3-Way Switch Only Works When Both Switches Are On? (Fix It Now!)

Heather Robbins
by Heather Robbins

Modern homes are filled with all sorts of electronic conveniences. Many homes come with switches that can turn on a light or device from multiple locations. These switches, called 3-way switches, are a very common convenience in many homes today. But What do you do when the switch is only working when both switches are turned on?

If your 3-way switch only works in one position there is a good chance you have a wiring problem. To solve the problem, troubleshoot the switch by testing the existing wiring and switching the wiring positions. The problem can also be the switch itself, which means you may need to purchase a new 3-way switch.

In order to get your 3-way switch to start functioning the way it was intended to, you first need to find out why it is malfunctioning. There are several potential causes of this issue. Luckily, each issue has troubleshooting techniques and relatively easy ways to resolve the problem.

Understanding What A 3-way Switch Is

A 3-way switch is a pair of switches in two locations that are linked together through wires. The reason for this is that a 3-way switch allows you to turn on or off your lights and ceiling fixtures from two distinct locations.

This means that if you can switch a light on at one end of the room, you can likewise turn it off at the other. This explains why the actual switch has no on/off labels.

Because of the screw terminals, a 3-way switch has a larger body. It contains three terminals and a ground screw in total. Two of the switch’s screw terminals are wired to the other switch– these are called traveler wires. The ceiling or light fixture is typically attached to the other screw terminal.

Steps To Troubleshoot Wiring Of A 3-way Switch

Your 3-way switch should normally function without any issues, and will turn off and on from either location whenever you flip the switch. There are sometimes, however, when your switch may only work if both switches are facing in the same direction. Or perhaps your switch is not turning on at all.

When your 3-way switch is not functioning properly, the first action you should take is to carefully troubleshoot the 3-way switch for connectivity issues following a few simple steps.

Step One: Turn Off Main Power Supply To The Light

Locate the circuit breaker or main power supply and turn it off to ensure you do not get shocked during the troubleshooting process.

Step Two: Label Three Pieces of Tape “1,” “2,” and “3” Respectively

Use a permanent marker to write one number on each of the three pieces of tape.

Step Three: Assign Each Wire A Number Using The Tape

It does not matter which of the three colored live wires you assign a number, as long as each wire has a different number. Be sure the white neutral wire remains in the wall, untouched during this process.

Step Four: Attach Grounding Wire To Grounding Screw

The grounding screw is likely a green color. The grounding wire should stay attached to the grounded switch throughout the troubleshooting process.

Step Five: Attach The Three Wires To Three Screws, then Test

Attach the three wires to the three screws, once they are safely connected, test the lights. If the issue persists, continue to the next step.

Step Six: Rotate Wires One Position Clockwise, Test Again

Rotate the three wires to the next screw, clockwise. This means the number “1” wire should now be where the number “2” wire was, etc.

Step Seven: Rotate The Wires Clockwise Again, Test One Last Time

Rotate the three wires one more position in the clockwise direction and test again.

Step Eight: If The Problem Persists Wiring Is Not The Issue

If you have tested the wires in all three positions and the issue persists then you have ruled out incorrect wiring. The issue is most likely the switch itself.

Steps To Replacing A Defective Switch

It is highly advised that you replace both 3-way switches simultaneously when dealing with 3-way switches. The reason for this is that if one switch fails, how long will the other switch last? Because they were both placed at the same time, one of them will most certainly fail soon.

Step One: Turn Off The Electricity At The Circuit Breaker

You want to avoid any risk of an electrical shock, especially when messing around with electric components and wires. Turn the breaker off for the switch before you proceed.

If you forget to do this, you’re risking severe electrical shock that can significantly harm, if not kill you. Do not skip this step.

Step Two: Check The Wires

Once you have access to the wires, make sure they are not touching or too close together. You can get confused by the wiring if you don’t have an electrical background. Something you can do before you remove anything takes some masking tape, label each wire, and then take a picture.

Check all of the wires to ensure nothing is touching something that it shouldn’t. If wires are crossed, this could cause your switch to malfunction. Moving them back into their correct place will solve the problem easily.

Step Three: Test For Continuity

This portion necessitates the use of a continuity tester. Check each wire for ground using this tool. Because the ground wire is where the electricity flows, it is often referred to as a “hot” or “live” wire.

There should only be one live wire in a 3-way switch, which is the standard wire. If you detected the live wire on one, there shouldn’t be another live wire on the other switch.

Step Four: Install A New Switch If Needed

Install a new switch and connect it to the terminal path that’s connected to the live wire. The live wire should be connected to the common terminal. Connect the traveler wires to the other two terminals after that. With all the wires inside, close the new switch.

This is where it comes in handy to look at the photo you took of the labeled wires. Put them back as they appear in the picture.

Step Five: Find The Common Wire

By touching one of the continuity tester probes to the wires, you can find the common wire. In one of those wires, there should be a beep. The common wire is the one that beeps or registers a resistance.

Connect the common wire to the common terminal in the same way you did with the first terminal. Connect the other traveler wires to their terminals after that. Now, you’re ready to install the new switch.

Step Six: Install The New Switch And Turn On The Power

With all of the wires inside, mount the new switch on the wall. Check the manufacturers’ instructions to ensure you’re doing it the correct way.

If you’re too overwhelmed by this process, perhaps it’s a better idea to call an electrician. This is a relatively simple job that shouldn’t cost you more than $140 to $165 when hiring a professional.

Additional Troubleshooting Tips For Your Three Way Switch

Troubleshooting a 3-way switch may appear to be a complex undertaking at first. It is preferable to consult a professional if you have no experience with electrical lines and are uncomfortable doing so. DIY may appear to be the most cost-effective option, but if you’re going to rewire it or risk receiving an electrical shock, it’s not worth it.

Another suggestion is to make a notation on the wires. People are prone to overlooking this because spotting a live wire is not difficult. However, you should do this not only now but also in the future when troubleshooting. Even if the other wires aren’t labeled, don’t forget to label the common wire. A simple piece of colored tape will suffice.

When To Fix A 3-way Switch

When should a 3-way switch be troubleshot? A 3-way switch does not require constant troubleshooting. You don’t even have to do this regularly because this isn’t a piece of software that needs upgrading or troubleshooting. Your switches may, however, become malfunctioning at times.

When the switches aren’t working, you’ll most likely need to troubleshoot. Naturally, this assumes that your light bulb is in good working order. If it is, and the switches aren’t turning on or off the lights, you’ll need to troubleshoot. It’s also possible that only one of the switches is broken.

Another example is when the wires are not connected properly. This can cause your 3-way switch to only work when both switches are on. A non-functioning switch can be caused by incorrect wiring, which you won’t know unless you’re an electrician.

Wrapping It Up

3-way switches are meant to be convenient, but sometimes they can cause a headache when they only work in one position. If your 3-way switch only works when both switches are turned on you should first check and test all the wiring. If the wiring is not the issue then you should next troubleshoot the switch itself, as you may need to replace it with a new 3-way switch.

Heather Robbins
Heather Robbins

Heather is a passionate writer who loves anything DIY. Growing up, she learned everything from home repairs to design, and wants to share her tips with you. When she's not writing, she's usually hiking or searching for her next DIY project.

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