How To Fix Christmas Lights With A Multimeter

We might use Christmas LED lights very often. Not only at Christmas time, during birthday parties, fairy lights festivals, we always use these lights to fantasise about our evenings. But if these lights are not working on the occasions, that kills the festive mood. It is the most common problem to face. Luckily we can fix it with a bit of DIY fixing, with the help of a digital multimeter.

What Happened if Christmas Lights are not Working

With the help of a multimeter, we can quickly fix the Christmas lights. We need an electrical digital multimeter. In the multimeter, you require to set the dial meter on the Ohms setting. So that it has a beep to it, when we put one lead of the multimeter into the bulb inlet, the multimeter will give you a beep. Whenever it touches or contact with itself, it will always have a beep. So we are going to set that aside because all we are looking for is the known beep. We are simulating this because this light strand is working now. But if we get a beep, that means that the wire from one end of a single bulb is a good plugin.

How do we know only a bulb is not working

A light that will probably not light up for you, move on to the next bulb, then unplug it as long as you have 0 ohms or close to 0 ohms. It is going to beep. Plugin the next bulb now. If you get to the point where you take the bulb out, and insert the multimeter lead into the bulb inlet, if you do not get a beep like that, then that means the bulb is bad and to replace that bulb with a known good bulb which is a good shunt.

How to check if a bulb lit dimly

We would have a suitable filament and a good shunt now we have tons of bulbs sitting on the table right there, all of them have good shunts to them. They will work; they do not light up, but they have good shunts, so they will make the whole strand light up still. We will put one in for you.  You may see they have good shunts. They will make the strand light up, but they would not light up themselves; put in a good shunt– that is a bad filament in the bulb, but the shunt is still intact, which allows voltage to go through to each part of the strand.

How To Fix Christmas Lights With A Multimeter

To check the Whole Strand, do the Continuity Test

If we even take that bulb out, we still get an Ohm reading and a continuity test to make the strand work. So the worst part about this whole diagnosis process on these lights, no matter what, you have to start at the plug, and you have your test lead into the wire that runs the length of the whole strand, and that will be continuity with the one three wired light at the end of the strand. If you have continuity in testing, they are never going to be any broken wires. So yes! that first light on this strand goes from two wires to three wires. If at any point in time you are going down the chain and you do not get a beep, that means the bulb before it is bad and is not sending the signal through; as of right now, filaments are burned out, but the shunt is still good so that way it still carries through the strand.

Steps to Fix the Christmas Lights problem

1. Check the Outlet, if it it is working well.
2. Check the string wire, that it is not torn or damaged. It can be a severe problem. It can give you a current shock or a short circuit.
3. When you start diagnosing, you have to start at the end from the plug, and you got to go down the line one at a time. So, therefore, this will save so much time because you can be putting in bulbs with a bad filament and a bad shine; you expect it to light up.
4. Make it light up that is not the case. It does not have to be an excellent bulb to send power and route power through the rest of the strand, and ninety per cent of the time, it will not end up being the one that is almost closest to the end of the half strand. So we have got about, we guess, let’s say out of 50bulbs, which is half the strand.
5. Final step is the Continuity test. We have got about 30 to 35 is beeping. The rest, which is not beeping, then replace the bulb—beeping, beeping, not beeping, replace the bulb until we get beeping beyond each side. If we get no beeping here, then we have to replace that bulb. If we get beeping, we just pull that one out, put it there, and check that one for continuity. If it beeps, we can move down the line repeatedly until we get to the centre portion of the strand because half of the strand will light up sometimes, better than 50 but the last half of this strand.

Frequently Asked Questions

What Christmas Lights should I buy?

Commercial LED light strings are the most popular commercial Christmas lights among professional buyers due to their exceptional durability.

Why do LED Christmas lights burn out?

If one of the lights is not working in your LED light strands, it is probably because it has a bad bulb. If one bulb dies, it can cause the rest of the strand to stop working. The only way to fix the problem is to find the bad bulb and change the bulb.


In this article, we have discussed how to test the Christmas lights with the help of a multimeter. If we buy a string of lights, we explain stepwise what to check first. First of all, check the plugin outlet whether the outlet worked perfectly; you can check this with the help of a tester to check the power. Next, check the wire string; if it is broken or torn, tape it to avoid any hazards. Then, when every connection is proper, check the bulbs one by one if some are working and some are fused. Finally, check the bulb inlets with the help of a multimeter, one by one till the end, to check the continuity of the strand. On the other hand, we will review the non-function Christmas lights or check when half the string is out in our next article.

Read more:

How to Use a Multimeter

How To Test Electrical Wires With A Multimeter

How To Check 240 Voltage With A Multimeter