Which 3 way switch isn't working

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  #1  
Old 11-05-15, 04:44 PM
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Question Which 3 way switch isn't working

Two 3 ways controlling light. Both used to work fine. All of a sudden, Switch A will turn the light on or off only when Switch B is in the on position (up). When Switch B is down Switch A will not work at all. Switch A will turn the light on only if Switch B is in the on position (up) but not if B is in the down position. How can I determine which one is defective?
 
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Old 11-05-15, 05:18 PM
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With 3 way switches, either up or down can be on. You need to inspect each switch & test them with a tester. Maybe switch B has a lose wire. Are there any dimmers involved? If so, replace it with a new 3 way switch.
 
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Old 11-05-15, 05:31 PM
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Welcome to the forums.

It sounds like B is the problem switch. Usually I'll change them in pairs.
 
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Old 11-05-15, 05:48 PM
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Be sure to mark the common wire at each switch. The common terminal on the new switch may or may not be in the same location as on the old switch so be sure which terminal is common on the new switch.
 
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Old 11-05-15, 05:57 PM
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Excellent point Ray
 
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