The Stovebolt Site Forums The Shop Area The Electrical Bay Horn Button

Just hooked up the horn for the first time and hit the horn button and got one beep out of it. Then it wouldn't work any more. Took stearing wheel apart and checked everything out and found that the spring in contact button had melted. The horn is original and it is just temporary wiring (14 guage)as the original wiring harness is out of the truck.I am going to change over to 12 volt system and I am using a 12 volt battery. Do I need to put a voltage reducer in the feed line to cut it back to 6 volts? Any help will be greatly appretiated. The truck is a 51 chevy and I wired the horn per the wiring diagram in the service manual.

Eric,

The horn should work alright on 12 volts for short toots. Laying on the horn for 2 minutes might give it a coronary.

Your post indicated that the spring 'melted'.

I am not looking at a diagram, but I think your rig should have a actual horn relay in the engine compartment, and the horn wire up the column should be the GROUND for the coil in the horn relay.

This ground would not be expected to pass much current, only what was required to pull the relay in.

Melting the spring in your contact button makes me think it passed full current to toot the horn.

Could this have been the case? Take another look at the wiring diagram and see if you switched something you shouldn't have. Good luck.

Stuart

Yea, what he said.

Eric,

If you used a temporary 12 volt battery with the original 6 volt horn relay, you might have done some damage to the relay...just a thought!


Stuart

It doesn't show a relay in the wiring diagram in service manual. I don't know if there was one on the truck because the previous owner had a fire under the hood and wiring harness was cut off at fire wall.All that was left were mounting holes for voltage regulator and 2 small holes just below it. Every thing else was gone.

Eric,


The plot thickens. I looked online at a wiring diagram for a '51 CAR..no truck diagram was available (?). The schematic for the car showed a horn relay, so I would assume a truck would have one too.

The bottom line is that the horn circuit into the column/wheel area isn't made to pass the current required to sound the horn....only the power required to close a little horn relay.

Look at your service manual again. If it does show the relay, wire it accordingly.

It sounds like this might be the tip of the iceberg in the wiring department..a fire!

Stuart

Elm:

Most modern horn buttons (the column mount kind) are only rated for 5A. I have my horn wired straight through, and I cooked the button. I was unable to find a 6v relay here in town, and I refuse to pay $30 for one online.

My guess is that the horn button on your steering wheel is of a similar rating, judging by the spring cookage.

I solved the problem by installing a 60A starter button in the circuit. Horn works like a dream.

A 12v horn relay is readily available at any FLAPS and they cost between $10-$20 depending upon make and specs. I'd install one on a 12v system in a heartbeat. They aren't that difficult to install, either.

Thanks for the help guys. That was my thought too, about putting a relay in the system. The old 6 volt horn sounds pretty good on 12 volts. Again thanks for the help. Will try the relay the next time I get to work on the old truck. I will let you know what happens.

The AD trucks didn't have a horn relay (from the factory) until 1953. If your horn has two posts on it, that horn does not need a relay. If one post, it needs a relay.