Circuit/System Testing
- Ignition OFF, disconnect the vacuum hose at the vacuum actuator.
- Connect a J 23738-A
to the port of the vacuum actuator. Apply 51 kPa (15 Hg) 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.
- Disconnect the harness connector of the IMT valve solenoid.
- Ignition ON, verify a test lamp illuminates between the ignition 1 voltage circuit and ground.
- If the test lamp does not illuminate, repair the ignition 1 voltage circuit for a short to ground or an open/high resistance. Replace the fuse, if necessary.
- Ignition OFF, connect a test lamp between the control circuit and the ignition 1 voltage circuit.
- Ignition ON, command the IMT valve solenoid ON and OFF with a scan tool. The test lamp should turn ON when the solenoid is commanded OFF, and OFF when the solenoid is commanded ON.
- If the test lamp remains ON all the time, test for a short to ground on the control circuit. If circuit/connections test normal, replace the ECM.
- If the test lamp remains OFF all the time, test for a short to voltage or an open/high resistance on the control circuit. If circuit/connections test normal, replace the ECM.
- Connect the vacuum hose to the vacuum actuator.
- Connect the harness connector of the IMT valve solenoid.
- Disconnect the vacuum supply hose from the intake manifold.
- Connect a J 23738-A
to the vacuum supply hose. Apply 51 kPa (15 Hg) of vacuum to the vacuum supply hose. Engine idling, verify that the vacuum decreases.
- If the vacuum does not decrease, repair the restriction, or replace the IMT valve solenoid.
- Engine idling, monitor the vacuum display. Verify that the vacuum stabilizes and remains steady.
- If the vacuum decreases, repair the vacuum leak.
IMPORTANT:
The vacuum displayed on the J 23738-A
should decrease after engine start, and then stabilize.