horn wiring from scratch
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Senior User
Joined: Jul 2002
Posts: 123
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From: baconton usa
horn wiring from scratch
ok here goes I have a 67 f100 I just put a 79 automatic column along with a whole other bunch of goodies when I got the truck the horn was run by a push button on the side of the column I would like to hook it up the right way I think I have an idea of how the horn works but not sure the best I can figure out is when you push the button a ground wire going to the relay triggers 12v from the battery to the horn much like the starter solenoid except triggered by a ground wire off of the steering column if I am right can somebody give me some kind of diagram showing which wire goes to which terminal on horn relay I am starting from scratch.
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
horn wiring from scratch
You're right about the horn button "grounding" the relay to activate the horn.
As for proper wiring of the relay you need to find out which terminal does what. I would assume one terminal is a common for positive on coil and contacts. One other would be the neg side of coil(which would go to horn button), the other is the opposite side of contact that would go to horn.
If you use an ohm meter go between terminals. two will have open reading....thats the contacts, the others will have some resistance....thats the coil. You will also find another variation that is open....but that is because it is the open side of contact and the coil.
One way to figure it out is put 12v across two terminals...if it clicks then that is the coil. Now one of those two is the common to the contacts also. You need to figure out this correctly or it will short badly if you dont have the positive on the right side. Without tearing it apart to see, I am not really sure of a easy way to find out. Unless someone knows here.
Larry
As for proper wiring of the relay you need to find out which terminal does what. I would assume one terminal is a common for positive on coil and contacts. One other would be the neg side of coil(which would go to horn button), the other is the opposite side of contact that would go to horn.
If you use an ohm meter go between terminals. two will have open reading....thats the contacts, the others will have some resistance....thats the coil. You will also find another variation that is open....but that is because it is the open side of contact and the coil.
One way to figure it out is put 12v across two terminals...if it clicks then that is the coil. Now one of those two is the common to the contacts also. You need to figure out this correctly or it will short badly if you dont have the positive on the right side. Without tearing it apart to see, I am not really sure of a easy way to find out. Unless someone knows here.
Larry
Elder User
Joined: Jun 2002
Posts: 851
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From: Elizabeth City, NC
horn wiring from scratch
I have a 68 with a 78 column. The difference between our year truck and the later columns is our tucks operated off of a one wire system. The later years operate off of a two wire system. Take off the horn button, this is done by rmoving the two screws on the back. Unplug the horn button. Now do some resistance measurements to find out which wires at the bottom of the column coincide with the two terminals you unplugged the horn from. When you find the two wires, ground one of them to chassis ground. Connect the other to the blue/yellow stripe wire on the original harness connector. This blue/yellow wire runs to the horn relay. Once you depress the horn switch you will be putting a ground on this wire of the horn relay. As far as the relay wiring, There are two yellow with green stripe wires. One goes to the Battery side of the starter relay and the other one goes to the horn. The third wire is your blue/yellow stripe. I am doing this off the top of my head so forgive me if I messed up the wire colors.
