The easiest way to test a fuse without a multimeter is to visually check it for damage or burn marks. You can also try swapping the blown fuse with a good one to see if the problems go away. But for more accurate results, using a voltage tester, continuity tester, fuse tester, or bulb is recommended.
Now that the basics are out of the way, let’s have a detailed discussion on how to test a fuse without a multimeter.
How To Test A Fuse Without A Multimeter?
There are nine possible ways you can test if a fuse is working or not. Some methods are very simple, and some are comparatively harder. The nine methods have been described based on their difficulty level, from easy to hard.
However, the best and most accurate way to test a fuse involves using a multimeter.
Method One: Visual Inspection
The first and easiest method of testing a fuse is through visual inspection. If you ever wanted to know how to tell if a fuse is blown without a multimeter or any other tool, here is your answer.
To visually inspect a fuse, you need to follow the below procedure-
- Turn off your car.
- Gain access to the fuse box of your car
- Pull out the suspected fuse with your hand or a fuse puller.
- Look for signs of burns, damage, or crack. If there are dark or gray marks, it’s likely that the fuse is blown.
- Right after blowing, a blown fuse is likely to be warm, whereas a working fuse should feel normal.
- Also, check if the fusing element has melted or not. A melted fusing element indicates the fuse is bad.
With these signs combined with the symptoms of a blown car fuse, you should be able to determine if the fuse is blown or not. This brings up the question, “What are the symptoms of a blown car fuse?”
The most common symptom of blown car fuses is faulty electrical components. Having trouble starting the car or having the engine turn over slowly is another common symptom. Occasionally, your car’s headlights may appear dimmer than usual or flicker on and off.
Although this method is the easiest, it may not be accurate. To make matters worse, you can only use this procedure on certain types of transparent fuses. If you are trying to test a thermal fuse or a ceramic fuse, this method will not work.
So, how to test a ceramic fuse without a multimeter?
To test a ceramic fuse without a multimeter, you can use the same methods as for the glass fuse, except for inspecting it visually. These fuses work essentially the same way. Just because the body is not transparent, ceramic fuses cannot be tested visually.
If you are wondering how to test a thermal fuse without a multimeter, the answer is still the same. All the methods apply except for visual inspection.
Method Two: Swapping With A Good Fuse
You can try swapping the fuse with another one of the same amperage and voltage rating if you are not sure about its functionality after inspecting it.
If the problem persists, the fuse probably was not the issue in the first place. But if the problem goes away, you can assume the fuse was the source of the issue.
Although the application of this method is fairly simple, it might not provide a 100% accurate outcome. That’s because the fault may be in both the electrical system and the fuse. In that case, swapping the fuse won’t be enough.
Method Three: With a Non-Contact Voltage Detector
Testing the fuse with a voltage tester will require you to remove the fuse from its place. But if you use a non-contact voltage detector, you won’t have to remove the fuse.
This type of voltage detector works just like the regular voltage tester, but it does not require placing the tip of the tester on the fuse to get a reading. When it gets close to volts at the other end of the fuse, it lights up or emits a beep.
To use a non-contact voltage detector to test a fuse-
- Gain access to your car’s fuse box.
- Turn your car on.
- Turn the non-contact voltage detector on. In most voltage detectors, there should be a green light indicating that it’s on.
- Get the voltage detector very close to the fuse or even place it at either end of the fuse.
- The light on the voltage detector will change to red or it will beep if there is voltage in the fuse, indicating that it’s working. If there is no change in the light or no sound, the fuse may not be working.
Since it only needs to be near the current in order to beep or illuminate, the non-contact detector cannot entirely be relied upon.
Even when the live circuit isn’t complete, the device could inaccurately recognize voltage from another live circuit.
Method Four: With a Fuse Tester
You need a fuse tester to use this method. This process may be convenient as you can apply this method without removing the fuse.
So, allow me to tell you how to check fuses without removing them, using a fuse tester.
To test a fuse using a fuse tester, connect the tester’s leads to the terminals of the fuse and turn the car on. If the fuse is functional, the tester will not indicate any issues. However, if the fuse is blown, the tester will light up or make a sound, indicating that the fuse needs to be replaced.
