Fuses are made to protect critical parts of the electrical system from overheating and other damage caused by them. When there is a flow of electric current that exceeds the danger threshold level, the wire in the fuse will break and close the connection to the electrical circuit it protects. This method can protect the electrical system in your car or home well, but it can also interfere with your comfort when a fuse blows. With the right tools and a little knowledge, you can inspect all existing fuses when this happens and determine if any fuses need replacing.
Step
Part 1 of 4: Locating the Fuse Box
Step 1. Check your car's manual or search for possible places
Most cars have two fuse boxes, and there is no general rule of thumb where they should be placed. You'll save time by first reading your car's manual (or searching online), locating the fuses connected to the car's electrical components that don't work, and then having them checked in person. If you don't have the manual, check the following places to find a large box or set of fuses:
- Most cars have one or two fuse boxes in the engine bay, which are located next to the engine or battery. Some also place a fuse box in the cab, so keep looking if you haven't found one, or if all the fuses you find are still in good working order.
- Late-production cars usually have a fuse box under the dashboard which is easily accessible. Check the roof of the dashboard drawer, for any hinges that can move down. You will probably need a flat-blade screwdriver to unscrew the fuse box.
- Older cars usually place their fuses in an open box to the left of the brake pedal, or parking brake pedal. It can be a little difficult to check the fuse on some car models, so use a flashlight and/or a small mirror.
- There are also those who put it unorthodoxly in the trunk or under the back seat.
Step 2. Locate the fuse box in the house
If you're checking your home's fuses, look for the fuse box or electrical circuit box in a wall cupboard, in the basement, laundry room, or outside the walls of your home. If you live in an apartment or rent together, the fuse box may be in a neighbor's apartment.
Step 3. Check the manual for other equipment
If you want to check the fuse in the air conditioning unit or other equipment, consult the manual to find out where it is. In some appliances, you must first turn off the power before you can reach the fuse box safely.
Part 2 of 4: Checking for Visual Signs
Step 1. Read the label if there is one
Car fuse boxes usually have a diagram on the outside or inside of the lid, as is always the case in the manual. This can save you a lot of time, because you can immediately find out, for example, which fuse protects the connection to the radio (or any other component that is off) instead of checking all the fuses that are more than 40. On the other hand, housing fuse boxes usually don't have a label, but with a number. only a few fuses, of course it's easy to check all of them.
Search for your car's manual or fuse box diagram, online here or using a search engine. You must know the make and model of your car
Step 2. Leave the fuse plugged in
Don't remove the fuse just yet, as this can be dangerous if power is still connected, and can cause minor problems if you find yourself removing a working fuse. Just observe that each fuse is plugged in.
Step 3. Check if the wire is broken or there are signs of burning
A fuse may appear intact but is actually blown (and must be replaced), but there is usually a visible clue that can lead you to whether or not it is blown. Car fuses come in 3 basic shapes:
-
A transparent tube (glass or plastic) with a wire in the middle. If the wire is blown, the fuse is blown. If the entire tube has black or brown soot marks, then the fuse has been blown by a large short circuit in the circuit. This is a sign that something needs to be fixed on the circuit, especially if the replacement fuse you re-plugged blows in a short period of time.
Check Fuses Step 6Bullet1 -
The two-pin fuse usually used in cars, consists of two metal plates connected by a U-shaped wire, inside the plastic. If the wire is blown, then the fuse is blown, but sometimes it takes careful observation to see if the wire is really blown.
Check Fuses Step 6Bullet2 -
Solid cylinder (coated with a layer of solid metal) which must be tested by other means.
Check Fuses Step 6Bullet3
Step 4. Turn off the power and unplug the housing fuse
If you are checking the home fuse, you can turn off the mains power supply to the house and remove the fuse for inspection. For any type of fuse, if you're still not sure if it's working or blown, move on to the next section. If you have managed to determine which fuse is blown, skip the following steps and please go directly to the step of replacing the fuse.
This step is not recommended when checking car fuses, as removing the wrong fuse may affect engine rev performance, diagnostic information or car accessories
Part 3 of 4: Checking the Electrical Circuit
Using Pen Test
Step 1. Purchase a modern test pen
You can buy this tool at a hardware store or electrical store. Choose a "computer safe" model with an LED light on the handle, or one that has its own incandescent light source or battery. Never check a car's electrical circuit with an older test pen that draws power from the circuit itself, otherwise you don't want to trigger the airbag and cause serious damage.
Alternatively, if you have a multimeter, use it and skip straight to the steps to use it
Step 2. Check the fuse using a test pen
Follow these steps to check the fuse with a test pen:
- Clamp the ground rod on an object that can conduct electricity (such as a metal object).
