There are many reasons your car may not be starting, but one of the most common is a blown fuse. You can learn how to check car fuses with a multimeter in this blog post.
Blown fuses will cause either no power or interrupted power to electrical systems. Your headlights, horns, dash lights, windows, or car locking may fail due to just a blown fuse. If there is a problem with the alternator, then you must contact your automotive technician. However, please continue reading this guide if you believe that a blown fuse may cause the issue.
Why should I know about fuse testing?
Fuses require testing, therefore knowing how to test a fuse with a multimeter is essential. Because it helps you figure out what the problem is with your car's electrical wiring right now. If you have a multimeter for home use, it is easy to check your car's fuses in a few minutes. If you don't, you can ask someone who has a multimeter to check them for you. For more information on checking car fuses, please refer to your owner's manual or help section of your car's software.
Using techniques such as "jumping" or "shorting" the fuse will allow current to flow through the fuse. But it is not recommended and can cause damage to a car's electrical wiring. Read how to test Christmas lights with a multimeter.
What does it mean by blown fuse?
A blown fuse means that either there is too much current running through it or not enough. But this is only temporary, and eventually, the circuit will pop open due to high current flow. If one of your fuses keeps blowing out, don't hesitate to contact an automotive technician.
Because the problem may be with your electrical system, not with your car fuses. If your multimeter reads any shorted accessory then immediately switch of ignition to cut off the power runs through circuit of that accessory.
What is a fuse?
"A fuse is a safety device that protects the wiring circuits in your car's electrical system." A blown fuse means that there is either too much current running through it or not enough. Before knowing about how to test a car fuse, you must know about types of fuses.
Types of fuses
Blade fuses: These are the most common type of fuses. You can check if your multimeter has a continuity or buzzer function. To check them, touch both fuse terminals with test leads and listen to a beep. If there is no sound, then it means that both terminals do not have continuity. It means your fuse is blown or weak. If you hear a beep, then that means that your multimeter found continuity between the two terminals indicating fuse good condition.
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Most cars have these bigger fuses. you can easily test them by placing read lead at one end and black lead at another end. After this select the continuity setting option or low resistance mode. If the resistance is below 10 ohms or multimeter beeps on continuity setting then it's ok. But if it shows an open loop then you must have to replace the fuse.
Cartridge fuses: These are harder to test because they usually require a digital multimeter. If you have a multimeter, then you don't have to worry about how to check car fuse with a multimeter. Instead, you can check them in the same way as blade fuses. First, touch one lead to each terminal and listen for a tone to indicate bad or good.
Mini fuses (small fuses): These are the smallest type of fuse, and it is harder to tell if they are blown because they sometimes look fine even when they aren't. There is a way to test them, though, but it requires a digital multimeter, as stated before. First, touch one lead to the positive terminal and then use your other lead to connect each side of the fuse until you hear a tone indicating continuity through the fuse. If you do not hear anything suspect the fuse is bad.
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How do I check the fuses in my car?
You will need to locate and pop open your fuse box or pull out your circuit breakers and look at each fuse. Because there are several different styles of fuse boxes, we cannot give you specific instructions for checking them all. However, here is a list of the most common fuses and their locations.
Things you need for checking car fuses
- Multimeter or battery tester
- Metal screwdriver or any metal object to touch the ground terminal
- New fuses
- Jumper links or small insulated wire pieces
How to check car fuses with a multimeter? Step by Step Guide
- Place your multimeter into electrical resistance mode. if you have an auto ranging multimeter then no ok otherwise set the initial or the "V-Ohm-Amp" scale.
- Turn off and unplug your car.
- Make sure that your probes are touching the terminals of the fuse you want to check.
- If you see 0.00 ohms or listen to a beep sound, then the fuse is good.
- If you see a number greater than 30 ohms, the fuse is blown or weak and needs to be replaced.
- Move onto another terminal in a clockwise direction and test the next fuse in your car.
- Repeat these steps again and again till you find the faulty fuse.
- After finding the blown fuse, just replace it with a new one. If you see any Overloaded/Burnt wire then you can replace it with new one.
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How to check fuses without removing them?
- Inspect the fuse box: Locate the fuse box in your vehicle or the relevant area in your home or office. Familiarize yourself with its layout and fuse assignments.
- Turn off the power: If you're dealing with electrical fuses, make sure to turn off the power to the circuit you're inspecting. This is crucial for your safety.
