New answers tagged troubleshooting
As you probably know, standard three-way switches have two "traveler" wires running between them. The problem you describe can indicate that one of the travelers has become disconnected. The result is equivalent to two standard switches in series. I expect that when you check the switches, you'll find a wire has come off its screw or out of the backstab.
I had a similar problem on a circuit with two switches for one light. It turned out to be that one switch only completed the circuit in one position, as though it were a simple on/off switch. Replacing the defective switch solved the problem.
You have a simple mis-wire somewhere. As previously stated, you need to open both switches and see how everything is wired. Get a few good diagrams of common 3-way wiring patterns and see if one is like the way yours are wired. A Google search will bring up many. The position of the switches does NOT matter at all. What matters is identifying the feed wire, ...
Top 50 recent answers are included