Alarm to Siren


Oct 5, 2010
San Diego, CA
Does anyone know if it s possible to hook my alarm to my siren so if it gets set off the siren goes off in stead of just the horn? Its a 2000 F350 and the siren is Sho-ME 31.2515


May 26, 2010
Delaware, USA
it'll take some work with a multimeter, but it should be possible anything from the alarm system gives a constant +12v.

You'll have to splice into the data cable going from the switch box to the siren box and see how it works. I'd guess that those 4 "un-used" terminals are to manually select the siren tones, but that's only a guess. I'd try putting a very low amp +12v power to them one by one (with power to the unit) and see what happens. That's how their other undercover sirens operate.


May 22, 2010
long island new york
or you could wire it into the dome light circuit with an adjustable delay on break timer set at say one or two minutes.

might be less expensive or atleast less risk of burning out alarm system
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May 21, 2010
Unitrol 80Ks have an alarm function. I think you ground it to get the tone to come on if I remember right. Those amps are cheap.


May 21, 2010
Long Island, NY
911 said:
i have seen one hooked to a ss2000, and hideaway strobes ...... nice output !!!

LOL, why am I suddenly imagining some skel breaking into a car and triggering the alarm and start to panic thinking "oh crap, the cops are here already?"


May 22, 2010
Cant one just tap into the activation wire on the alarm? The same wire than makes the horn honk and car lights flash because then it would be powering up whatever is hooked to it?


New Member
Nov 4, 2010
United States/New Jersey
SFR1986 said:
Does anyone know if it s possible to hook my alarm to my siren so if it gets set off the siren goes off in stead of just the horn? Its a 2000 F350 and the siren is Sho-ME 31.2515

just in case you haven't yet accomplished your alarm/siren hookup, here are the details from a proffesional point of view.

2 things you have to keep in mind here. 1) if your Sho-Me is hooked up to ignition (meaning that your Sho-Me does NOT work when ignition is off) then you'll need a relay that will kick the Sho-Me on when the alarm goes off. 2) what kind of signal activates your Sho-Me, is it a + pulse or a - pulse? Your alarm wire (coming from the brain, going to the noise-maker in the hood) is most likely a 12+ wire but depending on the alarm make/model, it may have an additional - wire.

Here is the deal. First off, your Sho-Me will have to be powered up when the alarm goes off. So, if your Sho-Me is anyways on 24/7 then it's not an issue but if your Sho-Me is powered up thru ignition on then you'll need a relay to power it up when the alarm goes off. 2ndly, one the Sho-me is powered up you'll need to send it a tone activation signal from the alarm to the Sho-Me. So, if the Sho-Me uses a + signal to activate the tones then you use the alarm + wire for that function. If the Sho-Me uses a - signal to activate the siren tones then (depending on the alarm's make/model) you'll be using the alarm's - wire for that function. If the Sho-Me uses a - signal and the alarm does NOT have a - output then you'll need a relay to flip the + wire from the alarm to a - signal.

If you have a basic understanding in a vehicles electrical system and the uses/functions of a relay, then the above is the most comprehensive information you can get regarding your particular project. If you need some diagrams of how to actualy make it work and/or how to wire up relays then you can email me. Don't forget to include the make and model of your alarm system.



May 23, 2010
New York
I have my Sho-me 4 function siren hooked up to my siren.

I put a relay on the alarm small speaker wires as the trigger. I have that set up for 5 years now works like a charm.

If you don't want the loud chirp everytime you lock/unlock your car put a 5-10 second time delay relay as your trigger relay .

Its a 4 wire job a piece of cake !!!

30 - 12v +

85 - ground

86 - trigger from small 12+ wire from alarm brain going to speaker

87 - siren input

Harbor Patrol

May 22, 2010
ive been putting my alarm through my backup siren for years, and it works!!

once a guy tried breaking into my car-put a screw driver into the side of the window, shattered the window, i saw it on CCTV from the building where my car was parked over night, and the second the alarm/100w siren went off-bec you can see the headlights blinking, the guy fled like no tomorrow! had the window replaced and nothing was taken from the car


May 16, 2010
Deer Park, WA
The Omega 90 has an alarm input available. Makes for a very attractive attention getting sound that's distinctively different. Just ground the input and after a delay (intentional), it will go off. It's used for high temperatures for K-9 vehicles.

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