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 P0661: Intake Manifold Tuning (IMT) Valve Solenoid Control Circuit Low Voltage.
DTC P0662: Intake Manifold Tuning (IMT) Valve Solenoid Control Circuit High Voltage.

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Ignition 1 Voltage Circuit | P0661 | P065E | P0661 | -- | --
IMT Valve Actuator Solenoid Control Circuit | P0661 | P065E | P0661 | P0662 | P065E

### Circuit/System Description

The intake manifold tuning (IMT) valve system uses variable air induction tuning in order to achieve maximum performance and efficiency over the entire operating range of the engine. The characteristic torque curve of a normally aspirated engine depends mainly on how the engines average pressure changes over the engine speed range. The average pressure is proportional to the volume of the air mass present in the cylinder when the inlet valve is closed. The design of the inlet system determines how large an air mass can be drawn into a cylinder at a given engine speed. An IMT valve is used to change the intake manifold plenum configuration. When the IMT valve is open, the intake manifold is configured to one large plenum. When the IMT valve is closed, the intake manifold is configured to 2 smaller plenums. The 2 intake manifold plenum sizes result in different torque curves, which improves performance at low and high engine speeds. During low speed, high load conditions the IMT valve is closed creating a longer runner path inside the plenum, which increases torque. During higher engine speeds and loads, the IMT valve opens creating a shorter runner path inside the plenum, which increases horsepower.

The IMT valve actuator solenoid has the following circuits:

• | Ignition 1 voltage

• | IMT Valve Actuator Solenoid Control

### Conditions for Running the DTCs

• | DTC P0606 is not set.

• | The ignition is ON, or the engine is running.

• | The battery voltage is greater than 9 volts.

• | This DTC runs continuously within the enabling conditions.

### Conditions for Setting the DTCs

#### P0661

The ECM detects a short to ground or an open on the IMT valve actuator solenoid control circuit for greater than 2 seconds.

#### P0662

The ECM detects a short to voltage on the IMT valve actuator solenoid control circuit for greater than 2 seconds.

### Action Taken When the DTCs Set

DTCs P0661 and P0662 are Type B DTCs.

### Conditions for Clearing the MIL/DTCs

DTCs P0661 and P0662 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### 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.

### Circuit/System Verification

1. Use the scan tool output controls to command the IMT Valve Actuator Solenoid parameter ON and OFF. Verify that the diaphragm arm moves at least once when there is sufficient vacuum in the storage tank.
2. Use the scan tool output controls to command the IMT Valve Actuator Solenoid parameter ON and OFF. An audible click should be heard and felt.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the IMT valve actuator solenoid.
2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 2 and ground.

⇒ | If the test lamp does not illuminate test the ignition circuit for a short to ground or an open/high resistance.

3. Connect a test lamp between the control circuit terminal 1 and the ignition circuit terminal 2.
4. Command the IMT valve actuator 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 tests 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.

5. If the circuits test normal, test or replace the IMT valve actuator solenoid.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Intake Manifold Tuning Valve Actuator Solenoid Replacement

• | Control Module References for ECM replacement, setup, and programming