Why Cars Have Fuses: What a Fuse Does & How They Work • Cars Simplified

Although fuses serve a very simple function, it is often a misunderstood part and that could lead to improper fuse replacement in more than one way. Steve explains fuses with a simple electrical diagram, showing different scenarios.
The type of fuse shown in most of this video is a maxi fuse, a rather large fuse that you are unlikely to find on a modern car, but the concepts are still the same! The size of fuses have decreased over the years so that they take up less space and more can be used.
• What is a fuse? A fuse is an electronic protection device designed to fail in the event of a problem, so the expensive and more difficult to replace parts are not damaged.
• How does a fuse work? A small piece of conductive metal is designed to handle just a certain amount of electrical current without issue. However, if that current level is exceeded, it will rapidly heat up and melt, breaking the circuit, and therefore protecting everything else in that circuit.
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[@ExtraSimplified]

Ohm's Law Explained: kzbin.info/www/bejne/foLIfISrdr12osU Why Cars Have Relays: kzbin.info/www/bejne/qmanhmiubL-tbZY How to "Read" a Tire: kzbin.info/www/bejne/b4GYpGaPfJyribM

[@davemcguigan218]

Thanks for showing this illustration, it is less con(fuse)ing now!

[@CarsSimplified]

Clever! Thanks!

[@802Garage]

Hah, good one.

[@aaronmcdonald4944]

Thank you. I know it's a simple concept but you still clarified a few questions that other videos didn't quite answer. thanks a lot!

[@leirahsing6119]

Thank you for taking your time to making this topic. Made it much much easier to understand. Great advice and tips!

[@CarsSimplified]

Thanks for the kind words! I'm glad it helped!

[@aunderskaizen]

Thank you 🙏 It was simple to innerstand, concise, and the visuals went a long way. 👍

[@802Garage]

Nice overview! Lots of important lessons to learn in this quick vid.

[@CarsSimplified]

Thanks! I tried to pack them in. It was a lot longer than I was expecting when I started, too!

[@phishtahko5951]

Awesome job explaining everything and very simple to understand deserves more credit than its got.

[@aldrinlapis4468]

Im just starting my apprenticeship as a mechanic and your video gave me a basic but complete understanding of fuse. Well done

[@arosseries1897]

You are an excellent instructor.Keep up the excellent work.

[@JoeyvaughanWorldBluesAttack]

Nice video! It was just what I was looking for!

[@jpramirz376]

Great video, explained it really well and now I have better understanding of it. Thank you

[@Maazin5]

This video answered so many questions I had about electricity. Thank you so much!

[@Snsndndnhshh]

Best teacher 👨‍🏫 . Very simple and easy to understand.

[@peternjenga679]

This is so well explained. Thank you 🙏

[@marsoelflaco5722]

Well put. Thanks. 👍🏽✌🏽

[@GlasscelSimpson]

Excellent !!well explained making it so easy to understand good teaching.

[@petetherealrelentless6542]

Great video. Nice and concise.

[@richarddrawsstuff2728]

Very good presentation. I might need look over the video a few times to understand but that just me. Thank you for the video!

[@jdmspirit99]

Very useful! Thank you

[@crazyartistvinitfiji4168]

Amazingly explained, i definitely learnt something.....

[@PorscheMonster]

Great explanation!

[@user-mj2yi7cs8q]

Wow that was explained very clear😳 good job bro, and thanks for the knowledge 🙏

[@ericross5048]

Great Vid, thank you!

[@CarsSimplified]

Thanks!

[@quantangoc2580]

Keep up the good work dude, liked and subcribed. Hope to see for more. Thanks for sharing the knowledge.

[@CarsSimplified]

Thanks! I will try to keep sharing the knowledge on a regular basis!

[@ericozeta9997]

Excellent video

[@joshinikhil6263]

Awesome explanation dude

[@yowzakaan7766]

Answered all the questions in my head best video, people like you man makes Jobs so easy you definitely earn the subscribe my friend

[@averagecrim2870]

i absolutelly love your channel searching about these things by car is not working at all so then generally learning about it at this channel it is! aha

[@Mpanagiotopoulos]

Very nice and clear explanation,hope your channel grows bigger

[@CarsSimplified]

Thanks!

[@michaell3711]

Great explanation to anyone without electrical knowledge.

[@mayureshkulkarni5664]

very well explained ! keep uploading such videos. Now, I am subscribing your channel.