- Start the engine, or if you are testing a house fuse, make sure the power is on.
- Touch the red wire to one end of the fuse, then touch the other end. For a bipedal fuse, the ends are the two legs.
Step 3. Interpret the results
If the fuse is still functioning properly, the light on the test pen will flash once for each end. If it does not light when touched to one end, then the fuse is blown and needs to be replaced.
If the light does not come on at all when the test pen leads touch either end, then no current is flowing to the fuse box, or the ground rod has not been connected, or the light on the test pen is blown. Fix this problem first and try again, or just use a multimeter
Using Multimeter
Step 1. Turn off the power and remove the fuse
Turn the ignition of the car to the off position, or turn off the electric power that flows to the home fuse box. Unplug and remove the fuse, starting at one end then the other. You may need tweezers or mini pliers to remove the fuse, or use a similar tool provided, which is sometimes tucked into the lid of a car fuse box.
If you plan to test more than one fuse in your car's fuse box, take a photo of the initial condition so you don't get confused when it comes to reinserting each fuse
Step 2. Perform a continuity test if possible
Most digital multimeters have a continuity setting, which is listed on the label as a series of parallel arcs:))). Turn the knob to this setting, then connect the two multimeter wires to each end of the fuse. If you hear a constant beep when the wires are connected, then the fuse is still in good working order. If you don't hear any sound, the fuse is blown.
If your multimeter has no settings for the continuity test, or you still want to test again in a different way, proceed to the resistance test
Step 3. Set the multimeter for resistance test
These settings are marked with the Greek letter "Omega": ️. The resistance test setting will run a small current through the fuse, and record how much current is passed. We do not need to know the details of this resistance measurement, but what is clear is that if the fuse is blown, we will not get any results on the multimeter because the current that flows cannot pass through the broken wire in the fuse.
If you have an analog multimeter, there are many settings for. Choose the one that says x1. Older model multimeters sometimes write it as Rx1
Step 4. Touch both ends of the multimeter wire
Touch the two ends of the multimeter cable to each other, and look at the numbers that appear on the screen. This number (or the number indicated by the needle on an analog multimeter) is the number that the multimeter considers to have a resistance of 0. If when you test the fuse, you get a similar number, then the fuse is still good.
Your multimeter may have a knob (on analog multimeters) or buttons (on digital multimeters) to return the above number back to 0. Use if you plan to use the multimeter frequently, but it is not essential for this test
Step 5. Touch the two ends of the wires to each end of the fuse
Touch both ends of the multimeter wire to each end of the fuse, while observing the screen. If the numbers on the screen don't change when you touch them, then the fuse is off and needs to be replaced. If the number changes or the needle moves closer to the value you obtained from the previous step, the fuse is still good and can be used again. Put it back on the fuse box.
Part 4 of 4: Replacing the Fuse
Step 1. Turn off the power and remove the fuse
When you remove the old fuse and install a new one, make sure that the power flowing to the fuse box is turned off. In cars, this means turning the ignition key to the off position.
Step 2. Prepare a new fuse
You can buy it at a hardware store, electrical store, or auto parts store (only for car fuses). Bring a blown fuse with you when buying a new fuse, so you can compare the sizes and characteristics listed below.
Step 3. Select a new fuse with the same current rating (Amperes), type and shape
It is very important to replace the fuse with the exact same type. Most importantly, check the current rating, which is usually written on the body of the fuse, and buy a replacement fuse with the same rating. Each fuse is designed to blow after passing a certain threshold according to its current rating, and this is exactly what it does. If you replace it with a fuse of a lower current rating, the fuse will blow frequently in normal use and may cause a short circuit. If you replace it with a higher current rating, the fuse won't blow when there's an overcurrent, so it's another component that should be protected that isn't necessarily replaceable.
Transparent cylindrical fuses are of two types: direct blowing (with straight wire) or indirect blowing (with threaded wire). Do not replace a fuse with a direct blown type, unless the original fuse was like that. Otherwise, the fuse will not blow quickly enough to prevent further damage
Step 4. Install a new fuse
Modern fuses should be easy to install with minimal pressure. Older glass fuses sometimes have to be installed by inserting one end first, then the other.
Tips
- As with any other object, fuses will also age. As time goes by, it will definitely break up. Therefore, a blown fuse does not always indicate that there is something wrong with the electrical circuit.
- If a blown fuse in a car causes your car to stop moving, even though you had to use the car to buy a new one, check your manual and then remove a fuse of the same current rating from a non-essential electrical system (e.g. radio), for temporary installation. replace the blown fuse.
- If the replacement fuse also blows within a short time after installation, and you believe you are using the exact same current rating, there may be a more serious problem with your electrical system. Please contact an electrician.
