Celica, Corona and Pickup
Connect a vacuum gauge to distributor main advance diaphragm hose. Start engine, and pinch hose on carburetor side of VTV. Increase engine speed to 2000 RPM and release hose. Vacuum should rise to more than 4 in. (100 mm) Hg in 0.5 - 2 seconds. Disconnect hose between VTV and advancer port. Vacuum should drop quickly. Remove distributor cap and apply vacuum at advance diaphragms and check for movement of base plate.