Horn fuse keeps blowing

The factory horn fuse, because the train horn runs off of the same fuse.

 

Also, the fuse blew on a long blast. Was honking at a friend when it went. And the compressor is not hooked up to the horn fuse that i know of.

I'm very confused/overwhelmed by all of this. REALLY don't want to cause any damage to my truck.

 

If your compressor is not hooked to your horn fuse then try the 15a fuse. If
It doesn't blow ride with it. If it does you may need to rewire your horn.

 

My factory horn circuit triggers a relay, and that relay operates a dump valve for the big horn. No problems here because the control side of this relay has a very low draw. If you need a larger fuse, the wiring for this system needs to be re-evaluated as mentioned earlier.

 

Relay it, just use stock wiring for trigger. Upsizing fuses is a no no.

 

Yes, it can.

A 10a fuse will be protecting a circuit using as small as 20ga wire.
A 15a fuse requires wire no smaller than 18ga... bump that to 14ga if in an enclosed area (like stuffed into a wiring harness under your dash).

Toyota used 10a fuses because 10a fuses are what was required to protect the wiring in the truck.
Installing a 15a fuse without upgrading the wiring is simply ignorant and stupid.

And in the application that he is describing, he either has a short or has something mis-wired. The horn requires 30a, if he's blowing a 10a fuse, he will probably blow a 15a fuse.
Are you going to tell him to go ahead and plug in a 20a fuse?

He has a problem with the circuit and it needs to be resolved. Simply replacing fuses every time they blow is not the proper or safe way to do it.

 

The train horn needs to be on it own (30a?) fuse with 10ga wire feeding it all the way from the battery through the relay to the horn.

Simply connecting the train horn to the factory horn fuse with a separate wire is not much better than connecting it at the factory horns.

 

Put a 30 a fuse in it. Or just use a wire.

 

Are you kidding me!?!? This is by far the worst possible post in this thread.

This guy is seriously overwhelmed and scared shirtless cuz you guys are all mentioning fires and he doesn't know shit about electrical and can't rewire with a relay on his own. Telling him to just throw a jumper wire in it or a 30amp fuse is just stupid. Are you trying to catch his truck on fire??

-1 for this post.


OP, relax for a minute. I am a professionally certified mobile electronics technician and know quite a bit about circuits and amperage. This situation is not nearly as bad as people are making is sound. You obviously have a wiring flaw, but its fixable. Right now your truck isn't gonna blow up or catch fire like everyone is making it sound.

I know you say you are electrically challenged and don't much about how this wiring stuff works, but I will do my best to walk you through this.

Because you say it blow occasionally but not every time means that you aren't pulling an excess of 10amps all the time. It seems to just be sometimes, which leads me to believe that when in fact you do pull more than 10 amps, its not too much more than 10.

I would normally NEVER recommend putting a larger fuse on an OEM circuit because what people are saying is true. It is a fire hazard, and not exactly smart practice. BUT, because this fuse pops occasionally, I would actually recommend trying a 15amp for a limited time to see if it keeps blowing or not. If it stops blowing the 15amp fuse, then my professional opinion, although not typical, is to go ahead and leave the 15amp fuse in place for good.

I say this for 2 reasons. First of all, the risk of a 15a fuse in a 10a circuit causing a fire is slim to none to be honest. And second, since trying to walk you through a complete rewire would be extremely difficult, its not worth all the trouble over just a few amps.

Now, with that being said, I can honestly say you'll be safe with the 15a fuse in there, but please do not make this normal practice. Generally speaking, its not smart, especially if you don't know what your doing. The wiring in this truck is designed to handle more than its actually fused for, so a small 5 amp upgrade won't hurt your truck or you. Anything more than 5a above the original limit is not safe at all.

If the 15 amp fuse blows, do NOT exceed that and try a 20a. A rewire will be required at that point. I do recommend that you have this professionally redone the correct way using a relay, but do not attempt this on your own if you have no clue about electrical. The 15a fuse is like a bandaid. It will help get by for now, but you should eventually get this rewired regardless.

I just want you to be clear that my overall professional opinion is a rewire using a relay, but please don't get so scared by all these other posts thinking that the 15a is going to blow up your truck. Like I said, its not recommended, and not good practice, but in all reality, that small of a change isn't going to hurt anything.

 

I'm glad to see that someone else knows that 5a isn't going to burn the truck down. My 30a post was a joke since people are going over board on a small fuse. I also do nothing but play with electricity all day every day. DC and AC. Have been doing so for 10 years. Yet to burn anything down. House or car.

But somebody will quote your post and say

NO NO NO NO

Op. good luck

 

Glad to known your post was a joke. I was like seriously wtf did this guy just say. Lol

I think what is going on here is that we are failing to realize that there is an aftermarket component involved in this circuit now. If OP said my regular horn keeps blowing fuses but nothing else is connected to it, then obviously there is a problem with the OEM circuit and a larger fuse is not a fix for this. That would straight out dangerous.

But, the fuse is blowing simply because of excess load caused by an "aftermarket" add on to that circuit.

