siren addition

Can I add a siren to an alarm without an output? I don't need it to be able to go off, I just want a chirp for when I lock and unlock. My doorlock system on the car is a single wire negative. I can hook up the + to a +12 source. Then I was thinking that maybe I could tap into the door lock/unlock wires to provide me with the (-) side for the siren. So when the module sends the (-) signal for the door locks it would also send the (-) to the siren. This would in theory create a chirp. Would this work? How about tapping into the horn? It is a valient keyless entry system and a 99 grand am.Dyer

Yes, you can use the doorlock outputs to trigger a relay to chirp the siren. I would suggest, first to diode isolate the doorlock output wires from 2 wires, split into 4. 2 go to the doorlock wires, 2 go to a relay for the siren. I would ground the siren at it's mounting point ans send a 12v+ pulse to it. 86 = (-) from lock/unlock 85 = 12v+ (see 87) 87a = not used 87 = 12v+ 5amp fused with 85 30 = 12v+ to the siren Viper Equipped

do I need 2 relays? One for lock and one for unlock?Dyer