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Discussion Starter · #1 ·
I have recently acquired a 91 Ultra Glide. An absolute beauty! However, the horn makes a "thonk" sound when activated. I replaced it with a little over the counter car horn, to pass inspection, and it does honk, but real whiny. I purchased a new OEM horn from the dealer. Same result. I got 12 volts, at the wires, but no honk?? When I attache the new horn to my battery charger it works fine. I'm thinking it may be an amp issue, but i dont have an amp meter. Any direction or thoughts would be fantastic!!
 

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I have recently acquired a 91 Ultra Glide. An absolute beauty! However, the horn makes a "thonk" sound when activated. I replaced it with a little over the counter car horn, to pass inspection, and it does honk, but real whiny. I purchased a new OEM horn from the dealer. Same result. I got 12 volts, at the wires, but no honk?? When I attache the new horn to my battery charger it works fine. I'm thinking it may be an amp issue, but i dont have an amp meter. Any direction or thoughts would be fantastic!!
Have you checked the relay yet ???

If it's not wired through a relay, it needs to be, otherwise the current draw will burn the horn button contacts causing a low current flow problem .
 

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Discussion Starter · #4 ·
Had to order a shop manual for it. Will arrive next week. I did attempt to trace the wiring, but once it entered the fairing {a wiring nightmare} I wasnt able to find it. Wasn't sure if there was a relay or not. Would a bad relay restrict current like that?
Thanks for the reply.
 

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Had to order a shop manual for it. Will arrive next week. I did attempt to trace the wiring, but once it entered the fairing {a wiring nightmare} I wasnt able to find it. Wasn't sure if there was a relay or not. Would a bad relay restrict current like that?
Thanks for the reply.
Yes it could . :)
 

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Webco's comments are spot on. I put a set of Fiamm Highway blasters on my Electra and was very disappointed with the sound. I added the relay (as instructions say), and the sound is as should be. Your stock relay is probably bad.
 

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There is no relay for an OEM horn.

You are reading 12v at the horn connector, but you are reading that voltage while the horn is disconnected, right?

The problem is excess resistance in the circuit, due to a bad connection, a bad switch or bad ground.

It can provide 12v when connected to a voltmeter, because a voltmeter draws very little current, but when you connect the horn, the excessive resistance does not allow enough current to pass through the circuit to operate the horn.

Connect the wires to the horn, then connect the voltmeter to that circuit and push the horn button, you will see very low voltage.
 

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A good quality Heavy Duty 30AMP relay will make that horn scream ! Same for your headlight , will increase brightness 2-fold .
 

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There is no relay for an OEM horn.

You are reading 12v at the horn connector, but you are reading that voltage while the horn is disconnected, right?

The problem is excess resistance in the circuit, due to a bad connection, a bad switch or bad ground.

It can provide 12v when connected to a voltmeter, because a voltmeter draws very little current, but when you connect the horn, the excessive resistance does not allow enough current to pass through the circuit to operate the horn.

Connect the wires to the horn, then connect the voltmeter to that circuit and push the horn button, you will see very low voltage.
What he said, exactly.
Not enough current is flowing to the horn when you push the button.
 

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Try cleaning the horn ground wire connection on the engine.
 
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