An intake manifold tuning (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 IMT valve improves engine performance at low and high engine speeds depending on the engine load. The IMT valve assembly consists of the following:

Ignition Voltage Circuit

An ignition voltage is supplied directly to the IMT valve assembly from the powertrain relay through a 10A fuse. The ignition voltage provides power to a microprocessor and to a motor that rotates the IMT valve within the intake manifold.

Ground Circuit

Ground circuit is supplied directly to the IMT valve assembly. This circuit provides ground for the micro-processor and the motor.

IMT Valve Control Circuit

During operation when the valve is open, the control module applies ground to the IMT valve control circuit which indicates to the microprocessor within the IMT valve to position the valve to the closed position which turns the motor ON and rotates the IMT valve within the intake manifold plenum.

IMT Valve Signal Circuit

When the IMT valve is rotated the hall-effect sensor is reporting the position of the valve to the engine control module (ECM). The control module uses this feedback signal to determine the position of the IMT valve.

The control module compares the commanded state of the IMT valve control circuit to the IMT valve signal circuit for being stuck open, stuck closed.

The ECM detects that the commanded state and the actual state of the IMT valve control circuit do not match. The ECM will detect an open, short to ground or short to voltage on the IMT valve control. It will also set a DTC if the IMT valve ignition voltage circuit is open, or short to ground. Each condition for more than 6.25 seconds.

DTC P0660 is a Type C DTC.

DTC P0660 is a Type C DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Intake Manifold Tuning Valve System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON engine OFF.
2. Command the IMT valve ON and OFF. The IMT valve Command parameter should transition from open to closed, and the IMT valve Feedback parameter should transition from 18.4-25.2 percent to 76.3-83.2 percent.

1. Ignition OFF, disconnect the IMT valve harness connector at the IMT valve.
2. Test for less than 1 ohm between the IMT valve ground circuit terminal B and ground.

⇒	If greater than the specified value, test the ground circuit for an open/high resistance.

3. Ignition ON, verify that a test lamp illuminates between the IMT valve ignition 1 voltage circuit and ground.

⇒	If the test lamp does not illuminate, test the IMT valve ignition 1 voltage circuit terminal A for a short to ground or an open/high resistance. If the circuit tests normal and the fuse for the IMT valve ignition 1 voltage circuit is open, test or replace the IMT valve.

4. Verify that test lamp does not illuminate between B+ and the IMT valve control circuit terminal C.

⇒	If the test lamp illuminates, test the control circuit for a short to ground.

5. Remove the test lamp.
6. Command the IMT Valve ON with a scan tool. Verify the scan tool IMT Valve Sol 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.

7. Install a 3A fused jumper wire between the IMT valve control circuit terminal C and B+. Command the affected IMT Valve ON with a scan tool. Verify the scan tool IMT Valve Sol Ckt. Short Test Status Parameter is Fault.

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

8. Ignition ON, test for 4-6 volts between the IMT valve signal circuit terminal D and ground.

⇒	If less than the specified range, test the IMT valve signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

⇒	If greater than the specified range, test the IMT valve signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

9. Install a 3A fused jumper wire between the IMT valve signal circuit terminal D and ground. Verify the scan tool IMT valve Feedback parameter transitions from 0-100 percent.

⇒	If parameter does not change, test the IMT valve signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

10. If all circuits test normal, test or replace the IMT valve.

Note: If at any time the IMT valve blade becomes separated from the actuator, DO NOT cycle the actuator. Cycling the actuator without the blade attached will offset the calibration, and the entire IMT valve assembly will need to be replaced.

1. Remove the IMT valve.
2. Connect the IMT valve harness connector.
3. Turn ON the ignition and command the IMT valve ON and OFF using a scan tool. The IMT valve should rotate quickly from one position to another.

Note: If at any time the IMT valve blade becomes separated from the actuator, DO NOT cycle the actuator. Cycling the actuator without the blade attached will offset the calibration, and the entire IMT valve assembly will need to be replaced.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.