The Stovebolt Site Forums The Shop Area The Electrical Bay Testing horn

I have an original 6v horn. I try going directly across the 6v battery. It sparks when I make the connection, the horn make a little sound and the wire starts to warm up, but it does not sound off like a horn. Do I have to wire it through a relay to get it to work or is it bad?

It is bad.

IF (big if) you can open it up without destroying it, try cleaning the contacts with a very fine sand paper.

Not the answer I was hoping for but the answer I expected. I picked it up this past weekend at a swamp meet for $10. I will drill out the rivets and give it a try. I have nothing to lose at this point but a little time doing something I enjoy anyway.

I recently had one that did the same thing and the issue was that the contacts needed adjusting so they would open and close properly.

I will see if I can find the pictures from when it was apart. The contacts also needed cleaning, but the adjustment was the real fix.

Agree with adjusting if there is a screw on the outside. Contacts are pretty big and healthy inside. Before taking apart I would shock it several times with bursts of 12V. This is provided you are 100% sure you have it wired correctly while load shocking. I would also "knock" it around a bit, like vibration mode, with a dead blow hammer. Usually no wiring inside, just "stuck" contacts. Not fused together, just corroded. Taking it apart won't hurt it unless you are a relative of Little Lulu.

Does the polarity have to be correct?

If it has two terminals, check to see if you can detect that one is not insulated. Check for markings. Maybe used before horn relays, before a one terminal/case bolt ground. Do a continuity check on each terminal to the case. Take off paint to get ground test spot.

You say it's an "original". You have a 1954 truck. So if you mean original 1954 horn, it has ONE hot terminal supplied by a horn relay and the case is the ground to chassis.
This wiring method started in 52/53 in trucks and earlier in cars (back to 1942). Some early GM vehicles with dual horns had relays.

I assume it has two terminals or you wouldn't be asking about polarity. You don't have an original 54 horn if it has two terminals.

I don't think it matters. My horn has a screw holding on the rear cover that when removed allows adjustment of the contacts. But it didn't need any adjustment, just a little cleaning and painting.

I don't know what year the horn is or from what vehicle. It appears earlier than my 54. Probably 40's. It has one terminal. There are no markings of any kind on it. I ask about the polarity because I know some of the earlier systems were positive ground and because I don't know what year or manufacture the horn is I wasn't sure if it possibly came from a vehicle that was a positive ground system.

I don't think the horn will care about polarity.

The seller of mine said they were off a Chevy car, Fleetline, 6 volt. The stamping is 643 low tone and 644 high tone, with single terminal. darn near sounds like a Semi on 12 volt system.

A 6v horn sounds EXTRA loud when powered by 12v.

Your horn is probably a 6v horn.

I have cleaned up four successfully so far, but avoid the temptation to take them apart too far. I've made that mistake on one. They are pretty simple but easy to break/shear screws/lose tiny parts/get things out of order. Opening up at least the body might be necessary just to clean them up. And keep in mind the pot metal these are made from does not flex.

Up where I am, spiders of all darn things go inside them and make nests, creating a lot of corrosion. Has been possible to rescue the above four, but until I opened them up there was no way to tell what was hiding inside. Just looking into the horn flare (?) they "looked fine" but didn't work. A good cleaning and some patience, they worked - play with that adjustment screw for sure. And yes, as noted above, 6V horn works on 12V just loud as blazes.

I think I still have one more on the "queue" to look at one of these days.

Do you think it is safe to poor some sort of solution into the horn to help wash out any debris and corrosion without damaging the horn? What would be the suggested solution. Something like CLR? I didn't know if trying this before taken the horn apart might be an option.

My horns didn't work when I first got my '48.There were 2 flat pieces of Bakelite in the horns. I guess, when they vibrate, they make the noise. They were stuck together so I slipped a razor blade between them and they worked.

When I went to 12-volts, I wired them in series (with proper insulation here and there) although that might have been overkill.

I just went back to the horn to evaluate what is involved in taking it apart. Before doing anything, I went ahead and ran the adjusting screw in and out a couple times. It is now screaming. Problem solved.

Perfect! Glad to hear it!

But , you haven’t actually heard it.

I just pulled 2 very old horns out of my trash bin and soaked the attachment points with Kroil.
Thanks for the inspiration.

Yes, it now sounds off like a semi.

I thought I had my horn issue resolved. I have a couple last scenarios/questions for the electricians in the know. I tested my horn with a 12v battery, and it sounds great. I started to install it in my 6v system and only get a click and little hum from the horn. Based on the design I assumed the horn was old enough it had to be a 6v horn. See the picture. There are no markings anywhere on the horn.

Does it need to be wired through the horn relay before it will work or is it in fact a 12v horn and that is why it won't sound off with 6 volts?

It's almost certainly a 12v horn.