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Horn electrical hook up help please

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ichthos

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The stock horn on my Bugeye was just was not loud enough to get the attention I need in an emergency, so I bought one of the compact air horns from Moss. I do not understand the directions that came with it. The part that is confusing me is what I think is the relay. There is a + and - terminal on the new horn itself. I have the original two wires coming from the steering wheel. I have to hook up the original horn wires to the relay, and then run two lines to the horn itself. How do I know which terminal on the relay to hook into? Any help would greatly be appreciated.
Kevin
 

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It would be best if you PM me.
Have you converted to neg. ground? I think you used the original harness.
OK, there are two wires going to your horn.
One wire should be brown/green. That wire is from the fuse box. If is HOT all the time. The other wire should be brown/black, and that wire goes to the horn switch in the steering wheel.
The relay is composed of four contacts: two for the coil, and two for the contacts. When 12V is applied to one side of the coil and the other side is grounded, the contacts close.

Please verify all your wires before you proceed.
Disconnect the battery.
Connect the brown/green wire to one of the coil contacts, doesn't matter which one. Connect the other coil contact to the brown/black wire. So far, this allows the horn relay to activate if the horn button is pushed (assuming the battery is reconnected)

Keep the battery disconnected.
Connect one side of the contacts of the relay to the brown/green wire also. Connect the other side of the contacts to the horn (was connected to brown/green). Run a wire to connect the other wire from the horn to ground. When you reconnect the battery, the horn should blow when you press the horn button.
cheers,
Scott
 
Kevin, there's a schematic here - it's for headlights but it is the same. Basically, the relay should have numbers by the plugs. The old horn wires will cross #85 and #86. The power needs to go across 30 and #87. Direction doesn't matter as they are both switching circuits.

https://www.advanceautowire.com/
 
How did you know what the numbers were on the relay without me telling you, JP? Are the numbers standard on a relay? Scott, I will check out the information you asked me to check and PM you. I do have negative ground. I don't have the push button or horn push contact in yet (the push contact is too tight. I think I have too much paint build up or something.) Will it hurt the horn if I just hook it up to the battery? I just wanted to see what is sounds like.
Kevin
 
If you want to hear what it sounds like, hook up one wire each of the horn. to opposite sides of the battery. Wear ear plugs.
JP has that superman vision that allows him to see small things thousands of miles away. May the force be with you JP!
Cheers,
Scott
 
I tested the horn. Wish I would have taken your advice on the ear plugs, Scott. Ouch. I am looking over the diagrams included with my horn, and it is starting to make more sense. I checked, and the brown/green wire is hot, so that goes to terminal 30. Terminal 87 then goes to the positive side of the horn. If I understand you correctly JP, the brown/black wire can go to 85 or 86 and doesn't make a difference, correct? Then which ever terminal I don't use goes to the negative side of the horn, correct?
Kevin
 
While JP may have super powers, yes most all relays have the same numbers.....

1. Connect the brown/green wire to 86 on the relay.
2. Connect the brown/black wire to 85 on the relay.
3. Also connect 30 on the relay to brown/green.
4. Connect 87 on the relay to the + side of the horn if there is one.
5. Connect the - side of the horn if there is one, or the other wire to ground.

BTW. Sometimes the horn switch does not "find" a ground path through the metal steering wheel to ground. I had that problem on my BE and added a wire from the rack to ground.

Good luck.
 
I hooked up the brown/green wire to 30. I then hooked up 87 to the positive side of the horn. I hooked up the brown/black wire to 85. I then hooked up 86 to the negative side of the horn. Pushed the horn button and ...nothing. Grounding has been a problem because I have painted things so well. I am burned out. I guess I will go at it again tomorrow. Thanks for your help.

By the way, how would I know if the horn button is working?

Kevin
 
The horns are wired wrong. Wiring requires that all connections be made correctly, and I'm sure you were tired.
With the way you have wired it,
Unhook 86 from the negative side of the horn and connect it along with the 30 from the relay to the brown/green wire. Now you should have two wires connected to brown/green (relay 30 and 86).
Now connect the neg. side of the horn to chassis ground.... like run it to a bolt which goes into the frame.
To test the horn, ground the wire that goes up to the steering wheel.
If you would like a diagram of all of this, PM me.
Scott
 
I will need to wait for my local auto store to open up so I can get some electrical connectors. I will hook it up and let you know how it goes. Hopefully Thanks for sending the diagram.
 
smaceng said:
JP has that superman vision that allows him to see small things thousands of miles away. May the force be with you JP!
Cheers,
Scott
Click to expand...

Yes he does, all due to that radioactive spider bite. However, now that you know it, I need you to help with the story the government told me to tell, namely that Bosch standardized the numbers. That way I don't have to move to another city and change my identity - AGAIN
 
I have one of these horns. let me try to make it very easy for you...

85 and 86 are the coil points of the relay. energize these with your existing horn circuit. ..go no further until you try you horn button and hear the relay click. That's all you want on that part. click on click off...

next run a new wire, #12 or #10 from your battery to point 30, but be sure to put a fuse in the line, preferably where you can easily reach it. I put so that the inline fuse holder wire goes right to the relay. Now run a wire from point 87 to your horn. if positive ground hit the negative of the horn if negative ground hit the positive on the horn. now take one more wire from the remaining terminal of the horn and put it under the bolt you used to mount the horn to the body. This will ground it.

BEEP BEEP... you're done.

By doing it this way, you limit the current that flows through the original switch (the horn push) to the amount needed to pull in the coil of the relay, somewhere in the milli-amp range, so the switch should last as long as the car. All the current to power the horn, somewhere near 18 amps !!!! comes directly from the battery.

I found out that original horns draw about 20 amps of inrush current, and 4 or 5 steady state energized. Since dual horns were an option, this means that the most likely rating of the horn push is only about 10 amps. Sure it will blow the horn using one of the wires from the horn push, and jumpering the relay, but for how long?

Hey, I like your mounting bracket much better than mine. I'll see you at the AUTOJUMBLE on the last sunday of April at Montgomery Park, OK?
 
I have in a 20 amp fuse that came in the fuse holder that came with the the horn. I got mine from Griot's Garage. ...

Please excuse me. I had you confused in my mind with lessingturbo, who lives in Portland. When I saw that you are from Washington, I realized the difference. My bad...but..

The AutoJumble is the All British Swap Meet. It is held every year on the last Sunday of April, hosted by the Oregon MG "T" club. They have it at Montgomery Park, which is the old Montgomery Ward Building. It's in the parking structure, so it goes on rain or shine, and is the first "event" of the year. Every one in the LBC community comes out for the first chance to see what others have been doing all summer, and it's a chance to pick up a that part one has been looking for.
 
I should probably start antother thread but...Is it open to anyone to sell? Are there other cars besides mg's? What are the hours and cost? I have a ways to go before I trust my Bugeye.
Kefin
 
as far as I know there is no cost to anyone to either attend, or sell, and yes, open to anyone and everyone all makes of British cars. I usually get there around 09:00. Some vendors are in full swing, and others have yet to arrive. ..

I just checked..(https://www.clubtmg.org/autoJumble.html) and find it's $10 for a spot to sell, and has been moved to the first Sunday of MAY..full info at the link.
 
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