
Horn relay.
The original 65 Mustang harness was designed to send two 14 ga. wires up the column to the horn button switch. One wire with 12 volts and one returning from the switch to the horn.
Since I had installed a Flaming River steering column and a basic Grant steering wheel, I needed to wire in a relay to get the single wire horn button working. The concept is pretty simple. The horn switch turns the relay on with little current and the relay sends a higher current to the horns.

I connected this wire to pin 87 of the relay. Lastly, I connected the black wire from the horn switch to pin 85 of the relay. When the horn is pressed, this wire will be grounded and turn the relay on which sends power to the horns.
Something to watch out for is that the relay may have an internal diode so connect the hot to pin 86. If you dont have a diode, its a good idea to add one to eliminate flyback voltage spike.
In the above diagram, the horn is always on except when you press the horn button.
ReplyDelete