I have a 46 Chev half ton that I am restoring. How do I isolate the horns from the body so that they only ground through the horn button. I didn't pay close attention when I was dismantling them.
Should be a rubber isolated mount. See discussion in General Truck Talk from last week for photos.
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I don’t believe that is necessary or desired on horns. The horn frame completes the circuit to ground. The idea is, the horn button grounds one side of your horn relay. When horn button is pushed it activates the horn relay putting battery voltage onto the wire tab or wire connection on horn. Inside the horn itself is a set on contacts which open and close by way of mechanical interference of the horn diaphragm. One side of the contact set is grounded to horn body. This is of course only true if the truck has a horn relay. The rubber bushings might be there for vibration.
the schematics seem to show that early horns didn't rely on a relay, therefore the rubber mount is not for electrical isolation, it must be purely mechanical isolation then?
early horns have two connections, one is battery hot from the back of the amp-meter and the other goes to the steering wheel switch for ground. horn current does not register on the battery charge/discharge indication, the horn power is tapped off on the battery side of the amp gauge.
however all my schematics are for USA model vehicles, and the Canadian vehicles i deal with have a different horn setup than the common south of the border ones people discuss on here. and my earliest trucks all have two horns and a relay and the horns have only one wire connection and MUST use the chassis ground which would not be compatible with a steering ground switch unless you use a relay (which is not on any schematic i found)
so you could be right about needing a relay, if you have a horn that only has 1 wire connection, but then that means the rubber mount must have a feature to connect the chassis ground to the horn body around the rubber vibration isolators.
we probably need a time machine to know for sure, unless someone has very good original "as built" documentation. -s
If I had a horn with two connectors the first thing I would check is if the connector going to the horn button is common to the horn frame. If yes, then you need electrical isolation of the horn body to body. The right size grommet and two washers would do it. If no, then no electrical insolation is need at the mount. I would not care for all that current at the wimpie horn button. Personally, I would wire in a relay where it can’t be seen. Do a little wiring change and no one could tell if it’s as original or not.
I am trying to debug a horn problem on my 1948 Chevy 3/4 ton truck. I press the button located in the center of my steering wheel and I do not hear anything. I checked my schematics in my Chevrolet Truck Shop Manual and I don't see the relay. I used my volt meter and I see 0V on the terminal on the left. I see 6V on the center terminal. I see 6V on the right terminal. When the button is pressed, I don't see any changes to these voltages.
I would love to see the schematic when the relay is used. I would also like to see the schematic of the relay itself.
The center terminal has a wire going straight down to my starter, where 6V comes in from the battery.
If I take a screw driver and short the left terminal, which is connected to the horns, to the center terminal, giving the horns power directly, I get a little sound from my horns... just a little horn pop. Nothing like a real horn blast.
Do these horns look original to you guys? Are these 6V? If no... can you show me a picture of what they are supposed to look like? Where can I get new ones?
