OK, crazy question I know... but... base Custom model F250 highboy 1975.... where in the world is my horn?

So I can't find the dang thing. And the only bare wiring I see towards the front that mght have been where it was is a single yellow and green wire near the voltage regulator and the battery on the passenger side. Is that it? Does it ground through chassis?

 

As far as I know you should have two horns mounted towards the top of the core support on either side of the radiator... I'm sure someone will be along soon with diagrams/pictures/ more detail explanations

 

Yeah, I saw that in a schematic somewhere (Can't find it now of course) but they aren't there and there is only wiring (the Y/G wire) on the passenger side. Nothing on the drivers side.

I can't figure out why they would have removed it. But I am trying to find a short in that circuit and want this fixed before I go chasing other issues.

 

One horn was standard, two horns was an option. When you got two horns they were different, one hi pitch, the other low pitch.
The yellow/ green trace wire is the correct one for the horns and the location for one horn was on the radiator core support on the passenger side, between the radiator and battery. With dual horns the second was placed in the same location on the driver's side.

 

Perfect! That's exactly what I needed to know. Also, by the look of your truck... mind just photographing everything possible and posting it all for the future? ha!

Shane

 

Actually I'm kinda doing just that. This is a link to my build thread.
https://www.ford-trucks.com/forums/8...with-pics.html
It's now year 8 of a "planned" five year project . No, it's nowhere near done yet!

 

Normally only 1 horn on the passenger side of the core support, like in the pic. 2 only if you have the duel horn option and the split off wire.

 

Did you try honking it? It sounds like it's missing not hiding.

 

And if your truck is the type without a horn relay, you might consider adding one while you're mucking about with the horn circuit. It takes the load off of the horn button contacts and gets more juice to the hungry horns.
Of course, if yours came with one already, you're good to go!

Paul

 

The OP's truck is a '75 so it will have a relay.
It was the '78 and '79 models without factory cruise control that didn't have a relay. If you have a 78-79 model with cruise then you also have a relay.

 

got it. Thanks.
And yep, mine is a '79 without cruise.

Paul

 

When did Ford first start using relays for the horn anyway? Was it during this time, or way before that?

Paul

 

Waaay before.

One example: 1948/55 6V: FAA-13853-A .. Horn Relay.

 

Hey guys, thanks for the help. I found the spot to hang the horn, found the wire. found the relay. checked the voltage... everything is good.... but plugged in a AZ horn and no love. I can hear the relay pop, watch the voltage at the horn, but no sound.

It may be that I have to take some sandpaper to the rust in the mounting location to get a good ground... not sure.

 

You can attach a ground to the horn directly to see if the horn honks. If not, then the horn has the issue. If it does, then you just need a better ground.
At least if it's a factory horn. Most aftermarket horns use a separate ground connection. But it's usually obvious, so guessing yours is a stock one.

Paul