I bought some air horns to hook up with my stock horn and my alarm. I need to know which wire should I tap into for the stock horns? and I want to know the diagram for the relay. How can I make it so that I can use the air horn to blow the horn and have it hooked up to the alarm (+ output from alarm).
Our stock horns are wired so both wires are normally hot. One of the wires goes to ground when you push the horn. To properly wire up most aftermarket horns you need a relay. Wire the two wires that went to the stock horns to the coil wires on a relay. On a standard automotive relay the coil contacts are 85 and 86. Then get a wire from the battery and install an inline fuse. THen run that wire to contact 30 on the relay. Relay contact 87 then goes to the positive connection on the horn. THe negative horn connection needs to go to a ground. I installed a wire that went to the body of the vehicle for my ground. If your alarm used to make the horns go off then it still will.
If you need a diagram of the relay I can e-mail one to you.