When connecting the relay it is worth noting the 12v supply to the horn relay via a inline fuse must also loop to one coil connection on the relay , ground wire connected to the other coil connection on relay then passes to the horn button via the column or aftermarket pushbutton. There other ways but this is the simplest form.
If the circuit is fused at 30amps keep all wiring the same size as the fuse will allow fault current upto the fuse size to pass thru the system, insulation on any smaller size cable could melt if there is a fault in the system. Insulation melting causes smoke. You do not need smoke signals
Terminal 86 12volts from supply source loop to terminal 30
Terminal 85 ground via horn button or push button
Terminal 30 12 volts from supply source
Terminal 87 12 volts to horn
