3-way switches are commonly known for their confusing wiring instructions among average homeowners who wish to install these themselves.

Therefore, it is important to know how to test a 3-way switch. To make sure that they made the installation properly.

The first step is to check the other components of the circuit, such as the light bulb and the breaker. If they pass the test, turn off the power and open up the switch, recheck the wiring, and replace the switch if necessary.

The step-by-step guide to testing and troubleshooting a 3-way switch will be provided throughout this article.

What Is a 3-Way Switch?

A 3-way switch can operate two different circuits with only one switch. They can also be used to operate a light switch from two different places. But it needs to be wired differently in such a case.

Fig 1- Diagram of a 3-Way Switch
Fig 1- Diagram of a 3-Way Switch

A 3-way switch has 3 terminals that you can see from the above diagram (Fig 1). Terminal 1 is the power supply. It can either make the power flow through terminal 2 or terminal 3.

They are usually wired in such a manner to operate a single light from two different locations. Such as from the top and bottom of a staircase. Or the beginning and end of a long corridor.

It requires special wiring instructions to be followed. Though it might be a bit complex at the first glance, if the instructions are followed properly, it isn’t that hard.

Common Problems with 3-Way Switches

Like most switches, 3-way switches are also prone to several problems and issues. Some of the most common problems are as follows.

Loose Wiring:

If the wiring was not made properly secure during the installation, it can easily get disconnected from the terminals and prevent it from working.

If a 3 way switch only works when one switch is on, it could either be due to loose wiring or faulty wiring.

Improper Installation:

One of the most frequent issues homeowners have when installing or replacing their 3-way switches is improper wiring.  As stated earlier, the wiring procedure may be a bit complex for people not familiar with such tasks.

When replacing a 3-way switch at home, it is quite simple to accidentally attach the wires to the wrong terminals. Therefore, a wrongly installed 3-way switch may also be the reason behind its malfunction.

Damaged Switch:

It is possible for the switch to either be faulty or get damaged over time due to wear and tear.

In such a case, it is a must to get the switch replaced with a new one.

Tripped Breaker/Broken Light Bulb:

Then again, the issue might not be with the switch at all.

Make sure the bulb is not burned out and the breaker supplying power to the 3-way switch has not been tripped. Test the light switches after making sure the breaker that feeds the switch is in the “on” position.

How to Test A 3-Way Switch?

There are several steps you have to follow to properly test a 3-way switch. As well as to know how to troubleshoot 3-way switches. The steps are as follows.

Preliminary Diagnosis:

  1. Before messing with the switch, check whether the breaker is tripped or not. Reset it if tripped.
  2. Also, make sure that the light bulb or appliance you are trying to run is working properly by plugging it into another outlet.
  3. If the light bulb or appliance is working fine, it’s time to test the switch itself.

Steps to Test the Switch:

Fig 2- Using a Multimeter to Test a 3-Way Switch
Fig 2- Using a Multimeter to Test a 3-Way Switch
  1. Turn off the power from the main panel.
  2. Test if the power has stopped flowing using a voltage tester at the switch.
  3. How to test 3-way switch with multimeter? First, put the multimeter in continuity mode.
  4. Measure for voltage at each of the switch terminals.
  5. Turn one switch On and then Off while measuring.
  6. Turn the other switch On and then Off while measuring.
  7. If there is a presence of voltage at either position, your switches are working properly.
  8. If not, one or both of the 3-way switches requires troubleshooting.

Steps to Troubleshoot the Switch:

  1. Determine whether the switch needs to be rewired or replaced.
  2. Both of these would require you to know how to wire a 3-way switch.
  3. Check whether the switch is wired properly.
  4. If not, simply rewire the circuit and the 3-way switch.
  5. But if it needs to be replaced, you have to properly follow the steps to install a 3-way switch.


I hope that now you have enough knowledge about how to test a 3-way switch. This article also states how you can troubleshoot one.

But electrical endeavors don’t always go as smoothly as planned. Therefore, if you cannot seem to figure out the problem, feel free to consult a professional.

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