Consider this, how many people use those add-a-fuse things to add accessories and such to their vehicle...? A lot! These add-a-fuse products are essentially the same thing. You unplug the OEM fuse, and insert this thing that now accepts 2 fuses and branches the circuit into 2. People double their 10a OEM circuits with 2 10a fuses and not a single person has reported an issue that I am aware of.

Yes I understand that the majority of the time, these add-a-fuses are being used to trigger a relay and consume small amounts of voltage, BUT, why then are everyone using 10a fuses in these instead of a 2.5? If something went wrong, they would be screwed.

My point is that I do 100% agree with those saying its unsafe practice and not recommended. True. But, if the excess load exceeds the 10amps by only 2 or 3 amps and the wiring is know to not have any shorts, then replacing this 10a with a 15 is the same as essentially using and add-a-fuse. Like I said though, if the 15 still blows, then this bandaid type fix is not going to work at all. I do highly recommend a professional rewire as soon as possible. But if the 15a works, in all reality its not going to hurt anything. The excess load isn't enough to melt the box, connectors or wires. Toyota and all other manufacturers make them capable of withstanding more than the just what the OEM fuse is rated for. Not by a lot, but enough to cover this situation just fine.

I would make a how-to and draw up some diagrams, but being that I have no clue how its wires to begin with means this could take days of messaging back and forth to figure out where to even start. I simply don't have that much time right now. I recommend OP going to a reputable shop to resolve this locally

 

Thanks for finding my old post and quoting it. Might help OP. If not, I think this is as far as I go in this thread. Pictures if burnt down cars and shit is just obnoxious and uncalled for. Other guy already stated his 30a fuse comment was a joke, no need to scare the hell put of OP even more

 

This is an even more idiotic statement than the picture you posted. You call yourself an "electrical engineer"
im your profile, but you assume anyone who doesn't know as much as you is going to burn down their car sounds pretty self centered if you ask me. Go ahead and report me, but your a There was once a day when you and I and every other electrically inclined person didn't know a dam thing about electrical... did we all burn down our cars? No. Assuming anyone who is trying to learn is going to fail is an ignorant assumption. You have contributed absolutely nothing to this thread except your ignorance and over sized ego. Good luck with your future.

I didn't think it was appropriate either by any means, that's why I blew up about it, but luckily he cleared it up. Water under the bridge.

Thanks for your consideration and kind words. As much as I'd like to stay and assist OP, other peoples ridiculous comments are driving me up the dam wall. I feel bad for OP, and if he wishes to PM me for further assistance, I will help. But for now, I'm out. Thanks again man

 

5a over a 10a is 50% over the design spec.

Would you put a 30a fuse into a 20a circuit?
Would you put a 45a fuse into a 30a circuit?
75 in a 50?

Same thing.

Proforce is right, the 15a will not likely cause any problems, but my concern is that there is an underlying problem that needs to be fixed. OP stated that the fuse blew on an extended honk, so it's not pulling much over 10 immediately, but it is pulling enough to get that fuse hot and melt it.

Personally, I would use the 15a as nothing more than a temporary test, but I can get in there and track down the problem too.
For the OP, if the 15a works, just resist the urge to lay on it for a long honk.

 

Slight difference though... the supply side of that add-a-fuse is also supplying the rest of the fuse block, so it's not really branching a 10 into a pair of 10s, but rather adding a 10 onto an existing 25a or 30a supply (and I know you know that )

I don't
Seriously... I generally go with a 5, even though I'm usually never using anything smaller than 18ga in a vehicle.

My concern is he (or whoever wired it) made a very common mistake and wired the switched lead to the relay's contact pin.
I've helped more than one person who complained that they were blowing fuses, or that their battery was going down.
Switched lead to a contact and battery to the coil will do that.

Simple fix, but not easily done without being there unless you know what circuit design the poster used.

In this case, it makes no sense... he said the train horn is connected to the battery with it's own fuse... then why is the truck's fuse blowing?
It sounds like the truck is still feeding the compressor directly.

 

You can always tell an engineer.... but you can't tell him much

Seriously, some of the sharpest people I know are engineers.
Also, some of the biggest blow-hards full of head knowledge but 100% lacking in actual hands-on.
I encountered a guy who actually taught classes in traffic signals at a community college.
He burned up 3 bits before realizing his drill was running reversed.

 

First and foremost, I am still overwhelmed becasue I don't want my truck to end up like that Chevy haha.

But thank you all for the help. I am going to take some pictures of the wires later today and post them in this thread.

After reading this and talking to a friend yesterday, i may be able to do a rewire with all of this info and his in person help.

I checked the wire from the battery yesterday, and the inline cylindrical fuse is 30 amps. So I don't know exactly what that is hooked up to.

 

I checked the wire from the battery yesterday, and the inline cylindrical fuse is 30 amps. So I don't know exactly what that is hooked up to.[/QUOTE]

That should be your power for your compressor.

 

First thing, remove that fuse and see if the horn still fires.

If it does, you've found the problem.