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 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

• | The ignition is ON or the engine is operating.

• | The IMT solenoid has been commanded ON and OFF at least once during the ignition cycle.

• | The DTCs run continuously once the above condition is met.

### 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

• | 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. 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.

• | Intake Manifold Runner Control Solenoid Replacement

• | Control Module References for engine control module replacement, setup, and programming