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Discussion Starter · #1 ·
Hi all,

Not sure if this is in the right spot or not but here goes. I tried searching around the forums without much luck aside from people saying the horn was wimpy.

So I just got new (to me) 2010 mazda3 GT Hatchback. It's been driven pretty extensively (~125000 km/78000 mi) but looks to be in relatively good condition. There are a couple things I'm trying to work on but the most confusing one right now is the horn.

I've heard lots of complaints about the horn on Mazda's and that this is a pretty regular problem so when I discovered how wimpy the horn sounded I decided to try my hand at repairing it. I was surprised how poor the sound was, to the point where I thought something was actually wrong with the horn itself, it sounded almost fluttery, as if the sound was cutting in and out very quickly. I also noticed (after having the car for a few weeks) that the previous owner had drilled some holes in the black cover above the fog lights, possibly in an attempt to make it louder (he didn't seem very mechanically inclined)

So I picked up a 2005 Jetta set of horns and went to install them. Before opening up my car I mounted the new horns onto an aluminum plate, wired them in parallel, and drilled holes in the plate to mount it in place of the old horn. I tested this new horn assembly on a spare battery and it sounded great! However, once it was installed it sounded wimpy, making a similar fluttery sound. I tested it a bunch of different ways to try and uncover the root problem, see some of my tests below:

Horn on floor, wired to spare battery = GOOD
Horn bolted down tight, wired to in-car battery = BAD
Horn bolted down tight, wired to spare battery = BAD
Horn loosely bolted, wired to spare battery = GOOD
Horn bolted down tight (insulation between plate and mounting arm), wired to either battery = BAD (but better)

So I've narrowed it down to being a mechanical issue I think. The fact that I can have a bad sound, loosen the mounting bolt by 2 turns, and have a good sound, tells me that there is some sort of vibratory interference causing the wimpy sound.

Here's how I have the horns set up. Horns mounted to plate using their nuts on their rear bolts, two holes drilled in plate to match up with the one painted bolt and threaded hole where the old horn was mounted. Hot wires are soldered together and attached with a connector to the hot wire the old horn used. Grounding wires of the horn are soldered together and then to a wire with an eyelet. This eyelet is then put between the plate (after being shined up with some emery paper) and the mounting arm (also shined).

Any thoughts? Can provide pictures/recordings if you'd like.

Tom
 

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Discussion Starter · #3 ·
Good idea!

No I hadn't, that is worth a shot I suppose. I had sort of ruled that out since it worked without one when hooked up to my spare battery. Maybe I don't understand exactly what the relay does, but if it is working without one, doesn't that eliminate the likelihood that it is the source of the issue?
 

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Good idea!

No I hadn't, that is worth a shot I suppose. I had sort of ruled that out since it worked without one when hooked up to my spare battery. Maybe I don't understand exactly what the relay does, but if it is working without one, doesn't that eliminate the likelihood that it is the source of the issue?
It may have worked correctly running DIRECTLY off your spare battery (horns>battery), but when connected to the car it isn't. It is going (horn button>relay>battery>horns)
The circuit in the car may not be strong enough to allow the horns to work correctly.
Example my Hella's are wired on their own relay that came with them. It still uses the stock circuit but it only uses that as the trigger.
Did your stock horn work correctly? Did you rewire it back in to see if it still works correctly?
 

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Discussion Starter · #5 ·
It may have worked correctly running DIRECTLY off your spare battery (horns>battery), but when connected to the car it isn't. It is going (horn button>relay>battery>horns)
The circuit in the car may not be strong enough to allow the horns to work correctly.
Example my Hella's are wired on their own relay that came with them. It still uses the stock circuit but it only uses that as the trigger.
Did your stock horn work correctly? Did you rewire it back in to see if it still works correctly?
The old horn never worked but the reason I think it isn't an issue is because of some of the testing I did:

spare battery>new horn (bolts tightened) = wimpy sound
spare battery>new horn (bolts loose) = strong sound

Hence why I'm so confused. It would be nice if it was something like the relay because then I'd know the source of the issue but I'm not sure that's the case here.
 
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