Three-way light switch not working correctly

Symptoms

• Light only turns on/off correctly from one of the two switches
• Light flickers or behaves oddly when either switch is used
• Switch doesn't return to a consistent 'on' or 'off' position

Likely causes

• CommonOne of the two three-way switches has failedThree-way switches have extra internal contacts that can wear out or fail independently.
• CommonA loose traveler or common wire connectionThree-way circuits use extra 'traveler' wires between switches that can loosen over time.
• PossibleIncorrect wiring from a previous repairIf a switch was replaced recently and wires weren't matched to the same terminals, the circuit can behave unpredictably.
• PossibleA failing bulb affecting perceived switch behaviorFlickering can sometimes be the bulb, not the switches.

What to do

1. Test the light with each switch individually to see if one location works fine and the other doesn't.
2. Replace the bulb first if there's flickering, to rule out the simplest cause.
3. Turn off the breaker before opening either switch box.
4. Take a photo of the wire arrangement at each switch before disconnecting anything.
5. Check for a loose or discolored wire at the 'common' terminal (usually a different color screw) or the traveler terminals.
6. If a switch was recently replaced, confirm the common wire was moved to the correct terminal on the new switch.
7. Call an electrician if the wiring is unclear or the problem isn't a simple loose connection.

Tools and parts

• Non-contact voltage tester
• Screwdriver

When to call a pro

Call an electrician if you're unsure which wire is which, or the problem persists after checking connections.

Safety