6 to 12 volt horn

[pbc]

I need some help from someone who has gone from 6 to 12 volt and changed polarity to neg. I can get my horns to work but not off the three terminal relay.I have insulated the horns that may be a problem.
s terminal to horn button
h terminal horns
b terminal to pos on battery
this is a 41 ford with trumpet horns
not sure what I am doing wrong. Before I insulated the horns I was having the same problem.Because I changed polarity my wires that use to be live are now negative any help would be great thanks paul

[40cpe]

With one wire going to the horn, the only way to complete the circuit is to have the horn body connected to the car chassis. You might have other problems, but without the horn grounded it can't work. Are you sure the relay is working? Put a test light or volt meter on the connector at the horn. Does it show voltage when the horn button is mashed? Test for voltage at the "B" Terminal of the relay. It should be hot all the time.

[1948F-1Pickup]

Had to put a second horn in on my truck when I went to 12v.
Wired them in series.

[pbc]

Thank for the response I will check for voltage at b terminal wont be till weekend. Yes I did check horn button to s terminal and it works with a voltmeter. Correction I went from battery to button and it worked

[Drbrown]

I gather you do have two horns so I also think you have a grounding problem. The horns must be grounded to the car body. No big deal but did you change the relay to a 12 volt (i.e. a 1956 Ford). Regarding voltage, some don't worry about 6v vs. 12v if there's just incidental usage. Its continuous and/or long-term usage that could cause damage.

Also, if you're using two horns, wiring them in series creates some conflicting electronic problems as the vibrators in each tend to fight each other, usually to the detriment to the second horn in-line.

[Graeme / New Zealand]

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I had problems getting my trumpet horns to work properly. Sometimes it sounded like one was working other times got the deep sound of two. I had to take them off for some reason. When I mounted them originally I mounted them with fibre washers between the horn bracket and the body. When i remounted the horns I removed those and since then I have had the a consistant deep hi/lo horn tone. Those fibre washers were the problem...poor earth.

GB

[pbc]

yes duel trumpets I have been working on this car off and on for the last few years.As I have been thinking I had these horns off and painted them.I forgot I did that. I also am leaning towards a ground.I do have the 6 volt relay I was told it still may work? This week end I will try it out instead of taking these off again I will just run a good ground wire to chassis.

[Bill S]

I agree with DRBrown.

[Flat Ernie]

It should have been 'plug and play' - there really is no difference - neither the horns nor the relay care about polarity.

The 6V horn relays have heavier internal contacts and are better suited for the higher current draw when running early horns on 12V. My favorite horns were a pair of '51 F1 Trumpets on 12V - angry sounding!

[RalphG]

Yes, when I tested my 52 Merc horns (off the car) on 12 volts , they worked, and loud! On 6 volts I could not get more than a click out of one horn. A few blasts on 12 volts seemed to clear it up and now I'm back to working them both on 6 volts. Yes, grounding is essential but I don't think it matters if positive or negative ground.