Fuses protect your vehicle from dangerous situations that could result in shocks, burnt circuits, or even fires. There are many types of fuses including glass tube fuses, blade fuses, fusible links, and others.
For this article we will focus on blade type fuses as these are most common in modern cars. Blade type fuses come in these main types:
Maxi Fuses - these are the largest fuses and are used in heavy duty or higher amperage situations. In many cars you will see one or two maxi fuses as main fuses, then smaller ATC or mini fuses for the individual circuits.
ATC/ATO Fuses - These are the first type of blade fuses and were patented by Littelfuse in the 1970s. They are found in a large amount of cars and trucks made in the 80s and later.
Mini Fuses - Smaller in size than ATC fuses, these fit into tight applications. They cover most of the same amperages as ATC fuses.
Micro Fuses - Even smaller sized than Minis, they also are available in smaller amperages.
With any of the blade fuses it is possible to replace one fuse with any other amperage fuse. This sure is tempting if you have a fuse that has blown multiple times, but this can be dangerous. Fuses are designated for that size circuit. A blowing fuse is an indicator of an issue in that circuit. Check for shorts, faulty accessories (fan motors that are ending their lifespan often cause this), or 'additions' to the circuit that are now placing too high of a demand on it.
Fuse Color Coding:
Blade fuses are color coded by amperage rating. This makes it easy to match up a replacement fuse. Here is a chart of the different colors and amperages available by fuse type:
Indicator or "Smart Glow" Fuses:
Fuse blocks are often located in pretty inconvient places. If you suspect you have a blown fuse, it can be challenging to find the culprit. Pulling and inspecting them may lead you to the right one, but sometimes it can be tough to visually identify a blown fuse. Indicator fuses, often listed under the brand name 'Smart Glow' solve this problem. When they blow, they actually light a small LED in the fuse body. Simply replace the one that is lit up and you can be on your way.