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Just disconnect the stock horns at the horns and use the disconnected wire(s) to your new after market horn(s).
If the new after market horn has a ground wire just ground it to the mounting screw..
Take the 85 wire and run it to your horn switch. Are you using the horn switch in the column? If so just hook up wire 85 to it. If using a push button switch, wire 85 goes to one side of switch and the other side of switch goes to ground, leave all the others as wired above. when you ground the horn switch wire it will close relay applying power to the horns.
Take the 85 wire and run it to your horn switch. Are you using the horn switch in the column? If so just hook up wire 85 to it. If using a push button switch, wire 85 goes to one side of switch and the other side of switch goes to ground, leave all the others as wired above. when you ground the horn switch wire it will close relay applying power to the horns.
Yes, stock column and switch. So constant power to 30 and 86, 85 to switch, 87a to horn. Leave 87 bare?
Thx
That is almost correct. See subford's post below. You have a single pole double throw relay (SPDT) so the extra terminal is not used
Connect 86 and 30 to +12v
Connect 85 to the horn switch
Connect 87 to the horn (NO contact)
Leave 87a unconnected (NC contact)
When the horn switch closes the circuit for the coil will energize the coil and that in turn will close the contact 87 and send 12v to the horn.
Last edited by PhilD13; Aug 9, 2018 at 01:11 PM.
Reason: correct the incorrect pinout descriptions
You are correct. I should have looked it up. I swapped the two 87 and 87a. If horn is connected to 87a the horn will blow all the time except when the horn button is pushed. Good drawing BTW.
The reason it's hooked to 87a in that other diagram is that it's either a typo (doubt it though) or because it's a slightly altered circuit function in that application.
For a simple standard relay connection, as you found out 87a is "normally closed" and 87 is "normally open" and there are certain circuit layouts where this would be utilized.
Some similar looking relays simply have two separate 87's though, for powering up two separate items such as two lights (or two horns as long as they don't use more current than the relay is rated for) when you don't want to splice them both to a single terminal.
It's funny about relays. I figured they were pretty simple remote switches, and made this type work for my old pre-relay horns (like you're doing) and pre-relay headlights (on my older cars and trucks) and other stuff too. But when you really start to dig into them, it's shocking how many different ways there are to connect them in series, parallel, or independently, to make stuff work the way you want.
Look up some of the diagrams and they make that first one posted by GoldCo look positively basic!
Glad you got it working for you. On my rigs I've always used just the basic setup. That's where 30 is to the battery, 85 is to ground, 86 is to the horn button (12v in this case) and 87 is to the horn.
Mounting the relay near the horn itself made it all very easy. Simply make up the new 30, 85 and 87 wires, unplug the original horn wire, connect it to 86 and done.
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