Lighting, Light Fixtures, Ceiling and Exhaust Fans - 2 switches one light

I have a house that is about 100 years old and the upstairs wiring is in good shape but does not have grounds. All of the wiring for the switch in question is black and I am having problems getting both switches to work properly. While both switches will work they do not both work at the same time. If the upstairs switch is on the bottom one is inactive and vice versa. If the upstairs switch is on I am only getting 43 volts at the bottom switch. If off, I am getting 110. Since I do not have a ground wire getting proper readings on the individual wires is a problem


any ideas?

You can not take meaningful voltage readings from a wire connected to a switch in most cases even if you did have a ground. Has this setup ever worked to your knowledge? Did you make any recent changes?

There should be at least three wires in each box. Is your house still wired with knob and tube wiring (individual cloth covered wires)? If so you may have an unsafely wired three-way. Let us know how many wires in each switch box, screw colors on the switches, and all the wires at the light ,and how they are connected. Be very careful. If this is K&T the insulation may crumble off.

While the upstairs is wired with K&T, it was checked out by an electrician when the downstairs and panel were upgraded. It was said to be in good shape with solid insulation.

Should each of the two sitches always have 120 volts or is one of the two switches a considered a main switch?

Yes, both switches worked properly and I fear that the problem is related to upgrading the switches to lighted ones.

Also in answer to your question, all of the wires are black and there are 3 at each switch.

Regardless of switch position to on or off, should both switches always have one wire that has 120 volts?

If all of the wires are the same color how did you determine which wire went where? The wire on the black screw of the old switch should have went to the black screw on the new one. If i twas a very old switch the screw would have been the odd colored screw or marked with a "c" or marked "common".

Do the new lighted switches have four screws?

Note: I'm sure you know 3-way switches have no top or bottom or left or right so those terms are meaningless when connecting a new switch.

If there are only three wires at each switch then power for the light, probably comes into the light Jbox not either switch. Measuring voltage at the switch doesn't really tell you much..

The problem started when someone was helping me with a repair project on the wall and in the process put in a new lighted switch. Since all of the wires are black I can only asume that he switched the wires. I have put in 3-way lights in remodeling projects and didn't have any problems because when I did the wiring I used the proper color codes on the wires. The nasty part of the old switch has to do with the only color being black. The biggest help would be if I knew that both switches should always have 110 volts on one of the wires regardless of switch position. Is this the case?

It sounds like you have only replaced the one 3 way switch. If so there are only 2 other combinations to try and get this back to working order. You already know one way that doesn't. I might suggest identifying the wires somehow you you can tell which combinations have been tried.

Do you have any family members, or children that live near by?

I would recommend you spend more time working on their house. Especially if they just bought a fixer upper and have a large to do list!

Just a thought - good luck!