Automotive fuses are installed by manufacturers to protect the wiring and devices in your car from electrical overload.
Overloads can happen when an electrical circuit has a short to ground or internal problem that causes the device to draw too much electricity from your battery.
If this was to occur the fuses which is placed between the battery and the device would melt and turn off the flow of electricity before damage could occur.
Where are my fuses?
Automotive fuses are usually found under the drivers side dashboard. A compartment cover may need to be removed or they fuse box may be mounted on the firewall between the engine and the dashboard out of sight but readily accessible for maintenance.
Many models of cars will split the fuse box location between the normal location near the driver and a remote location under the hood. If you have two fuse boxes then the fuses that are found under your hood will normally protect the circuits needed to run your engines electrical system and the ones found in the drivers compartment will protect circuits for your headlights, radio, blower motor and other devices.
A third place you can find automotive fuses would be inline fuses used when accessories are installed. You will commonly find an inline fuse installed on car radios. This type of fuse is barrel shaped and different then your average automotive fuse.
Finally you may have a Main Fuse which is a 1×1 inch box located near your drivers firewall fuse box that protects the electric fuel pump and a portion of your starting circuit.
These four locations are the most common places you can find fuses in your cars electrical system however whenever a third party device is added a fuse may be used.
How to check your fuses
Inline fuses Buss Fuses are probably the easiest to check although your car will not have a number of them to check the fuse you simply unscrew the connector holding the fuse and inspect the fuse wire for a break. If the glass is broken or cloudy that indicates a bad fuse. You can check with a Ohm Meter but replacement is probably necessary.
The amp rating of the fuse will be located on the glass or metal part of the fuse and you will use that number to purchase a replacement. Along with the Amp rating of the fuse you may find that the length of the fuse can vary. Most inline fuses use a spring loaded connector so a slight length difference may still work if the connection is tight.
Blade Fuses
Blade fuses are the most common automotive fuse and they are found in fuse blocks.
To check the fuse you are suppose be able to look at the end of the fuse without removing it from the fuse block and look for a break in the wire inside it. For some reason this is almost never possible in the real world because of low light conditions or the angle that the fuse block is mounted.
Most fuse blocks will have a number next to the fuse and a small chart telling of the circuit it protects. Often this chart is on the back of a cover plate or on the firewall.
If you can try to match the circuit you are having problems with with the correct number fuse and remove it with your fingers. If the fuse is difficult to get out you can sometimes use a screwdriver to pry it out or needle nose pliers. Replacement fuse sets with an assortment of fuses often include a puller. If you have such a tool then use that.
Visually inspect the fuse for a break in the loop of flat wire that connects the poles of the fuse. If necessary hold it up to the light.
Fuse testers are also available to test buss fuses while in the fuse block. They require a small watch sized battery to operate so if you have one thats great but don’t depend on it if it has been sitting in your tool box for 5 years just waiting for its day to be used.
If the fuse is bad you will need to replace it.
Replacing the fuse
Blade Fuses come in 2 sizes Normal and Mini and they come in a variety of Amp Ratings.
Buss barrel shaped fuses as we said before can come in a variety of lengths and amperage ratings so you will need to match both the size and amp rating.
You must always use the same amp rated fuse in your fuse block to protect your circuits.
Although the fuses are suppose to be color coded to allow quick identification ALWAYS READ THE NUMBER of amps that is labeled on the fuse.
If the fuse immediately blows out again when you try to operate the devices that are on that circuit.you know you have a serious problem that needs to be examined.
Inspect your wiring and devices then make repairs before you replace the fuse again.