Diagnostic Instructions
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 vacuum reservoir |
• | The IMT valve vacuum actuator |
• | The intake manifold tuning valve |
Reference Information
Description and Operation
Air Intake System Description
Special Tools
J 23738-A
Vacuum Pump
Circuit/System Verification
- Engine running, observe the DTC Information with a scan tool. Verify that DTC P0660, P0661, or P0662 is not set.
- Engine running, command the IMT valve ON with a scan tool. The IMT valve vacuum actuator should move to the closed position.
Circuit/System Testing
- Ignition OFF, disconnect the vacuum hose at the IMT valve vacuum actuator.
- Connect a
J 23738-A
to the port of the vacuum actuator. Apply 51 kPa (15 inches H2O) of vacuum to the vacuum actuator. Verify the vacuum actuator moves, and that the vacuum remains
steady.
⇒ | If the vacuum actuator does not move, replace the vacuum actuator. |
⇒ | If the vacuum decreases, replace the vacuum actuator. |
- Connect the
J 23738-A
to the vacuum supply hose of the IMT valve vacuum actuator.
- Engine running, test for greater than 28 mm Hg (15 inches H2O).
⇒ | If less than the specified range, test for the following conditions: |
• | A leak in the vacuum hoses, lines, or vacuum storage tank. |
• | A blockage or restriction in hoses, lines, or vacuum storage tank. |
• | A blockage or restriction at the intake manifold vacuum port |
⇒ | If no condition is found, replace the IMT valve solenoid. |
- Engine running, disconnect the IMT solenoid electrical connector. Verify the vacuum remains steady for 30 seconds.
⇒ | If the vacuum decreases, replace the IMT valve solenoid. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.