Easiest way to hook up a horn - Team Camaro Tech
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post #1 of 6 (permalink) Old Jun 10th, 10, 06:43 AM Thread Starter
Senior Tech
 
Join Date: Oct 1998
Posts: 630
Easiest way to hook up a horn

Got a 68 camaro and have tried this before so I will try again... The wiring is funky but the car runs like a top. Originally was a race car at some point so it has stripped away marker lights, directionals, windsheild wipers, horn etc... the car has a trunk mounted battery, Alternator with an internal voltage regulator and 1 wire... So the normal horn relay is GONE... I know on the original ones there was a red wire that went to the bus bar from the battery. the other side of the bus bar has a fused black wire that feed power to the main fuse box in the car powering the entire car. there was a wire for the horns and a wire from the steering column, the pink/black wire was for the buzzer.... The car has power powering it from somewhere but not from the original place.. So my question is.

1. What is the easiest way to get horns without worrying about being stock or original?

2. If I buy a horn relay can I just feed power from the battery to bus bar, hook in the wire TO the horns and hook in the wire FROM the steering column and leave it at that? Can I just leave the other part of the bus bar empty? What is the pros, cons or problems with doing that?

Basically I just want to be able to put something together where I push the button and the horn blows.. plain and simple.. Oh and diagrams and explainations on how it would work would be great! Thanks In ADVANCE!

Mark
TOOFUN
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post #2 of 6 (permalink) Old Jun 10th, 10, 08:34 AM
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Jim
 
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Location: Saint Louis, Missouri
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Re: Easiest way to hook up a horn

You need a momentary ground from either the steering wheel horn button or from a push button or toggle switch.
This momentary ground then goes to a relay. The relay can have 4 or 5 terminals and should be rated at 20A or higher. Most aftermarket relays are marked with numbers on them on the bottom.
The momentary ground from the steering wheel or switch then goes to terminal 85, a constant fused power must then go to terminal 86 and 30, and then terminal 87 would go to the horn (which is then grounded either through it's mounting or a ground wire on it). If the relay has 5 terminals, then 87a will not be used.
Now when terminal 85 is grounded it powers up a coil inside the relay and closes a set of contact points to send power from terminal 30 to terminal 87 and out to the horn.

Jim

1974 Spirit Of America Nova (being restored), 1973 Nova Custom, 1968 Chevy II (Garage Find 2012)

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post #3 of 6 (permalink) Old Jun 10th, 10, 09:43 AM Thread Starter
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Re: Easiest way to hook up a horn

OK but do I need to put a fuse in line between the wire going to the relay and the battery + terminal? and if so how big? I have included a diagram on how I think it should be wired with the bosch relay... could you verify this diagram as well as whether I need that inline fuse or not?

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thanks
Mark

Last edited by mark67ss; Jun 10th, 10 at 10:58 AM.
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post #4 of 6 (permalink) Old Jun 10th, 10, 05:45 PM
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Steiner
 
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Location: Lyman, SC
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Re: Easiest way to hook up a horn

Looks good to me. Yes, use one of those little 30A $3 blade-type waterproof fuse holders from the parts store and put it on the 12V line right at the battery post. Horns can draw a bit of current. Those Blazer hi/lo sets at most parts stores draw around 20A. That will protect the entire cable and circuit should it get nicked.

'69 Camaro
Dart 400-AFR 195-224/224 HR-Powerjection III TB with F.A.S.T. Sportsman XFI
TKO 600-Moser 3.42-Detroit Truetrac
500hp/538lbft

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post #5 of 6 (permalink) Old Jun 10th, 10, 06:23 PM
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Jim
 
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Location: Saint Louis, Missouri
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Re: Easiest way to hook up a horn

Looks good to me also and like Steiner said, install a fuse right at or as close as you can off of the battery.
The wire size probably being short runs could be 12-14 gauge. No need to go up to 10 gauge.

Looking at this again (and I've wired PLENTY of relays like what you have basically drawn) is to change or reverse what wires are going to terminals 30 and 87. I've read about doing this before and I forget about doing it this way but if you have power going to terminal 30, then 87a also has power coming out of it when the relay is not being triggered or activated. If 87a is left exposed in this wiring configuration then it "might" be easier to hit this with something and short things out and blow the fuse at the battery. Now if you were to wire up the main input power to terminal 87, then terminal 30 will have power coming out of it when the relay is triggered by the horn button and when it's off terminal 87a will show no power. Basically, less chance of having a live terminal out of the relay that could be shorted.

Just thought I'd add this.

Jim

1974 Spirit Of America Nova (being restored), 1973 Nova Custom, 1968 Chevy II (Garage Find 2012)

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post #6 of 6 (permalink) Old Jun 10th, 10, 06:35 PM
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Steiner
 
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Re: Easiest way to hook up a horn

Jim, you bring up a good point about the run lengths. Might want to supply the relay off the alternator post instead of battery since it's a trunk mount. It would be a good time to put in a junction block but I get carried away sometimes.

'69 Camaro
Dart 400-AFR 195-224/224 HR-Powerjection III TB with F.A.S.T. Sportsman XFI
TKO 600-Moser 3.42-Detroit Truetrac
500hp/538lbft

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'02 Z/28 vert-stock-sold and totaled
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