Diagnostic Instructions

DTC Descriptors

DTC P2076: Intake Manifold Tuning (IMT) Valve Position Sensor Performance

DTC P2077: Intake Manifold Tuning (IMT) Valve Position Sensor Circuit Low Voltage

DTC P2078: Intake Manifold Tuning (IMT) Valve Position Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Ignition Voltage	P2009*	P2008	--	P2076
IMT/IMRC Control Circuit	P2009, P2076	P2008	P2010	P2076
IMT/IMRC Signal Circuit	P2077	P2076, P2077, P2078	P2076, P2077, P2078	P2076
IMT/IMRC Ground	--	P2076, P2077, P2078	--	P2076
*Opens the fuse that supplies voltage to the IMT/IMRC solenoid.

Circuit/System Description

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 two smaller plenums. The IMT valve improves engine performance at low and high engine speeds.

Ignition voltage is supplied directly to the IMT solenoid. The engine control module (ECM) controls the solenoid by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

The IMT valve also contains a position sensor which is used to detect the actual position of the IMT valve in relation to its commanded position. The ECM supplies the IMT position sensor with a 5-volt signal circuit and the position sensor uses a common ground circuit. The position sensor enables the ECM to detect a physically broken or stuck IMT valve.

Conditions for Running the DTC

Conditions for Setting the DTC

The ECM detects that the commanded state of the IMT driver and the position sensor signal do not match for greater than 4 seconds, or for cumulative of 50 seconds.

Action Taken When the DTC Sets

DTCs P2076, P2077, and P2078 are Type B DTCs.

Conditions for Clearing the DTC

DTCs P2076, P2077, and P2078 are Type B DTCs.

Diagnostic Aids

If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan tool circuit test status parameters for the component. A circuit test status parameter will change from OK or Not Run to Fault if there is a condition with the circuit or a connection.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Air Intake 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

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify DTC P2008, P2009, or P2010 is not set.

⇒	If a DTC is set, refer to DTC P2008, P2009, or P2010.

2. Command the IMT solenoid ON and OFF with a scan tool. You should hear and feel an audible click.

⇒	If no audible click is heard, refer to Intake Manifold Runner Control System Diagnosis.

3. Observe the DTC information with a scan tool. DTC P2076, P2077, or P2078 should not fail this ignition.
4. 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 solenoid.
2. Test for less than 5 ohms between the ground circuit terminal B and battery ground.

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

3. Ignition ON, test for 4.8-5.2 volts between the IMT signal circuit terminal D and ground.

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

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

4. If all circuits test normal, replace the IMT solenoid.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.