Checking functionality
1. Start the engine and allow it to warm up to operating temperature. Disconnect the EACV hose from the air cleaner and, with the engine speed reaching approximately 3500 rpm, feel for vacuum in the hose with your hand. Quickly close the throttle valve and again feel for vacuum in the hose.
2. If there is vacuum in the hose and the CHECK ENGINE light is not on, then the EACV mechanism is working properly. If there is no vacuum in either case, and the CHECK ENGINE light is not on, then there is an air leak between the EACV and the intake manifold, or the EACV mechanism is not working properly.
3. Turn off the engine and remove the EACV electrical connector. Check the resistance between the terminals, it should be 8-15 ohms. Also check the resistance between each terminal and ground, it should be infinite (no contact with ground). If any of these tests are negative, then the EACV should be replaced.
4. Pull out the main connector of the ECU and check the wiring between terminals A1 and A3 of the EACV and the ECU. With the terminals of the EACV connected to each other, the resistance between the specified terminals A1 and A3 should be 815 ohms. Also check for a good ground connection between terminals A24 and A26.
5. If all tests are positive, remove the ECU fuse located in the relay box under the engine hood for 10 seconds to clear the fault codes. Then test drive the vehicle and check if the EACV still malfunctions. If you have a tested and working ECU, you should install it when performing the road test.