[@TeeTafoya87]

Great vid!!

[@NickJThibault]

thank you !

[@leoshedden9199]

Thank you

[@Opreza12]

Very nice

[@alanchanthavisouk8557]

I like this video. Hope u do more.😊

[@simonia3178]

Sir, thank you

[@user-po4ts8xq8u]

Thank you for learn as and im ask what happens if a fuse is greater than required in the car manual?

[@andufuse640]

Nice

[@andrewmosesyanez9486]

so the im understanding that the purpose of a fuse is to break instead of another or other more expensive things essentially in case of a surge

[@thew4rrior5code]

Great video! This would explain why my new led dome light blew the fuse because it was about 4mm out so me being a noob I must of increased amps because it didn't fit properly lol. Lesson learned

[@CarsSimplified]

Thanks! If that 4mm was enough to touch a grounded piece of metal nearby, it could have caused a short for sure!

[@thew4rrior5code]

Cars Simplified I guess that's why they say get the correct sizes oh well at least they fitted in the number plate lights lol

[@andufuse640]

good

[@NMFree300]

Your the man!, is there any way I can learn more about the electrical side of the vehicle?

[@CarsSimplified]

Thanks! I have a few more videos about electrical parts as well as basic concepts, and I intend to make more, too! Here's my video on Ohm's Law, a good starting point for basic electrical understanding: kzbin.info/www/bejne/foLIfISrdr12osU

[@NMFree300]

I look forward to watching your Videos, thanks! 🙏🏽

[@mathspill7527]

Great❤

[@rockman531]

Hi, I know there's silver in some of the glass tube fuses - but is there any silver or other precious metals in the colored flat plastic fuses? Thank You very much!!

[@sirfairplay9153]

11/10

[@janalleman1286]

Hi, thanks for the video! i dont understand why the amperage is the same the entire path.. In my mind, after the resistor it is lower and then becomes the full amperage again once it has passed the battery. Can someone explain this?

[@frikkiesmit327]

Wise advice. I know a guy who made a mistake which blown a fuse and instead of checking why fuse blow. He went and put a bigger fuse in. And so the clients vehicle got a smoke machine in few seconds. Thats sarcastic. The whole harnass of wires burned from the fusebox to radio.

[@Ballu12345]

Thank you for Confusing me more

[@CarsSimplified]

What part is the most confusing?

[@masondashgarcia1535]

I have a starting issue no crank, it's a 2014 Chevy Colorado. Can I use any fuse to replace for the ignition fuse /starter fuse ?

[@justanotherdashcam24]

My mother's 2005 hyundai accent gls has a few electrical problems (doors won't lock, side mirrors won't move, window on front passenger side only goes down, clock buttons do nothing) I've checked all the fuses but there's none blown and without a multimeter or the proper knowledge of how to use one I'm limited to what the issue might be. With a little research online I found that it might be the diodes, my question is, is it possible to swap the diode from the inside of the car fuse box with the one in the engine to see if it's one of them or will that cause further problems?

[@killawattgarage]

A bit off topic but I would like to know how the battery charge indicator window works. What is it that creates the green/black/red colour? Video idea??

[@CarsSimplified]

That sounds like a great video idea! I would have to research it and get some footage of one. They are so uncommon around me that I have only seen a few in my life, and I've changed hundreds of batteries.

[@user-ex2rk6gj1h]

Skool never end

[@Chitown388]

If I tap a 5A fuse in the fuse box for a new circuit with a 20A fuse (using one of those fuse taps), will the new 20A circuit melt the (+) wire for the 5A fuse?

[@DMACAVILLION]

My positive wire leads into the bottom side of my fuse box on my SUV, i found a couple of plastic pieces I can pinch it barely open the wall sleeve, but I can't get to the under side of the connection,starting to break plastic...how does this fuse box come undone so O can change out the cable and fuse?

[@MrUnderEstimated]

this may be a dumb question but.... what will happen if the bulb and the switch switched places and there was a ground in between the bulb and the fuse?

[@babybackculturenews8818]

The power comes through the negative first

[@scrapinpennies4365]

So to put it very simply, a fuse is a failsafe to protect other components in a curcuit from damage.

