Making a pulsed output for a horn

Hey Folks I have a small problem with my car alarm. I wanna add the factory horn with the alarm siern. I have a constant output from the brain to run the siern but, I need to have a pulsed output for the horn, so, it won't burn up. I've looked at the relay section on the webpage and when i use the 12 volt flasher for the pulsed output, all I get is a constant horn. The horn needs a negative input for it to operate(Ford Mustang). This is how I have it set up using two relays. 86 connected to + siern output from brain 85 connected to ground 87 connected to 12V+ 30 connected to X on flasher using another relay to change polarity, I have comming from the L on the flasher to 86, 85 and 30 are connected to ground and 87 connected to the horn which is a negative input. This did not work and gave a constant horn output so, I moved the flasher in between the 87 and horn connection on the last relay and, it still gave a constant output. Any help would be appreciated. Thanks Aaron Aaron

I don't think you need a second relay. Try this: 86 connected to + siren output from alarm module 85 connected to ground 87 connected to L on flasher 30 connected to ground X on flasher connected to horn If you can't make it work in anyway, it might be because you're using a mechanical flasher. They're designed taking a lightbulb filament's resistance into consideration, so you might have better luck using an electronic flasher. Good Luck!!

How about this? relay one: 85 Siren input, 86 opposite polarity of siren, 30 ground, 87 output to relay 2. Relay 2: 85 flashing lights from alarm, 86 opposite polarity of flashing lights, 30 input from relay 1, 87 output to horn. Give it a try, the horn will honk when the lights flash while the siren is on.Certified Security Specialist

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1. Establish the the horn has a constant 12 volt source with the key off. (I believe most Ford's do) Here is the proper way to wire by flashing the 12v side of the horn. This will work even if the 12v horn wire is ignition switched. You will need to cut horn + wire and pass through relay. Relay # 1 86 - siren 12v output from alarm 85 - ground 87a - horn 12v in(hot side) 30 - out to horn + 87 - 12v in from flasher output (12v into flasher) Relay #2 (sends constant ground to neg. of horn) 86 - siren 12v output from alarm 85 - ground 87 - ground 30 - connect to negative of horn Done this many times. Most VW horns require this.