Overall Function Test

Disconnect vacuum hose to fuel pressure regulator and attach to a vacuum gauge. Disconnect intake valve timing control solenoid harness connector. Start engine and warm to operating temperature. Increase engine speed to 3000 RPM and hold when vacuum is steady. While monitoring vacuum gauge, apply battery voltage to intake valve timing control solenoid. See Figure. If vacuum drops at least .39 in. Hg, system is okay. If vacuum does not drop at least .39 in. Hg, go to procedure.