[@badrijan9704]

Hey there need some help, can I use 5amps fuse instead of 3 that was originally? I have mounted a dashcam there and it burned the 3amp fuse

[@CarsSimplified]

I replied to your comment on the other video, but in case someone sees this comment and is curious about an answer, here it is copied from the other video: Assuming that 3 amp fuse is what the manufacturer calls for, that is a bad idea; the circuit (dash cam, wires, etc.) is designed to handle a given amount of amperage, and when it gets too high, that 3 amp fuse protects it. A 5 amp fuse will not offer the protection it needs. If it burns another 3 amp fuse, there is a problem elsewhere.

[@badrijan9704]

@@CarsSimplified thanks for your fast reply!

[@andufuse640]

we make fuse and fuseholder for car .

[@JesusLopez-ht1bg]

So if I take off a fuse for whatever reason it won't turn on is it a specific one

[@lilbutts5107]

Good video but there’s one thing I’m stuck on. Say if your light bulb takes 5 amps would u want your fuse higher amps than the light build but less than the wire so the fuse doesn’t keep blowing out. So for example 5 amp light bulb with a 7 amp fuse and 10 amp wire?

[@CarsSimplified]

That's a good set-up you described, yes. The wire being able to handle 10 amps means the 7 amp fuse will be what burns out if a fault causes high amperage.

[@lilbutts5107]

Cars Simplified but what if a fault was at 6 amps and went pass the 7 amp fuse and destroyed the 5 amp light bulb? Sorry I’m quite new to this, appreciate your time

[@CarsSimplified]

Ah, no worries! The bulb being a 5 amp is basically the most amps it will use at a given voltage. A high amp fault would be like a shorted circuit to ground, or power going to the wrong component. I may do a video on this now, it's getting difficult to describe without a visual aid. But, specifically 6 amps would be an odd way to fail, and it would have to be due to bypassing the bulb in some way, or installing the wrong bulb. In that situation, though, with a 10 amp wire and 7 amp fuse, the fault would be able to just continue, but is low enough that it shouldn't cause any damage. There may be other issues happening, but that would have to be discovered.

[@ahtoh1]

Check cheap CHINA fuses as some don’t blow and damage circuit.

[@mikej3844]

Does fuse color mean anything?

[@CarsSimplified]

It was supposed to be a quick way to identify the amperage rating, but sometimes the colors aren't 100% standardized.

[@tenncoin]

What happens when they use 5 30A fuses on the same jumper? If it a 150A fuse or just a heavy duty 30A?

[@CarsSimplified]

I had to look up the jumper and see what that was, since I don't deal with them, and I saw the part that taps into a fuse as well as some other options, but I'm not sure how you could add more fuses to it. But, I can say that putting multiple fuses in series means that that circuit will be protected by the weakest fuse (even if they are all 30 amp fuses, they might actually be 29.98 amp, 30.05 amp, 30.22 amp, etc. thanks to imperfect manufacturing) in that series, and putting the fuses in parallel will mean you add the amperages together, and any imperfections get multiplied (if they all say 30 amp but they are actually 29 amp, five of them in parallel would be 145 instead of the 150 it implies, and that works in reverse, too; 31 actual amps would become 155 amps) and you would also blow all five fuses as soon as the first one goes. Neither option is ideal because they introduce more imperfection variables, more complexity, and more cost. If you get one of those taps to add a circuit, if it has one fuse, that is likely going to run into issues I can explain if you're curious. The two fuse version should be splitting the circuit off before reaching each fuse; if it is designed that way, then each branch has one fuse on it, and that is how most fuses work before dealing with jumpers in the first place. I think I'll make a video on this; it's definitely something I can explain better with visuals.

[@tenncoin]

@@CarsSimplified I was asking because I'm working on a PEAK 1200 watt Mobile Power Outlet PKCOM12 and it has 5 30A fuses soldered to the board and was thinking solder a 8 gauge wire to each side and use a 150 breaker on the outside.

[@CarsSimplified]

That might work... Are the fuses on the 12V DC side or the ~110V AC side?

[@tenncoin]

@@CarsSimplified 12V side at the input

[@johnchristopherrobert1839]

The negative flows to the positive. Your flow of electrons is reversed.

[@Earth-Angel-639]

how is that possible considering that the battery amp is well above 150 amps

[@CarsSimplified]

If you are referring to how a 10 or 20 amp fuse doesn't just blow when a battery with a higher amp rating is powering the car's electronics: A battery's amp rating is a maximum it can do (but it's more complicated than that) and each fuse is a parallel brach, so if one circuit draws 5 amps and another draws 20 amps, the battery cable will have 25 amps going through it until it splits into those two circuits. The amp rating on the battery is more important for starting, since that uses a lot of amps.

