1.   Before disconnecting the three-way switch, examine each terminal screw.

2.   A three-way switch has three terminal screws.

3.   But because they have three terminal screws the wiring is a little more complicated.

4.   But to be on the safe side do not touch any wires or terminal screws until testing the power.

5.   Connect a black lead to the brass terminal screw and a white wire to the silver terminal.

6.   Disconnect the wires from the terminal screws and tie a length of cord to the end of this wire before you pull the wire out from the bottom.

7.   Loosen the terminal screws on the socket to disconnect it from the wires.

8.   Make sure that all the wires are connected and the terminal screws are tight.

9.   Most dimmers do not have terminal screws.

10.   Then touch the other probe to each terminal screw.