Horn Relay Wiring Inline Fuse Question

[cowboyup3371]

I'm going to replace my horn over the next week as it's sounding like a choked duck after I tried cleaning it a month or so ago. I've done the searching, read the horn relay guide on Basscliff's site, and have a couple of ideas for the new horns. I fully understand the need for the relay and the principle behind doing the wiring modification and already have most of the parts I'll need. However, I'm not understanding why a separate inline fuse is needed from the battery instead of just using an open slot on the fuse block. Can someone explain that portion of the reasoning for me?

[tkent02]

A fuse is a fuse. A lot of bikes don't have open slots in the fuse block, or even fuse blocks. Also some folks may have used the open slot for a toaster oven of capuchino maching or something.

I just skipped the fuse completely, nothing ever burned up. Could I suppose.

http://cincinnati.craigslist.org/mcy/4221757522.html

[posplayr]

The whole point of the relay mods are to avoid using the stock fusebox with all of it's voltage drops including the wiring through the ignition switch. The wiring down stream of the fusebox(that between fusebox and horn) is less of a concern. So by powering your horn relay from the fusebox instead from the "T" you are relinquishing most of the benefit you had hoped to achieve.

The "T" is where the battery (+) and r/r(+) meet.j

[cowboyup3371]

Pos, you know more about electrical wiring and theory than I can ever hope to understand and your comment makes some sense. But, isn't a fuseblock really nothing more than a collection of inline fuses into one area? Why not just run every circuit to its own single inline fuse connected to the battery + if voltage drops are a concern?

To tie it in with something I'm more familiary with; my network switches take a number of 100 megabit circuits from a computer to a server or other device (depends on what we are doing) and consolidates them into one piece of hardware. I could very easily run 48 different lines to the server but it will be very cumbersome, expensive, and messy to do so. Therefore, i have 48 computers going to one switch using a single connection to another switch and then to the server.

In my mind, the fuse block does the same thing. If there are voltage drops from the ignition switch to the fuse block that are the concern, then shouldn't that be fixed for that and not just throw additional circuits into the mix?

[posplayr]

Pos, you know more about electrical wiring and theory than I can ever hope to understand and your comment makes some sense. But, isn't a fuseblock really nothing more than a collection of inline fuses into one area? Why not just run every circuit to its own single inline fuse connected to the battery + if voltage drops are a concern?

To tie it in with something I'm more familiary with; my network switches take a number of 100 megabit circuits from a computer to a server or other device (depends on what we are doing) and consolidates them into one piece of hardware. I could very easily run 48 different lines to the server but it will be very cumbersome, expensive, and messy to do so. Therefore, i have 48 computers going to one switch using a single connection to another switch and then to the server.

In my mind, the fuse block does the same thing. If there are voltage drops from the ignition switch to the fuse block that are the concern, then shouldn't that be fixed for that and not just throw additional circuits into the mix?

In only the most cursory way is your analogy between the ethernet switch and the your fuse box concept analogous as one is a fan in/out (ethernet switch) and the other is a fan out (fuse box) but beyond that the analogy breaks down.

Even though both are based on electricity the ethernet switch is designed based on the lower physical, data link and network layers of the OSI stack model. What that means is that it has been designed to deal with various issues of multiple signal, multiple signal collisions, signal cross talk, electrical loading, fan in fan out and the list goes on and on. By design you the user are insulated from all of this.

From a user perspective, all you really have to know is that any device connected through and ethernet cable that is connected to your switch can establish a connection to any other device that is similarly connected; ( i.e. they are all on the same network.) So as I write this I realize that even the fan in/fan out similarity only applies if you are a talking about having a gateway for example. The ethernet switch is really a star topology.

So the bottom line is that the reasons I stated are the reasons that people design relay mods, and those are the practical issues of resistance, and corrosion causing voltage losses and heat which compromise the performance of what ever you are hooking to the fuse box. The ethernet switch design virtually completely insulates you from any type of similar challenge and so there is really no reason or use in trying to tie the two together through your analogy. (at least none that I can see that would be instructive)

[cowboyup3371]

Pos although you are correct I believe you took my analogy the wrong direction as it wasn't made in the sense of electrical flow but in a collection of ports. However, I believe my question was answered through other means and I will proceed with my plan as I have it in my mind. May not be right but I believe it will work.

[posplayr]

Pos although you are correct I believe you took my analogy the wrong direction as it wasn't made in the sense of electrical flow but in a collection of ports. However, I believe my question was answered through other means and I will proceed with my plan as I have it in my mind. May not be right but I believe it will work.

I don't think I took your analogy the wrong way. I just pointed out that the ethernet switch analogy had very limited utility(other than the notion of a port) in understanding how motorcycle power distribution works because ethernet has all of the "electrical details " abstracted away (i.e. you don't have to know anything about ethernet to use it).

Not sure what your plans are, but good luck.

[JayWB]

The reason wiring the horn from the fuse box incorporates the whole bike's wiring harness and associated voltage drops is because very little of the motorcycle is fed DIRECTLY from the battery through the fuses. One would not wire the battery to the fuse box and everything else directly to the other side of the fuses because that would bypass the ignition switch.

Power for everything that operates only if the ignition switch is on actually runs all the way up to the switch and then back down to the fuse box. Along the way said power has ample opportunity to drop voltage across many (old and corroded) connections. If you wire your horn relay directly from battery voltage with an inline fuse there are no such voltage drops since it doesn't wander all over the bike.

You could, of course, put an ignition switch controlled relay in line with the fuse box so that the relay would eliminate the main power's trip up to the key switch, or you could just clean all the connections and make sure they are tight and corrosion free. Both would accomplish pretty much the same thing.

[quexpress]

You could, of course, put an ignition switch controlled relay in line with the fuse box so that the relay would eliminate the main power's trip up to the key switch,

That's exactly what I was thinking also while reading this message thread.

[argonsagas]

A small thing to consider....when stock horns fade or even quit they can sometimes be revived by using the little adjustment bolt on the back.


Use plenty of lubrication, penetrating oil and turn it in tiny increments only.


It worked for me...

[posplayr]

A small thing to consider....when stock horns fade or even quit they can sometimes be revived by using the little adjustment bolt on the back.


Use plenty of lubrication, penetrating oil and turn it in tiny increments only.


It worked for me...

They are funny that way. Same for me for a set of ebay horns nothing till I backed the screws out.

[Brendan W]

A small thing to consider....when stock horns fade or even quit they can sometimes be revived by using the little adjustment bolt on the back.


Use plenty of lubrication, penetrating oil and turn it in tiny increments only.


It worked for me...

+1 . Most seem to have forgotten about these and will get a new unit at the drop of a hat. Doesn't help that some units have a blob of sealer on the screw, effectively hiding it. Good idea to put some back after adjustment. One less way for water to get in.

[storm 64]

Plus it's fun to drive your neighbors crazy when tuning your horns

[tkent02]

Actually th horn scrws are easier to tune accurately at 3:00 AM.

[cowboyup3371]

I picked up a couple of Wolo DISC horns from OReilly's Auto Parts today:



And drew out the wiring diagram I had thought of doing:



Now I need to figure out what size fuse to use in that location