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Topic Review (Newest First)
11-03-2007 01:58 PM

did you ground negative connection to the car body? i have an ooga horn, and i just hooked up for fun today to test it ( i need to get something to mount it before it becomes a permanent fixture in the car) and it worked for me.. so try grounding the negative cord to the body of the car.
08-15-2006 10:00 PM
BobbyG-39 Doc, Elegant, and everyone else, thanks for your help.

In replacing my LeCarra horn button for Juliano's V8 button, I discovered both provided the ground and "relay" for the horn. In other words, the wire from the harness to the horn isn't "hot" or active until the horn button in the steering wheel is pushed down.
08-15-2006 12:55 AM
Drawing wiring

Hi Doc!

I use Corel Draw 7 to draw and Adobe's Acrobat to make those drawings into deeply zoomable PDF files. Corel 7 is an antique now, email me at for details.

I have been drawing with it for many years. Since I love car wiring and mechanical details I have sort of arrived at my own drawing style. Based on the 80 zillion posts you have done here, it is a fine compliment to receive a thumbs up from you.

Kindest regards

Jon P
08-15-2006 12:30 AM
docvette Doc here,

KEWL drawing and assessment..Elegantinventer!!

What did you do the art work on? anything I can Download on the web somewhere?

08-15-2006 12:22 AM
Horn Relay Circuit Drawn Out

The circuit Doc describes is what I have seen in just about everything I have ever worked on.

I have had to explain relay wiring many times, so here's my interpretation of the common "Bosch" style 20 and 30 amp relays and how to wire them safely with fuses.

Jon P
08-09-2006 12:46 AM
docvette Doc here,

Most standard HORN buttons are a spring loaded push pad..that activates a GROUNDED Contact (looks like a motor brush..carbon contact with a spring between the contact ends) that contact goes through the steering wheel inside of a plastic insulator, the other end sticking out of the bottom of the steering wheel..all of this part moves with the wheel..

The Column side has a "Copper Ring" that goes around the steering wheel shaft..(this part does not move ) and hooks to the black 20 ga wire in the column..the contact touches this when the button is pushed..and fires the relay coil by providing GROUND to the relay..sounding the horn..

This is why I was concerned when you said you applied 12 volts to the horn button wire..If you follow it have 12 volts at the bottom of the column..then when you sound the horn ground that 12 volts directly through the horn ring...ERGO...Smoke...Fire and wires going away inside the column..Dead Short..

You Should Not be able to run power through a standard GM horn button, as it mechanically grounds inside the column..

This is also why the relay is wired Power for the relay coil directly to 12 volts hot at all times...and relay coil ground to the horn button..

I hope you follow what I am saying..It's like taking a button and putting + from the battery on one side of the button, and - from the battery on the other..It's fine til you push the button..then you let out the factory installed smoke..

08-08-2006 10:21 PM
BobbyG-39 Doc, thanks, yes I assume the vehicle is re-wired. These do not look like 1939 wires- it appears to be a standard wiring setup one would purchase to put a whole new wiring set in the car. I did not do any of the rest-o-modification, ( and I don't have any experience in any of this stuff, ) so I am making some educated guesses.

Same thing goes for the steering wheel. I know its a LeCarra Banjo wheel, and I was told its a GM column by another more informed hot rodder. The "button" I refer to is the one in the center of the steering wheel. I hope we're talking the same thing. I don't know if its the standard GM horn set up or not. Basically, I want the button in the steering wheel to activate the horn, not some separate switch or button mounted elsewhere.

Funny you mention it, the horn button has gotten stuck a few times within its housing in the wheel, I assumed it was a funky or cheap button. I am going to buy a Julianos V8 polished replacement , is there any way I can see when I take off the "LeCarra" button if its grounded there??

One more note: I have had the car two years, and other than the button getting stuck a few times, the horn has always worked fine.
08-08-2006 04:44 PM
docvette Doc here,

OK, more questions..

Is the Vehicle re~wired?(new plastic coated wire as opposed to Cotton clad wire?) If not, on a 39 I am not sure about a stock relay, but I lean toward "I doubt it has one"...If aftermarket wiring it probably has..

And the second and more important question...I assume you are using an "Button" for a horn , not the standard GM horn setup..cuz...It's ground!

When you push the button on a standard GM horn button, it has a "Brush~like" device in the steering wheel that takes the black wire in the column harness , and GROUNDS it...this applies ground to the relay coil..which has power at all times.

If you are using it..and it is working for some reason, with 12 volts on are very lucky! for some reason the column is not grounded and it's only a matter of time until it the next time you push the horn .. it all goes up in smoke..(12 volts to ground..)

