# Installing a second Horn



## ukrkoz (Dec 31, 2010)

hook up horn wire to horn terminal on relay.
horn normally grounds by being screwed or bolted to a metal frame.
connect the rest of relay wires as marked. switch to switch, power to power, ground to ground.
you flip the switch, and relay sends power to the horn. relays it. just make sure you have good horn ground.


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## zoiberg137 (Jan 18, 2012)

Ok so by doing it that way I will only have ONE wire going from my switch to the relay, even though the switch has two terminals on it...

I admit that I don't know much about electricity but I always thought you had to have a loop of some sort. Just for curiosity, could you explain how having only one wire going from the switch to the relay can work??

Thanks!


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## Evstarr (Nov 15, 2011)

The metal parts of the car make up the negative 'wire' in most cases.


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## 47_47 (Sep 11, 2007)

This is for a Bosch relay. 
A power wire goes to one side of the switch. The other wire of the switch goes to relay terminal 85. terminal 86 gets a wire to ground. 30 gets fused battery power. 87 goes to horn.
When you turn the switch on, a small current flows through the switch to the relay, completes the relay ckt, closes the contacts, and allows a larger current to flow from pin 30 to your load.


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