All vehicle’s electronics are powered by the electricity that is generated by the alternator that converts the mechanical power produced by the engine into electrical power.
That is why all cars must have fuses, an electrical safety device that protects the electrical circuit in which it is installed and melts in case it receives too much heat in order to interrupt the current.
A blown car fuse is the most common reason why the car’s electrical parts stop working, so if your radio or speakers suddenly stop functioning the first thing you need to check are the fuses.
So, in this article, we are going to show you why and how to tell if a car fuse is blown and show you how to replace it.
A blown fuse indicates that there is a short circuit that can be caused by the contact between two wires or the contact between a power wire and the vehicle’s body.
A car part that draws a higher current than it is designed for can also cause a fuse to blow, so a jammed wiper motor can easily pop a fuse.
Any metal object, like a coin that comes into contact with accessory power socket, will cause the fuse to blow, as well as a lightbulb that isn’t compatible with the tail lights or headlights.
Ideally, you should identify the reason why the fuse has blown before you replace it in order to make sure that the issue cannot cause more damage to your vehicle.
The car’s electronic system powers different parts of your car and it is commonly divided into the following categories:
If a car part from any of these categories isn’t working, you should check the fuses in the fuse box that protect the vehicle’s circuits. It is worth noting that seeking assistance from a professional is advised in case a car’s engine control unit or transmission control aren’t functioning properly.
However, if the car’s tail lights or its sound system aren’t working, then you can probably change a blown fuse on your own. Most car manuals contain a fuse map that will help you locate the fuse boxes in your car.
The fuses located in the so-called cigarette lighter socket or the accessory power socket are the most prone to melting, as car owners often forget to unplug their phone chargers or because a coin makes contact with an exposed power outlet.
Keep in mind that even the simplest car models have over thirty electronic controlled units, while luxury cars can have up to one hundred electronic control units.
The information regarding which car part is protected by a particular fuse is located within the fuse box, which enables you to easily locate the fuse that is associated with the malfunctioning car part.
The vast majority of cars and vans have two fuse boxes, but some vehicles can have up to four fuse boxes, and you should check the user manual in order to find out their exact location.
The most common fuse box locations are:
What’s more, all cars have at least one fusible link or the main fuse that is commonly installed at the positive battery terminal or in the fuse box that is attached to the battery positive cable.
Additionally, some car models can have more than one fuse box under the hood, and you must make sure that the blown fuse is located within the fuse box you’re inspecting.
Most dashboards are located in the vehicle’s footwell area, although on some car models the fuse box can be placed in the panel on the side of the dashboard that can be accessed after you open the door. Click here if you are searching for a floor mat.
Ultimately, the positioning of the fuse boxes depends on the car manufacturer and a particular car model, which is the reason why you should consult the user manual if you are not sure where exactly the fuse boxes are located in your car.
Once you’ve traced the fuse box that houses the fuse you suspect to be blown, you should open it. The vast majority of fuse boxes have a diagram that shows you the position and the name of each fuse so that you can easily find the one that is associated with the car part that isn’t working.
For instance, your car won’t have power or the interior lights after the main fuse has blown. It is not uncommon that a few other fuses blow together with the main fuse, so you must check if all other fuses in the fuse box are still operational.
Proceed to inspect the blown fuse visually, since most commonly a blown fuse is going to be melted. The metal wire within the fuse is going to be broken if the fuse is blown.
In case the fuse box doesn’t contain a diagram that shows you what a specific fuse does, you can use a test light to locate a blown fuse.
Simply switch on the ignition, and use the test light’s probe to touch each end of a fuse. Follow this link if you would like to learn how to use a test light. Optionally you can check out our review of the best OBD2 scanners that enable you to figure out what is wrong with your car without having to visit a mechanic.
Even though you can remove a fuse by hand it is still better to use proper equipment in order to avoid making unnecessary damage to the fuse box.
You are going to need a multimeter in order to check if the fuse is blown, and there are two ways to complete this task.
Prior to taking out the fuse, you should measure its voltage at both pins of the fuse. These pins stick out of the upper part of small car fuses, which enables you to measure their voltage without having to pull them out by hand or with pliers.
Ensure that the multimeter is set to Direct Current (DC) and then proceed to attach the COM terminal to a negative battery terminal or any of the metal parts on the car’s body or chassis. Switch on the ignition and use the positive probe to measure the fuse’s voltage.
The measurement should show 12V on both sides of the fuse, but if the measurement shows this value on just one side that indicates that the fuse is blown.
Alternatively, you can use the multimeter to measure the fuse’s resistance, but you must first remove it from the fuse box. Simply change the multimeter’s settings to Ohm, and place its probes on both sides of the fuse. A functioning fuse will have the resistance that is close to zero or zero, while a high resistance value that is close to infinity indicates that the fuse is blown.
Once you’ve detected a blown fuse, you should search for a new one online or head over to the hardware store and purchase the exact same fuse like the one that you’ve taken out of the fuse box. There are three types of car fuses:
Don’t attempt to replace one type of fuse with another one or insert a 10V fuse instead of 12V fuse into the fuse box, because by doing so you may cause serious damage to your vehicle. When you have a new fuse simply insert it to the fuse box in place of the old one and switch on the ignition in order to check if the car part connected with the fuse is now working.
Detecting and changing a blown fuse can save you a trip to the mechanic, but if the same issue persists you shouldn’t hesitate to contact a professional. Moreover, it is sometimes necessary to replace the entire fuse box and not just a single blown fuse.
You shouldn’t attempt to change the fuse box by yourself unless you have the necessary knowledge and skills to do so.
Automotive fuses are a particular type of fuse that safeguards a car’s electrical equipment and wiring. They are commonly rated for circuits that don’t exceed 32 volts of direct current.
Even though it is impossible to eliminate all chances of a fuse popping, performing regular checks of your vehicle’s electronic system will significantly reduce the chances of a fuse blowing.
Different types of car fuses can be purchased online, and a simple web search will enable you to find a replacement for a blown fuse within minutes.
You can purchase a car fuse for $10 to $20 depending on the model, although specialty fuses can cost up to $100.
Detecting and changing a blown fuse is a simple process, although you are going to need access to some basic tools.
Visually inspecting a fuse is by far the easiest way to determine if a fuse is still functional because a short circuit will melt a fuse in most cases.
Measuring the fuse’s voltage is recommended in situations when it is not easy to ascertain if the fuse is damaged or not.
