If you’ve ever had an electrical system in a vehicle stop working altogether, you know how frustrating it can be. Maybe your power windows quit when you’re trying to place an order at the drive-thru, or your A/C stopped on the hottest summer day possible. Whatever the problem, getting it working again is of the utmost concern.
Where do you start? Whether you’re a complete newbie or an experienced mechanic, checking the related fuses and replacing a burnt or blown fuse is the first step.
Why a fuse doesn’t work anymore
For a car’s electrical system, a very precise amount of current is required in each circuit. Too much power can cause a component to short out while too little power will mean it doesn’t function, or it functions poorly.
Fuses regulate the amount of power that funnels through a circuit, and by design it’s intended to be the weak spot. If a circuit experiences a short to ground or the component draws too much power, the fuse will blow.
However, a fuse can fail for other reasons too. Corrosion on the terminals or blades, or a simple break in the element from jarring or impact, can cause an open circuit—that is, a fuse that doesn’t close the power connection to the component. When that happens, the fuse needs to be replaced.
How to change a fuse in a car
In a car, different styles of fuses can exist. Across brands and models and spanning different years, there could be different styles of fuses in use. Here are the common ones you might encounter, and how you can go about changing them.
Changing a blade-type ATO fuse
By far the most common type of fuse that’s used in the automotive industry is a blade-style fuse. They’re designated as ATO fuses and come in a variety of sizes. They’re color coded according to their voltage rating.
Blade-style fuses are extremely simple to change once you’ve identified which one has failed. Most fuse boxes contain a plastic puller that fits around the plastic fuse body. Place the puller over the fuse, pinch it tight, and pull the fuse out. Then, install the new fuse simply by lining up the prongs and pushing it in place. If your puller is missing, you can also use a shielded pair of needle-nose pliers.
Changing a Maxi fuse
A Maxi fuse often looks like a large blade-style fuse and works in very much the same way. The one thing to be careful with on a Maxi fuse is that it could be secured in place with a screw. If there’s resistance when trying to remove the fuse, check for a screw that needs to be loosened first.
Changing an AGU auto fuse
AGU fuses are common in vintage or classic cars up through the 80s. It’s a glass tube with a metal contact on either end, and an element running between the contacts inside the tube. Removal is extremely basic—pull directly up on the fuse with your fingers, being careful not to break the glass. Push the new fuse into place until the springy end contacts hold it tight.
Replacing a Mega fuse
A Mega auto fuse is found in some foreign makes and models and is a higher-rated fuse for systems with more electrical draw. These fuses are bolted or screwed into place. Once you locate the fuse, loosen or remove the screws, remove the burnt fuse, and install the new one. Tighten the screws.