1979 Celica, Corona & Pickup

With cold engine, disconnect distributor hose and connect vacuum gauge. Vacuum should change as throttle is opened and closed. Warm engine and pinch hose from advancer port to thermal vacuum switch. Raise engine speed to 2000 RPM, release hose, and check that vacuum rises within 2-4 seconds. Disconnect hose from advancer port. Vacuum should drop quickly to zero.