- Visual inspection: Examine the fuses for any visible signs of damage, such as a broken filament or a discolored glass casing. Look for signs of burnt marks or a melted appearance.
- Fuse tester tool: Obtain a fuse tester tool, which is specifically designed for checking fuses without removing them. These tools are available at automotive stores or online.
- Insert the tester: Insert the probe of the fuse tester tool into the small opening or test point on top of the fuse. Ensure a secure connection between the probe and the fuse.
- Read the tester: Look at the indicator on the fuse tester. It may have an LED light or a digital display. Pay attention to the reading or indication provided by the tool.
- Check for continuity: The fuse tester will determine if the fuse has continuity, meaning the electrical current can flow through it. A positive reading indicates a functioning fuse.
- Replace faulty fuses: If the tester indicates a blown fuse or a lack of continuity, you need to replace the faulty fuse with a new one of the correct rating. Refer to the fuse box diagram for guidance.
- Re-test (optional): If you have replaced a fuse, you may want to re-test it using the fuse tester to ensure it's working properly before closing the fuse box.
- Restore power: Once you have finished checking and replacing fuses, restore the power to the circuit by flipping the corresponding switch or breaker to the "ON" position.
How to check car fuses with a battery tester?
- Turn on your battery tester and touch the positive probe to one end of the fuse and Negative probe to the other end.
- If one or more segments light up, then that means that your fuse is good
- Repeat the process for each fuse in your car's electrical system.
Helpful tips and safety precautions when checking your car's fuses with a multimeter
Before checking your car's fuses, ensure that you have turned off all lights and electrical devices such as the heated seats, windows, music system, and any other power-consuming device to prevent damage.
- Don't touch anything else but the fuse you check. Because touching other metal parts may cause sparks and short circuits.
- Make sure that you are wearing shoes before checking your car's battery.
- Keep flammable objects away from where you are working because checking your car fuses create sparks and heat.
- If you are not sure how to check your car fuses, ask someone who knows or contact a local mechanic.
- Do not hold down any "fusible link" because this may cause damage to your car's electrical system.
- Using the wrong fuse type may cause damage to your car's electrical system.
- Replace all old fuses with new ones of the same size and color code, if available. If you do not have the suitable types of fuses for your vehicle's electrical system, then use jumper links or small pieces of wire instead. However, it's not recommended to replace fuses without knowing. But it's better to do something rather than sit idle. Before doing this, you must check for any short circuit, which can be easily done by checking the multimeter reading.
How do I locate the fuse box in my vehicle?
You will need to locate and pop open your car fuse box or pull out your circuit breakers and look at each fuse. Because there are several different styles of fuse boxes, we cannot give you specific instructions for checking them all. However, here is a list of the most common fuse box locations.
Common locations of car fuses
- Cigarette lighter socket /accessory fuse (usually 10 amps) – located in the cigarette lighter
- Instrument panel fuse, battery saver relay, powertrain control module (PCM), or computer fuse (usually 15 amps) - usually found behind the dash on the driver's side
- Heated mirror fuse (usually 10 amps) – located in the power distribution box, which is underneath your hood
- Central lock/unlock relay (20 amps) – located in the driver's side door or steering column
- Power door locks (15 amps) – located in the driver's side door or steering column.
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After reading this, you might clearly understand how to check car fuses with a multimeter and battery tester. It is a great idea to do it yourself, but get in touch with me if that sounds too complicated for you! I can help you assess the situation of your vehicle's electrical system. So, you know what needs fixing before anything else goes wrong.
Broken wires in your car can also be damaged. So always check brake lights, wiring harness, and other electrical components in your particular system. I have also made a list of the best multimeters for automotive. Let me know about your experience checking out these tips. Then, you can grab the best automotive multimeter for yourself and let me know about it.
Frequently Asked Questions- FAQs
What happens if I replace a blown car fuse with a higher-rated fuse?
If you replace your blown fuse with a higher-rated one, then it could lead to an electrical meltdown and severe damage to your car. If there is not enough power going through it, then nothing will happen. Most of the time, it will work. But if the new fuse continues popping after replacing it multiple times, you should contact your auto electrician.
What happens if I replace a blown car fuse with a lower-rated fuse?
If you replace your blown fuse with a lower-rated one, it will not provide enough power to the electrical components. As a result, electrical components will shut down or start blinking until enough power goes through them. If this problem continues, then bring your car into an automotive technician or auto electrician garage.