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Discussion Starter · #1 ·
Hiya Gang, I decided to replace the original horn on the 81CM400C as it sounded like it was stuttering and pushing about 40 decibels. Swapped it out with a denali sound bomb mini. No sound, just a little clicking noise so there's something happening. Swapped back the original and there's zero sound now. The connections all look to be okay. Idea's of where to start? I've got very little electrical experience, so pretend your talking with a caveman. Thanks!
 

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Caveman eh?

Normally I'd suggest a multimeter for all tests, but to keep things simple I'll recommend a 'test light'.

https://m.harborfreight.com/6-12-volt-circuit-tester-4288.html

Its a simple device, think light bulb with wires, one has a clip and one has a pointy probe. You clip one end to your negative battery terminal and use the pointy end to look for electricity on the connection you touch the probe tip to. Try touching the probe to your positive battery terminal, the light will light up.

My guess is you'll clip to the negative battery terminal and probe your two horn wires and find nothing. Now press your horn button and probe your two horn wires, one of them should light the bulb in the tester.

If none of the above will light up the light, you've got a wiring issue or a switch issue. You may also take some scrap wire and connect your old horns connections to your positive and negative battery terminals, if the horn honks you've got a strong battery and a good horn, try your new horn too.

Let us know how it goes, we'll help as you go.
 

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Discussion Starter · #3 ·
Thanks Alan, i've got a multimeter at work, I'll grab it tomorrow. I'm suspicious that it may be a bad wiring connection as the intermittent stuttering/volume of the old horn. I know the battery is good, and all the other electrical works fine. Does the horn have its own fuse or does it share duty with another component like a brake light for example?
 

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Alright, if you're familiar with operating a multimeter you're worlds ahead of some.

When I had my CM400C I only went through the electrical system once to get everything working, never blew any fuses so I can't help much, maybe check the wiring diagram in your manual, if you don't have a copy of the FSM Factory Service Manual shout out and someone will be along to pm you a link.

My 750 Nighthawk had a horn issue once and was blowing fuses. That circuit included the horn, turn signals and brake light.
 

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Discussion Starter · #5 ·
Alright, if you're familiar with operating a multimeter you're worlds ahead of some.

When I had my CM400C I only went through the electrical system once to get everything working, never blew any fuses so I can't help much, maybe check the wiring diagram in your manual, if you don't have a copy of the FSM Factory Service Manual shout out and someone will be along to pm you a link.

My 750 Nighthawk had a horn issue once and was blowing fuses. That circuit included the horn, turn signals and brake light.
Well, to be fair I only know "where" the multimeter is at work, not what to do with it ;-) I'll youtube it and see how it goes! I'm gonna go swap out the new Renthal bars, and install the bar end side mirrors for now and tackle the horn mystery tomorrow.
 

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Discussion Starter · #6 ·
So, I pretty sure I'm an idiot. But just to be sure, does the horn normally work when the engine isn't running? I'd been testing it with the power on but engine off. Started up the bike for a test ride after installing the new bars and the horn works great.
 

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Make sure there is a green ground wire from the harness behind the headlight that attaches to the bottom of one of the handlebar risers at the top triple tree. This wire brings the electrical ground to your handlebar switches. Depending on your new handlebars you may need to sand the finish off of a small area where the handlebar clamp with the ground wire connects. Also you may need to expose bare metal in the areas where your handlebar switches contact the bars to supply ground connection for your switches. With this ground, if there is some sort of loose wire or short a fuse will blow instead of you providing a ground path by getting zapped.
 

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So, I pretty sure I'm an idiot. But just to be sure, does the horn normally work when the engine isn't running? I'd been testing it with the power on but engine off. Started up the bike for a test ride after installing the new bars and the horn works great.
If your battery is a little low you'll have horn issues like that, always make sure to check your battery voltage before going for an inspection sticker as your turn signals and horn usually need to work without the engine running (for some stupid reason)
 

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So, I pretty sure I'm an idiot. But just to be sure, does the horn normally work when the engine isn't running? I'd been testing it with the power on but engine off. Started up the bike for a test ride after installing the new bars and the horn works great.
My bike has to be running in order for the horn and turn signals to work.
 

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If your battery is a little low you'll have horn issues like that, always make sure to check your battery voltage before going for an inspection sticker as your turn signals and horn usually need to work without the engine running (for some stupid reason)
Not so where I am (NY), bike needs to be running during the inspection.
 
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