However, one disadvantage of using a fuse tester is that it can only be used to test fuses that are the same amperage as the one in the tester.
This means that if you need to test a fuse that doesn’t have the same amperage as the tester, it won’t be able to determine if the fuse is okay. In that case, you will have to use another method to test the fuse.
Method Five: With a Voltage Tester
To test the fuse with a voltage tester, you need to follow the steps mentioned below-
- Get a 9-volt battery.
- Connect the probe of the voltage tester to one terminal of the battery.
- Place the fuse on the other terminal of the battery.
- Now, place the probe of the voltage tester on top of the fuse.
If the fuse is working, the light at the end of the voltage tester will turn on.
Method Six: With a Continuity Tester
You can also test a fuse with a continuity tester. Here is the detailed process for using it-
- Remove the fuse from its location.
- Place the probe of the tester at one end of the fuse.
- Then touch the lead at the other end.
- The tester would indicate either visually by light or by making a sound that the fuse is good.
Method Seven: With a Battery and Some Wires
When current passes through a fuse, it warms the fuse up a bit. You can use this principle to test the fuse, but it might not be accurate.
To test via this method, you will need a battery and a couple of pieces of wire.
Expose the ends of the wires and use the wires to connect the battery terminal to the ends of the fuse. Now keep it that way for a couple of minutes. Then, if you touch the fuse, it should feel warm.
Method Eight: With an Ammeter, Voltmeter, or Ohmmeter
If you don’t have a multimeter but own an ammeter, voltmeter, or ohmmeter, you can use one to test the blown fuse.
For the voltmeter and ohmmeter, you just need to touch the probes to each end of the fuse to get a reading. If there is no reading, then that means the fuse is blown.
Also, if you are using an ohmmeter, any unusually high reading would also indicate a bad fuse. A working fuse should have a resistance of 0 or close to 0.
If you are using an ammeter, you need to connect the fuse to a battery, following the method described in previous methods, and then measure the current. If the amperage is different from the one written behind it, the fuse is good.
Method Nine: With A Light Bulb and A Battery
Light bulbs need a current to turn on, right? Now, if you include a fuse in the circuit, the current will have to go through the fuse. If the fuse is bad, it cannot pass the current to the bulb, and the bulb won’t light up.
Here is the list of tools that you need for this-
- A 9V or 12V LED light bulb
- A couple of pieces of wires
- Wire cutters
- A 9V or 12V battery
Here’s how it works-
- Use a wire cutter to expose about 2 cm of each end of the wires.
- Attach one end of the wire to one of the metal bases of the bulb using rubber tape.
- Attach the other end of the wire to the fuse.
- Connect the other end of the fuse to the positive terminal of the battery.
- Connect the negative terminal of the battery to the other metal base of the bulb.
- If the bulb lights up, the fuse is okay.
- Make sure to use a bulb with low wattages (15-20W) to prevent the fuse from blowing.
However, this method could be dangerous. Without proper caution, you may get electrocuted, as it involves handling live wires. So, we recommend using insulated gloves.
How to Test a Micro3 Fuse Without a Multimeter?
We all know that there are different types of car fuses; among them is a type called the “Micro3” fuse, which has three pins/terminals.
By now, you should have the basic idea of testing a car fuse with two terminals. But how do you test a fuse with three terminals?
The process is similar to testing the fuse with two terminals. All you have to do is test any two terminals at once and then analyze the results.
FAQs
What is the easiest way to check a fuse?
The easiest way to test a fuse is to visually inspect it or swap it. However, to get the most accurate result with the least amount of hassle, using a multimeter would be best.
Can you check fuses without disconnecting the battery?
Yes, it is possible to check fuses without disconnecting the battery. However, it’s best to turn off the car and/or disconnect the battery as a safety measure.
How long do car fuses last?
Fuse manufacturers claim that their fuses can last up to 30-40 years. But in reality, you should consider checking and, if needed, replacing fuses every 10 years.
Conclusion
Knowing how to test a fuse without a multimeter may come in handy when it’s impossible to get your hands on one. Some of these methods are super simple and require no tools. But to get accurate results, it is advised to use tools like a battery or wires.
The most simple one would be the visual inspection method. On the other hand, the most accurate way would be to use a light bulb and a battery.
