In a Z with automatic transmissions the WOT switch is used for forcing a downshift into the lowest possible gear ratio if the throttle pedal is fully depressed. This is referred to as "throttle kickdown" and is in response to an abrupt increase in engine power. As an example, lets say you are driving at 55 mph and you have your automatic overdrive switch engaged. You then floor the throttle which engages the WOT switch. The switch tells the A/T control unit to change into the lowest possible gear ratio taking it out of overdrive mode.