1. Start the engine at idle, then raise the air bypass tube closer to the throttle body and check that the engine slows down.
2. If the engine is cold and does not slow down, check the hoses for leaks and check the air valve as described in steps 3 - 6. If the engine is hot and the decrease is more than 200 rpm, disconnect the electrical wiring connector from the valve and pull off the rubber boot. With the ignition on, use a voltmeter to check that there is voltage at the GR connector terminal. If not, check wiring and relay.
3. With the connector removed, use an ohmmeter to check the resistance at the pneumatic valve clamps - 30-45 Ohm,
4. Install the connector.
5. With the two hoses disconnected, turn on the ignition and check if the engine is cold the valve is open or if the engine is hot the valve is closed.
6. Turn off the ignition and install the hoses.