If however, you are using an aftermarket "Black Button or switch" I can see how that can work fine..however the safe way is to use the ground in either case..Assume every-time you hear a stuck horn, It's a ground hitting something on the horn button wires..Now change that to 12 have a burned up harness or fire..

To check if you have a relay a quiet location, disconnect the horn at the front, and push the horn button..listen for a "Click" and track that noise down, you'll find the relay..If however you don't hear a "Click" you may not have one or it is inoperative..

08-08-2006 04:45 AM
BobbyG-39 Thanks for all the help . Here's some more info:

Doc, yes I am trying to do a stock swap out on my 1939 Ford Panel truck. The Panel is a restomod, with a 350, Mustang II front, and GM steering column and trans. The "stock" or existing horn worked. It is mounted underneath the front fender, forward of the wheel. There are a few wires that come out of a hole under the fender, including the front hi beam, lo beam, and HORN. None of these have a relay as you discussed, but it is possible they are relayed back near the harness underneath the dash. I'll have to look. The car has power windows, so I hope they're using a relay since most of you guys say its important.

Last night, I hooked the existing HORN button to the + on the ooga, and used a spare wire I had laying around to go from the - on the ooga to a bolt on the frame. The ooga worked, but of course I didnt have the ground wire secured and the vibration from the ooga sound made the ground wire fall off. So I'll need to try it again today and look and see if there is some kind of relay. I am hoping if a relay is needed, they did this under the dask where I see a ton of wires and the fuse box.
08-08-2006 02:17 AM
docvette Doc here,

In answer to your question:

A Relay allows you to control high current devices with a very small amount of current safely, and (if the wires are properly gauged and fused) deliver more current to the end user device with less or no heat loss through the relay device..

A relay is a two fold device, though both sides are separate and isolated, operate in concert to activate the relay contacts.

The control coil that moves the current handling contacts, it (the coil , usually draws around an amp) and, second the contact side of the relay, which does all the high current handling from source current (battery) to the end used device ( Horn, lights, Ignition coils, ECT..)

Net result : brighter lights, louder horns, better overall performance of a coil, limited danger of harness and switchgear burnout from over current by user devices.

Back to your problem:

First, not clear on WHAT this is being used on...(type car..)

Second , when you say replace stock horn..are we to assume that the original one worked?

or are we talking new column, new wires and the like?

If it's just a stock swapout..the car's system already has a horn relay..that will be on the wire going from the horn should just be able to plug the new in where the old came out.. Ground the horn wire and hook the red to the wire going back to the relay or where the old horn was.

If it has all been changed, then wiring of a new relay is needed..just bare in mind that the button on the horn ring is GROUND for the relay, not power..else you will have smoke when you hit the horn.

As was said:

The relay coil wires hot at all times #85(to the battery, fuse at about an amp slo~blow) and the ground side #86 to the horn ring..

The contact side of the relay will be Normally open side #87 to the Battery Via a 20 Amp fuse, and the center wiper #30 to the horn itself.

87a will not be used...

08-08-2006 01:07 AM
To wire horn relay...

Using common 20 Amp driving light relay...
Terminal 85 goes to 12 v source from old horn. Existing wiring OK to use.
Terminal 86 goes to new ooga horn + using 12 ga wire.
Terminal 87 goes to horn ring to ground when horn button is pushed, existing wirink OK to use.
Terminal 30 fused to battery. Use 12 ga wire.
Ooga horn - to ground using 12 ga wire
08-07-2006 08:16 PM
BobbyG-39 what does the relay do? I assume I just run the positive "HORN" wire to the positive relay, then a positive out to the positive ooga, and another wire from the negative ooga to a grounding point ( i.e. the frame? ) Or do I need to involve the relay in the negative connection?
08-07-2006 07:48 PM
matt167 run a relay, using the existing wiring to activate the relay. ooga and Awooga horns draw a lot of current and with running them direct, they may sound like a sick cow.
08-07-2006 07:24 PM
Henry Highrise Just wire the minus side of the ooga horn to a good ground somewhere. Make sure that where ever you ground it that the rust and paint etc. is removed. Or you could run it to the negative battery post.
08-07-2006 07:19 PM
Replace existing horn w/ ooga horn?

I have a 12 volt system and a Harbour Freight ooga horn. I want to replace my stock horn with the ooga horn. I have a GM column with a LeCarra wheel. I removed the old horn, and there is only one "connection" on it, which is a wire going to it labeled "HORN". The ooga horn has both a + and a - connection. So I connected the "HORN" wire to the + on the ooga, but it does not work. Do I need to add something else to the - connection? I have seen messages with relays and flip switches, bit I really just want to disconnect one horn and install the oooga so it works with the horn button. I am a newbie to this, can you help?

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