3 way switch problem, need help

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Old 03-12-19, 08:59 AM
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3 way switch problem, need help

I am visiting a relative and noticed one of the 3 way switches that operates the overhead lights in the garage doesn't work sometimes. suspected a bad switch or loose connections so I thought I would check it.

think I may be a little stumped though and would like some of your feedback. Thanks

there is a switch in the garage and one just inside the house on the opposite side of the same wall that should turn the light on and off. Currently the SW in the garage has to be one for the one inside to operate the lights on or off.

There are 3 wires connected to each SW. 1 red and 2 blacks. the red is connected to single treminal on opposite side of SW than the 2 blacks are. There is no voltage at the red? Is that right?

If I turn off the SW in the garage I have no hot at all to the SW inside the house. Is this right?

Seems like in a 3 way SW set up there should always be a hot to both switches and I should be able to operate the light from either switch no matter what position the other SW is in. Is that not correct?

What do you think I should check next?
Should I replace both switches?
Should there be some kind of voltage to ground on the red wire?

Thanks. I will be here until tomorrow around lunch so any help is appreciated. I would like to get source of problem found before I go.
 
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Old 03-12-19, 09:21 AM
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Screw position means nothing. You need to identify the COMMON screw. It will be labeled or black in colour.
You say you have 2 blacks in each box. That means there must be two cables. One cable will have three wires, black, red, white. The second cable will have only black and white.

The black from the second cable is the one that should be on the COMMON screw at both switches.
 
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Old 03-12-19, 09:35 AM
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as for the screws on the SW, one of the screws is a black one which must be the common one. I read in one place that I should be able to ohm from the common to one of the other "traveller" screws and get continuity to one of those with the SW in one position and continuity to the other when the SW is in the other position. Is this correct? do I need to disconnect all wires from the SW when checking continuity to insure no loop of feedback? thanks for trying to help. I will go take another look at the wires feeding each SW and report back.
 
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Old 03-12-19, 09:41 AM
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the SW that is in the garage has 2 blacks connected to the common screw, and 1 blk and 1 red connected to the 2 travellers.

the SW inside the house has one black connected to the common screw, and 1 blk and 1 red connected to the travellers.

can these SW's be tested better if I just remove all wires and ohm them with nothing connected?
 
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Old 03-12-19, 01:03 PM
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Think I figured it out.

Removed both SW's
checked both, and they checked good.
reterminated all wires to both SW's by attaching wires to screws and not using push-in connections that had previously been used.

Both SW's seem to be working fine now. Thanks for listening and trying to help.
 
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Old 03-12-19, 01:56 PM
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When you have more than one wire on a terminal..... they should be combined with a short tail. The short tail goes to the switch. Using a screw terminal and the push-in usually causes a problem.
 
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