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 valve system contains the following components:

Description and Operation

Air Intake System Description

Special Tools Required

J 23738-A Mityvac

1. Engine running, verify that DTCs P1181 or P1182 are not set.

⇒	If either DTC is set, refer to DTC P1181 or P1182 .

2. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records data list.

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 .

2. Ignition OFF, disconnect the vacuum supply hose at the vacuum reservoir.
3. Connect a J 23738-A to the supply hose of the vacuum reservoir.
4. Engine running, test for 33 kPa (10 Hg) of vacuum.

⇒	If less than 33 kPa (10 Hg) of vacuum, test for a leak or restriction in the supply hose of the vacuum reservoir.

5. Ignition OFF, connect a J 23738-A to the supply port of the vacuum reservoir.
6. Disconnect the vacuum outlet hose at the vacuum reservoir.
7. Plug the vacuum outlet port of the vacuum reservoir, while applying vacuum to the vacuum reservoir.

⇒	If the vacuum does not hold, replace the vacuum reservoir.

8. Ignition OFF, connect the vacuum hoses to the vacuum reservoir.
9. Disconnect the supply hose at the IMT valve solenoid.
10. Connect a J 23738-A to the vacuum supply hose at the IMT valve solenoid.
11. Engine running, test for 33 kPa (10 Hg) of vacuum.

⇒	If less than 33 kPa (10 Hg) of vacuum, test for a leak or restriction in the supply hose of the IMT valve solenoid.

12. Ignition OFF, connect the supply hose to the IMT valve solenoid.
13. Disconnect the outlet hose at the IMT valve solenoid.
14. Connect a J 23738-A to the outlet hose at the IMT valve solenoid.
15. Engine running, test for 33 kPa (10 Hg) of vacuum.

⇒	If less than 33 kPa (10 Hg) of vacuum, replace the IMT valve solenoid.

16. Ignition OFF, connect the outlet hose to the IMT valve solenoid.
17. Disconnect the supply hose at the vacuum actuator.
18. Connect a J 23738-A to the outlet hose at the IMT valve solenoid.
19. Engine running, test for 33 kPa (10 Hg) of vacuum.

⇒	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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.