[@etiennerojas2987]

I had a total of 5 fuses burned out. But. I ended gettting a new altanatore and a battery. It still was giving me eletrical problems the headlights would. Dim low and i had loss of power turns out it was number 10 20 and 40. Fuse. Only a total of 15 bucks wooow!!!

[@sergioin3D]

Can I upgrade my car fuse ?? Because it always blows with my car charger for my iPhone

[@CarsSimplified]

A majority of those chargers draw about 5 amps, while the lowest fuses for those plugs tend to be 10 amps. Something is going wrong, and if you use a bigger number fuse, you will probably fry some wiring instead of a fuse.

[@biblebloopers946]

I thought the voltage comes out of the negative and goes to the positive

[@CarsSimplified]

That's what happens with the electrons/in electron theory. Conventional theory is easier to teach because the + and - symbols are counter-intuitive for a lot of beginners ("+" implies a surplus of something that needs to go where the "-" is). But you're right, electrons with their negative charge move from the negative post to the positive.

[@clinicalgamer6558]

I change my bulbs, and didn’t change any other thing, and everything’s been ok, it’s been like over 1 year

[@blackghost7226]

are those fusees water proof ?? please tell me some one ??

[@CarsSimplified]

I don't know of any automotive fuses that are waterproof in and of themselves, but there are waterproof fuse holders available for these.

[@blackghost7226]

@@CarsSimplified thanks

[@TheMoneysMaster2]

It doesn’t show what types of fuses there are

[@channeldiali]

Does the brand matter,???

[@CarsSimplified]

Not too much, but quality can be an issue because the actual amperage a fuse blows at is based on the fuse element inside, which may be off by some percent if not manufactured well. Sometimes that percent isn't enough to matter, but sometimes it is, and there is no telling which circuit is which. Also, on the bladed fuses, I've seen some manufacturers not put the test points in, so they aren't as easy to check with a multimeter.

[@channeldiali]

@@CarsSimplified I got some from Amazon but they don't fit my RAV 4 2015, they have longer pins, why is that? How can I know the correct ones??

[@CarsSimplified]

Usually that's a mini fuse versus a low profile mini fuse. If you look up an automotive fuse chart, usually it is pretty easy to compare them, especially if the chart has measurements for scale. The low profile fuses are a pretty new design.

[@channeldiali]

@@CarsSimplified also I have a brand new car but I see some fuses and rely missing, why is that ? Is that normal?

[@CarsSimplified]

Cars often have blank spots for features not on that particular car but on versions of it with additional features, or so they can add features later on. Sometimes they never add those features, so every single car has the same blank spot.

[@TranslucentOrigin]

Wh...What!!!!???

[@Raven-cf5qd]

One thing I don't think you went over is why exactly you don't want to replace a 20amp with a 30 amp fuse

[@SavageWhiteBread]

Mhmmmm

[@citylockapolytechnikeyllcc7936]

YIKES, lot of missing info, and some assumptions I must question. Most importantly, I cite was that "a 20 amp circuit should handle a 21 or 22 amp load". If this were the case, the inrush of turning on a high demand item would always blow fuses. Circuit is likely designed to carry 50-75% of the assigned fuse. There was no mention of fuses on the "internet" market being defective in design, and not blowing as implied by their amperage markings. This is more critical than anything on the topic. You test a fuse as a diagram..... had you hooked up actual wiring and a power source, you might have been surprised, if generic fuses were in place. Anyhow, the intent was honorable, but the research and prep seemed lacking. I know, I should not criticize if I have not done a better video.... but misinformation can be very costly to those relying upon it.

[@annalivings6660]

All I want to know is do the new fuses stored for a long time expire or can one still use them new in a package that is 20+ years old?

[@CarsSimplified]

Unless something really bad happened to them like water corroded them or they are otherwise visibly damaged, they should be as good as the day they were made.

[@skid3339]

does it matter if you flip the fuse 180 degrees ? will it still work? or does it let current flow only in one direction?

[@CarsSimplified]

A diode (which some vehicles have in the fuse box and looks like a fuse, but not clear and with a diode symbol on top) will only work in one direction, but a normal fuse should work whichever way you plug it in.