each solenoid turn ON and OFF.

⇒	If the function does not perform as specified, replace the VLOM assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.