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Your electrical friend
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2,177 Posts
Discussion Starter #1
I posted this at SR20DEforum.com as well and wanted to share it with people over here who don't frequent that site.

I just put my air horns in the SE-R that used to be in the XE and wanted to share the outcome so that anyone thinking of doing air horns might benefit from it. In the XE I had the horns mounted to a bracket that I attached to one of the radiator mount backets. The SE-R has all that EGR crap in the way, so I couldn't find a good location. Then I realize there is tons of room behind the airdam and plenty of places to mount brackets. So I mounted my bracket sandwiched between the vertical front clip brace that also has the hood release mechanism mounted to it. This allowed me to put the two air horns behind the dam, out of sight, and protected from the elements. I used the OEM horn bracket to mount the compressor, which is just above the bumper, but still behind the bumper cover and can't be seen through the grill.

Here's a pic of the compressor.



The horns behind the air dam.



There was enough room that a person could mount a triple horn easily, and with a little coersion, a pair of duals or a 5 horn setup. There's even threaded holes on the bottom side of the front clip where a person could attach brackets. You can clearly see one of these holes rusting, just to the right of the horn. :)

Here's my inline fuse holder that I zip-tied to the throttle cable. I used the OEM horn wire to operate a relay which operates the air horn. The air horn pulls a lot more current than the OEM one.

 

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Longtime DSMtalker
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123 Posts
Hey man, I just got a free (used) air horn set.
And need some help as it came with no instructions.......
Using my small amount of functional gray matter, this is what I think it should be.
The horn is negative triggered, right?
So the #85 relay spade gets a splice from the negative wire going to the factory horns? Or does it get a positive splice.
Spade #30 gets constant 12 volts, right?
Spade #87 goes to the compressor.
Does #86 get a ground or positive?
Confused.........anyone who has done this help me?
Thanks!
 

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Your electrical friend
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2,177 Posts
Discussion Starter #3
I don't know about your car, but my B13 horn is positive triggered. Just use a multimeter on the OEM horn hookup wire to check for voltage while the horn button is pressed. Some horns are negative triggered but I don't know if your's is or not. If your horn is negative triggered, then you will hook the OEM horn trigger wire up to 85 on your relay, and 86 will have constant 12V. If your horn is positive triggered, then the trigger wire will go to 86 on your relay, and 85 will be grounded. Yes, 87 or 30 will go to the horn, and the other, be it 87 or 30 will go to positive voltage. If your relay has an 87a tab in the middle, you can break that terminal off, or just do what I usually do, and put an empty fully insulated female quick dosconnect on it, to keep it from ever grounding. You'll have to check it out yourself for your car, but b13's have an OEM horn relay, and if the wiring is up to par for the job, then a person could merely up the fuse size for the horn when installing an aftermarket horn (if it draws more current than the OEM one, which they typically do). If you need any further help drop me an e-mail or PM me.
 

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ex-Super *********
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1,410 Posts
1997 GA16DE said:
i think everything on the car is positive triggered except for the dome light and door sensors.
Oh, you have much to learn my friend.. Almost every ECU output in the world is neg switch, Igntion coil..neg switch. I could go on and on. The reason for this is that there tends to be less of an arc when you swtich the neg side of a load(at least that the reason I was given).

RELAY WIRING
85 and 86 - Give one power and one ground. To make it easy on you I say this.. Give 85 constant +12V and 86 ground, use a switch to make/break the ground side. (horn on/off)
30 - Constant +12V supply.
87 - +12V to your horn

If anybody has ever wondered what the extra terminal(87A) is, in this circuit it would have the +12v with the switch in the off position, when you turn the switch on internal contacts move and push the +12v through 87

I anyone wants a lesson in how realays work, give me a holla.
 

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ex-Super *********
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1,410 Posts
Or you could make it easy.. Make sure the stock horn relay has a high enough ratting for you new horn system, and just use the stock horn output to run the new system.. of course it would be the only horn you have then.
 

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Your electrical friend
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2,177 Posts
Discussion Starter #7 (Edited)
Originally posted by PatScottAKA99XE:
Or you could make it easy.. Make sure the stock horn relay has a high enough ratting for you new horn system, and just use the stock horn output to run the new system..
Yeah, and....

Originally posted by Toolapcfan:
You'll have to check it out yourself for your car, but b13's have an OEM horn relay, and if the wiring is up to par for the job, then a person could merely up the fuse size for the horn when installing an aftermarket horn (if it draws more current than the OEM one, which they typically do).
For future reference, the horn relay is rated for 15 amps and the wiring coming out of it is pretty small, 16 gauge at best, but I'm thinking more like 18. I couldn't tell what gauge comes into and goes out of the horn fuse, but the horn fuse is only 10 amps. So I'd suppose you can safely do a direct hook up if the horn you're installing doesn't pull more than 10 amps, or if you want to up the horn fuse to 15 then you could do that and go up to 15. (Actually higher than that, fuses will handle way more amperage than what they're rated for) Since horns aren't used continuously, you'd probably be fine doing a direct hook up using the OEM horn wire to operate it. I'm going to do a little more research before I decide to get rid of my seperate relay and fused power and hook mine up direct.
 
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