So I was hooking up my garage opener to a switch and power it through the cigarette lighter, which is working great by the way. While I was at it, I thought I might have some fun with the alarm siren.

This is what I was trying to do. Traced the power/ground line from the alarm siren to the security module (or whatever you call it). I then tap the power line to a momentary switch which is also tapped to the cigarette lighter power. So the idea is when I press the switch, voltage would go through the switch and powers the alarm siren. But that doesn't work.

I know it's kind of bad, but I have multiple things connected to the cigarette lighter (V1 radar detector, garage opener, and alarm siren). But I figure the only thing that is really on is the V1 and others are connected to two separate momentary switches so no current are not drawn unless the switch is pressed. Plus I have inline fuse holders for all three units.

Now one thing I noticed is that when I have power off (no key). If I press the switch for the alarm siren, the radar detector would come on, which tells me that the power line to the alarm siren is actually always powered. So what is the deal? What, am I suppose to tap the ground instead? So when press I can complete the circuit and the siren would come on when I press the switch? Let me know guys. Thanks!

 

So just as i suspected. I tapped the ground wire instead and tapped the other end of the switch to the ground. and BAM! My siren will come on when I press the momentary switch.