For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### 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 Parameter 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 Parameter Normal Range: ON
Cylinder 1, 4, 6, 7 Deactivation Solenoid Command | OFF | OFF | --

#### 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 Parameter Normal Range: OK
Cylinder Deactivation Performance | Fault | Fault | --

### Circuit/System Description

Each of the 4 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

• | The engine speed is greater than 400 RPM.

• | The ignition voltage is between 9-18 volts.

• | DTC P3401, P3425, P3441, and P3449 runs continuously when the above conditions are met.

### Conditions for Setting the DTC

• | The ECM detects that the commanded state of the low side driver and the actual voltage level of the control circuit do not match.

• | The condition is present for 20 out of 25 sample counts.

### Action Taken When the DTC Sets

• | DTC P3401, P3425, P3441, and P3449 are Type B DTCs.

• | The engine will return to V8 mode.

• | The fuel injector will turn OFF for the cylinder that has a cylinder deactivation DTC set, resulting in an engine misfire.

### 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:

• | Solenoid #1 = Cylinder #1

• | Solenoid #2 = Cylinder #4

• | Solenoid #3 = Cylinder #6

• | Solenoid #4 = Cylinder #7

Important: This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test.

1. Remove and inspect the fuse for the valve lifter oil manifold assembly.

⇒ | If the fuse is open, then a short to ground condition exists in the circuit.

2. Ignition ON, engine OFF, measure and record the ignition voltage at the fuse for the valve lifter oil manifold (VOLM) assembly.
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.

⇒ | If zero current is detected, then an open circuit condition exists in the circuit.

7. Calculate the resistance for each 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 circuit.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Cylinder Deactivation (Active Fuel Management) System Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

#### Special Tools

EN-46999 Displacement On Demand Tester

### Circuit/System Verification

1. Engine running, command the affected cylinder deactivation solenoid ON and OFF, with a scan tool, while observing the following cylinder deactivation control circuit status parameters.

• | Cylinder 1, 4, 6, or 7 solenoid control Ckt. Short Gnd Test Status

• | Cylinder 1, 4, 6, or 7 solenoid control Ckt. Open Test Status

• | Cylinder 1, 4, 6, or 7 solenoid control Ckt. Short Volts Test Status

• | Each parameter should toggle between OK and Not Run or Not Run and OK

2. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

Important: You must perform the Circuit/System Verification first.

1. Disconnect the valve lifter oil manifold (VOLM) harness connector.
2. 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.

3. Verify that a test lamp does not illuminate between the ignition circuit terminal E and the affected control circuit terminal.

⇒ | If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Remove the test lamp.
5. Command the affected cylinder deactivation solenoid ON with a scan tool. Verify with a scan tool that the affected cylinder deactivation solenoid Ckt. Short Volts Test Status parameter is OK.

⇒ | If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

6. Install a 3A fused jumper wire between the affected control circuit terminal and the ignition circuit terminal E. Command the affected cylinder deactivation solenoid ON with a scan tool. Verify with a scan tool that the affected cylinder deactivation solenoid Ckt. Short Volts Test Status parameter is displaying Fault.

⇒ | If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

7. If all the circuits test normal, test or replace the VOLM 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 displacement on demand (DoD) tester to the VLOM connector.
3. Connect the power leads from the DoD tester to B+ and ground. Test for 11-18 ohms 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 DoD tester to the VLOM connector.
3. Connect the power leads from the DoD tester to B+ and ground.
4. Command each VLOM solenoid ON and OFF using the DoD tester. 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

• | Engine Control Module Programming and Setup

• | Engine Control Module Replacement

### Repair Verification

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.
5. Engine running, command each cylinder deactivation solenoid ON and OFF with a scan tool, while observing the cylinder deactivation circuit status parameters. The circuit status parameters should change from OK to NOT Run or Not Run to OK.

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