I need to replace a regular push button call switch for an elevator (the lobby call button/ switch) with a keyed switch (to enhance security). The push button switch has four wires connected to it. Since the button lights up when depressed (pushed), and stays lit until the elevator arrives, I assume that two of the four wires control the light in the switch and the other two wires actually call the elevator. The new key switch will not light up when activated. Therefore I will have two extra wires that I will wire nut and dead end (the ones for the light). How can I tell which wires are what and how do I hook up the two remaining wires as there are four screws on the back of the switch/contactor. Anybody know??

You could shut off power to elevator, identify wires on existing switch, then check for pushbutton operation with a continuity or voltmeter, see what 2 wire were on the 2 contact points. Hook thos 2 wires to the new keyswitch, Momentary operation, right?