Intake Manifold Tuning (IMT) Valve Diagnosis

INTAKE MANIFOLD TUNING (IMT) VALVE DIAGNOSIS

DIAGNOSTIC FAULT INFORMATION
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
An intake manifold tuning (IMT) valve or variable geometry induction system (VGIS) 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. Ignition 1 voltage is supplied directly to the IMT valve solenoid. The engine control module (ECM) controls the solenoid by grounding the control circuit. The IMT system contains the following components:
- The IMT valve solenoid
- The IMT valve position sensor
- The IMT valve vacuum reservoir
- The IMT valve vacuum actuator
- The intake manifold tuning valve
- The intake manifold

CIRCUIT/SYSTEM VERIFICATION
1. Engine idling, verify that DTC P0660 is not set.
- If the DTC is set, refer to DTC P0660. P0660
2. Engine idling, command the IMT valve ON with a scan tool. The IMT valve vacuum actuator should move to the closed position.

CIRCUIT/SYSTEM TESTING
1. Verify that none of the following conditions exist:
- Disconnected, restricted, or damaged vacuum hoses
- Disconnected or damaged components
- Binding vacuum actuator linkage
- Linkage that is interfering with hoses, wiring, or any other components
- Internally binding IMT valve-Refer to Intake Manifold Replacement.
- If you find any of the above conditions, repair as necessary.
2. Ignition OFF, disconnect the vacuum supply hose at the vacuum reservoir.
3. Engine idling, connect a J 23738-A to the supply hose of the vacuum reservoir and verify the vacuum is greater than 33 kPa (10 Hg).
- If less than 33 kPa (10 Hg) of vacuum, repair the leak or restriction in the supply hose of the vacuum reservoir.
4. Ignition OFF, connect a J 23738-A to the supply port of the vacuum reservoir and disconnect the outlet hose of the vacuum reservoir and plug the outlet port. Verify that the vacuum reservoir holds vacuum.
- If the vacuum does not hold, replace the vacuum reservoir.
5. Ignition OFF, connect the vacuum hoses to the vacuum reservoir.
6. Disconnect the vacuum supply hose at the IMT valve solenoid and connect a J 23738-A to the vacuum supply hose at the IMT valve solenoid.
7. Engine idling, verify the vacuum is greater than 33 kPa (10 Hg).
- If less than 33 kPa (10 Hg) of vacuum, repair the leak or restriction in the supply hose of the IMT valve solenoid.
8. Ignition OFF, connect the supply hose to the IMT valve solenoid and disconnect the outlet hose at the IMT valve solenoid.
9. Engine idling, connect a J 23738-A to the outlet hose at the IMT valve solenoid and verify the vacuum is greater than 33 kPa (10 Hg).
- If less than 33 kPa (10 Hg) of vacuum, replace the IMT valve solenoid.
10. Ignition OFF, connect the outlet hose to the IMT valve solenoid.
11. Disconnect the supply hose at the vacuum actuator and connect a J 23738-A to the outlet hose at the IMT valve solenoid.
12. Engine running, verify the vacuum is greater than 33 kPa (10 Hg).
- If less than 33 kPa (10 Hg) of vacuum, test for a leak or restriction in the supply hose of the vacuum actuator.
- If more than 33 kPa (10 Hg) of vacuum, replace the vacuum actuator.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests